Semiconductor device

The present invention relates to a semiconductor device and a method for manufacturing the semiconductor device.

In the present specification, a semiconductor device is a device that can function by utilizing semiconductor characteristics. In general, electro-optic devices, semiconductor circuits and electronic devices are all semiconductor devices.

A transistor (thin film transistor) using a semiconductor thin film formed on a substrate having an insulating surface. The technology that composes (also called TFT) is drawing attention. The transistor is an integrated circuit ( It is widely applied to electronic devices such as ICs) and image display devices (display devices). Tran Silicon-based semiconductor materials are widely known as semiconductor thin films that can be applied to Jista. Oxide semiconductors are attracting attention as other materials.

For example, as the active layer of a transistor, the electron carrier concentration is 10.¹⁸/cm³Is less than Amorphous oxides containing indium (In), gallium (Ga), and zinc (Zn) were used. Transistors are disclosed (see Patent Document 1).

<p><patcit num="1"><text>Japanese Unexamined Patent Publication No. 2006-165528</text></patcit></p>

<p>However, oxide semiconductors have a stoichiometric composition due to excess or deficiency of oxygen in the thin film forming process. When hydrogen or water that forms an electron donor is mixed in, its electrical conductivity Will change. Such a phenomenon causes electricity for transistors using oxide semiconductors. It becomes a factor that fluctuates the characteristics.</p><p>In view of these problems, stable electrical characteristics are imparted to semiconductor devices using oxide semiconductors. , One of the purposes is to improve reliability.</p><p>Another purpose is to prevent the generation of parasitic channels on the back channel side of the oxide semiconductor film. Let's be one.</p>

<p>Since it suppresses fluctuations in the electrical characteristics of transistors that use oxide semiconductor films, it becomes a fluctuation factor. Oxide semiconductor film with impurities such as hydrogen, water, hydroxyl groups or hydrides (also called hydrides) Oxide semiconductors that are more intentionally eliminated and simultaneously reduced by the impurity elimination process By supplying oxygen, which is the main component material of the oxide semiconductor film, the oxide semiconductor film is highly purified. And electrically become i-type (intrinsic).</p><p>An i-type (intrinsic) oxide semiconductor is an acid that removes hydrogen, which is an n-type impurity, from the oxide semiconductor. I-type (i-type) by purifying as much as possible so as not to contain impurities other than the main component of the compound semiconductor. It is an oxide semiconductor of (intrinsic) or an oxide semiconductor of type i (intrinsic) as close as possible. .. That is, instead of adding impurities to form i-type, impurities such as hydrogen and water were removed as much as possible. It is characterized by being highly purified i-type (intrinsic semiconductor) or close to it. To. By doing so, the Fermi level (Ef) is at the same level as the true Fermi level (Ei). Can even be.</p><p>In a transistor containing an oxide semiconductor film, it comes into contact with the oxide semiconductor film to provide an antistatic function. The oxide layer to have is formed and heat-treated.</p><p>The oxide layer having an antistatic function is an oxide semiconductor film, preferably a highly purified oxide half. It is preferable to provide it on the back channel side (opposite side of the gate insulating film) of the conductor film. Also, the obi The oxide layer having an antistatic function preferably has a smaller dielectric constant than that of an oxide semiconductor. Example For example, it is preferable to use an oxide layer having a dielectric constant of 8 or more and 20 or less.</p><p>The oxide layer is thicker than the thickness of the oxide semiconductor film. For example, of oxide semiconductor film The oxide layer has a film thickness of more than 10 nm and oxidation with a film thickness of 3 nm or more and 30 nm or less. It is preferable that the film thickness is equal to or larger than that of the semiconductor film.</p><p>A metal oxide can be used as the oxide layer. As a metal oxide, for example, an acid Use gallium oxide or gallium oxide with 0.01-5 atomic% of indium or zinc added Can be</p><p>Depending on the heating process, the oxide semiconductor film can be made of hydrogen, water, hydroxyl groups or hydrides (with hydrogen compounds). Impurities such as) are intentionally removed from the oxide semiconductor film to improve the purity of the oxide semiconductor film. It is preferable to do so. By heat treatment, hydrogen or hydroxyl group, which is an impurity, is converted into water. It can be easily detached.</p><p>In addition, since the heat treatment is performed in a state where the metal oxide film containing oxygen and the oxide semiconductor film are in contact with each other, it is not possible. One of the main components of oxide semiconductors, which is reduced at the same time by the process of removing pure substances Oxygen can be supplied from a metal oxide film containing oxygen to an oxide semiconductor film. Yo As a result, the oxide semiconductor film becomes more pure and electrically type i (intrinsic).</p><p>In addition, impurities such as water and hydrogen will not be remixed into the oxide semiconductor film after the heat treatment. In addition, a protective insulating layer is added on the metal oxide film to block these from entering from the outside. It may be formed.</p><p>Transistors with a highly purified oxide semiconductor film have a threshold voltage, on-current, etc. There is almost no temperature dependence in the electrical characteristics. In addition, the transistor characteristics due to photodegradation There is little fluctuation.</p><p>In this way, a transition having a highly purified and electrically i-type (intrinsic) oxide semiconductor film. Stars are electrically stable because their electrical characteristic fluctuations are suppressed. Therefore, stable electrical It is possible to provide a highly reliable semiconductor device using an oxide semiconductor having characteristics.</p><p>The temperature of the heat treatment is 250 ° C or more and 650 ° C or less, or 450 ° C or more and 600 ° C or less, and Is less than the distortion point of the substrate. Heat treatment is nitrogen, oxygen, ultra-dry air (water content is 20p) Air below pm, preferably below 1 ppm, preferably below 10 ppb), or rare gas It should be done in an atmosphere (argon, helium, etc.).</p><p>One form of the configuration of the invention disclosed herein is a gate electrode and a gate insulating covering the gate electrode. A film, an oxide semiconductor film in a region overlapping the gate electrode on the gate insulating film, and an oxide semiconductor film. The source electrode and drain electrode in contact with the oxide semiconductor film, and the source electrode and drain electrode in contact with the oxide semiconductor film. It is a semiconductor device having a metal oxide film covering a rain electrode.</p><p>In the above configuration, it is preferable to use a gallium oxide film as the metal oxide film. Oxidized gully The um film can be obtained by a sputtering method, a CVD method, a vapor deposition method or the like. Gallium oxide film Has a bandgap of approximately 4.9 eV, depending on the composition ratio of oxygen and gallium. It has translucency in the visual light range.</p><p>In this specification, gallium oxide may be referred to as GaOx (x&gt; 0). For example, Ga If Ox has a crystal structure, Ga with x = 1.5₂O₃It has been known.</p><p>In the above configuration, the metal oxide film contained 0.01-5 atomic% of indium or zinc. It is preferably composed of a gallium oxide film. Also, the band gap of the metal oxide film and the acid The difference from the band gap of the compound semiconductor film is preferably less than 3.0 eV.</p><p>Further, the oxide semiconductor film is preferably composed of indium and gallium. ..</p><p>Further, in the above configuration, the work function of the source electrode and the drain electrode is 3.9 eV or more. It is preferable that it is composed of the conductive material of. Conductive materials with a work function of 3.9 eV or higher , Tungsten nitride or titanium nitride is preferred.</p><p>Further, in one embodiment of the present invention, a gate electrode is formed on a substrate and gate insulation is provided to cover the gate electrode. A film is formed, and an oxide semiconductor film is formed in a region that overlaps with the gate electrode via the gate insulating film. , A source electrode and a drain electrode are formed on the oxide semiconductor film, and the oxide semiconductor film and the source are formed. A method for manufacturing a semiconductor device in which a metal oxide film covering an electrode and a drain electrode is formed and heat-treated. Is.</p><p>In the above configuration, it is preferable to form a film containing gallium oxide as the metal oxide film. I. In addition, as a metal oxide film, an oxide containing 0.01 to 5 atomic% of indium or zinc. It is preferable to form a lithium film. The heat treatment temperature should be 450 ° C to 600 ° C. Is preferable.</p>

<p>In one embodiment of the present invention, a metal oxide film is formed in contact with the oxide semiconductor film and heat-treated. By this heat treatment, impurities such as hydrogen, water, hydroxyl groups or hydrides are removed from the oxide semiconductor film. It can be more intentionally eliminated to purify the oxide semiconductor film. Highly purified and electrical Transistors with an i-type (intrinsic) oxide semiconductor film suppress fluctuations in electrical characteristics. And is electrically stable.</p><p>Therefore, one embodiment of the present invention can produce a transistor having stable electrical characteristics. Wear.</p><p>Further, one embodiment of the present invention is a semiconductor device having a transistor having good electrical characteristics and high reliability. A stand can be made.</p>

<figref num="1">The figure explaining one form of the semiconductor device and the manufacturing method of the semiconductor device.</figref><figref num="2">The figure explaining one form of the semiconductor device.</figref><figref num="3">The figure explaining one form of the semiconductor device.</figref><figref num="4">The figure explaining one form of the semiconductor device.</figref><figref num="5">The figure explaining one form of the semiconductor device.</figref><figref num="6">The figure explaining one form of the semiconductor device.</figref><figref num="7">The figure which shows the electronic device.</figref><figref num="8">The figure which shows the electronic device.</figref><figref num="9">(A) Model diagram showing the laminated structure of dielectrics, (B) Equivalent circuit diagram.</figref>

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention It is not limited to the following description, and it is possible for those skilled in the art to change its form and details in various ways. Easy to understand. Further, the present invention shall be construed as being limited to the description of the embodiments shown below. It is not something that can be done.

The ordinal numbers attached as the first and second numbers are used for convenience, and the process order or stacking order is used. It does not indicate. In addition, a unique name as a matter for specifying the invention in the present specification. Does not indicate.

(Embodiment 1) In the present embodiment, a semiconductor device and one embodiment of a method for manufacturing the semiconductor device will be described with reference to FIG. To do. In the present embodiment, a transistor having an oxide semiconductor film is used as an example of a semiconductor device. Is shown.

As shown in FIG. 1 (D), the transistor 410 is mounted on a substrate 400 having an insulating surface. Electrode 401, gate insulating film 402, oxide semiconductor film 403, source electrode 405a, Includes rain electrode 405b. On the oxide semiconductor film 403, the back of the oxide semiconductor film 403 A metal oxide film 407 having an antistatic function on the channel side is provided.

FIGS. 1 (A) to 1 (D) show an example of a method for manufacturing the transistor 410.

First, after forming a conductive film on the substrate 400 having an insulating surface, the first photolithography The gate electrode 401 is formed by the process. The resist mask is shaped by the inkjet method. It may be made. If the resist mask is formed by the inkjet method, no photomask is used. Therefore, the manufacturing cost can be reduced.

There are no major restrictions on the substrates that can be used for the substrate 400 having an insulating surface, but there are few. In both cases, it is necessary to have heat resistance sufficient to withstand the subsequent heat treatment. For example, moth Substrates such as lath substrates, ceramic substrates, quartz substrates, and sapphire substrates can be used. .. In addition, if it has an insulating surface, a single crystal semiconductor substrate such as silicon or silicon carbide, many Applicable to crystalline semiconductor substrates, compound semiconductor substrates such as silicon germanium, SOI substrates, etc. It is also possible to fabricate the transistors 410 on these substrates.

Further, a flexible substrate may be used as the substrate 400. When using a flexible substrate, it is flexible The transistor 410 containing the oxide semiconductor film 403 may be directly formed on the substrate, or another transistor 410 may be prepared. A transistor 410 containing an oxide semiconductor film 403 is manufactured on a manufacturing substrate, and then a flexible substrate is manufactured. It may be peeled off or transposed. In addition, in order to peel off and transfer from the manufactured substrate to the flexible substrate, A release layer may be provided between the substrate and the transistor containing the oxide semiconductor film.

An insulating film serving as a base film may be provided between the substrate 400 and the gate electrode 401. Groundwork The film has a function of preventing the diffusion of impurity elements from the substrate 400, and is a silicon nitride film and oxidation. One or more films selected from a silicon film, a silicon nitride film, or a silicon oxide film Can be formed by

The gate electrode 401 includes molybdenum, titanium, tantalum, tungsten, and aluminum. Use metal materials such as copper, neodymium, scandium, or alloy materials containing these as the main components. It can be formed in a single layer or in layers.

Next, the gate insulating film 402 is formed on the gate electrode 401. The gate insulating film 402 is Silicon oxide film, silicon nitride film, etc. using plasma CVD method or sputtering method, etc. Silicon oxide film, silicon nitride film, aluminum oxide film, aluminum nitride film, Selected from Aluminum Nitride Oxide Film, Aluminum Nitride Oxide Film, or Hafnium Oxide Film It can be formed by one or more films.

Further, impurities are removed from the oxide semiconductor film 403 of the present embodiment, and the oxide semiconductor is mainly formed. True by purifying so as not to contain impurities that serve as carrier donors other than minutes as much as possible. Use oxide semiconductors that have been made (i-type) or substantially intrinsic (i-type). Specifically, an example For example, the hydrogen concentration of the oxide semiconductor film 403 is 5 × 10.¹⁹atoms / cm³Below, desired Kuha 5 × 10¹⁸atoms / cm³Below, more preferably 5x10¹⁷atoms / c m³It is as follows. The hydrogen concentration in the oxide semiconductor film 403 described above is the mass of the secondary ion. Analysis method (SIMS: Secondary Ion Mass Spectroscopy) It is measured at. In this way, the hydrogen concentration is sufficiently reduced and the purity is high enough. Acids with reduced defect levels in the energy gap due to oxygen deficiency due to the supply of oxygen In the compound semiconductor film 403, the carrier concentration is 1 × 10.¹²/cm³Less than, preferably 1x Ten¹¹/cm³Less than, more preferably 1.45 × 10¹⁰/cm³Will be less than. For example , Off-current at room temperature (25 ° C) (here, value per unit channel width (1 μm)) is 1 00zA (1zA (Zeptoampere) is 1x10^-21A) Below, preferably 10zA or more It will be below. In this way, i-type (intrinsicized) or substantially i-type oxide semiconductors are used. Therefore, a transistor 410 having extremely excellent off-current characteristics can be obtained.

Such highly purified oxide semiconductors are extremely sensitive to interface states or interfacial charges. Therefore, the interface between the oxide semiconductor film and the gate insulating film is important. Therefore, it is highly purified High quality is required for the gate insulating film in contact with the oxide semiconductor.

For example, high-density plasma CVD using microwaves (eg frequency 2.45 GHz) is precise. It is preferable as a method for producing a gate insulating film because a high-quality insulating layer having a high dielectric strength can be formed. .. The interface state is due to the close contact between the highly purified oxide semiconductor and the high quality gate insulating film. This is because the density can be reduced and the interfacial characteristics can be improved.

Of course, if a good quality insulating film can be formed as a gate insulating film, sputtering Other film forming methods such as the method and the plasma CVD method can be applied. Also, oxide semiconductor film The film quality of the gate insulating film and the interface characteristics with the oxide semiconductor are modified by the heat treatment after the film formation. It may be an insulating film. In any case, the film quality as a gate insulating film is good. Of course, it can reduce the interface state density with oxide semiconductors and form a good interface. All you need is.

In addition, the gate insulating film 402 and the oxide semiconductor film do not contain hydrogen, hydroxyl groups and water as much as possible. Preliminary sputtering equipment as a pretreatment for film formation of oxide semiconductor film The substrate 400 on which the gate electrode 401 is formed or the gate insulating film 402 is formed in the heating chamber. Preheat the substrate 400 to remove impurities such as hydrogen and moisture adsorbed on the substrate 400. , It is preferable to exhaust. A cryopump is preferred as the exhaust means provided in the preheating chamber. I'm sorry. The preheating process may be omitted. In addition, this preheating will be done later. Substrate 400 (metal oxidation) formed up to the source electrode 405a and the drain electrode 405b It may be performed in the same manner before the film formation of the film 407).

Next, an oxide semiconductor film with a film thickness of 3 nm or more and 30 nm or less is sprinkled on the gate insulating film 402. It is formed by the tattering method. If the film thickness of the oxide semiconductor film is made too large (for example, the film thickness is 5). (0 nm or more), the transistor may become normally on, so the above The film thickness is preferable.

Before forming the oxide semiconductor film by the sputtering method, argon gas is introduced. A powdery substance adhering to the surface of the gate insulating film 402 by reverse sputtering that generates plasma. It is preferable to remove substances (also called particles or dust). What is reverse sputtering? Apply voltage to the board side using RF power supply in an argon atmosphere without applying voltage to the get side. This is a method of modifying the surface by forming plasma in the vicinity of the substrate. In addition, in the argon atmosphere Alternatively, nitrogen, helium, oxygen or the like may be used.

The oxide semiconductor used for the oxide semiconductor film is In-Sn-G, which is a quaternary metal oxide. a-Zn-O oxide semiconductors and In-Ga-Zn-O oxides, which are ternary metal oxides Semiconductors, In-Sn-Zn-O oxide semiconductors, In-Al-Zn-O oxide semiconductors, Sn-Ga-Zn-O oxide semiconductor, Al-Ga-Zn-O oxide semiconductor, Sn-A l-Zn-O oxide semiconductors and In-Zn-O oxide semiconductors, which are binary metal oxides , Sn-Zn-O oxide semiconductors, Al-Zn-O oxide semiconductors, Zn-Mg-O acids Compound semiconductors, Sn-Mg-O oxide semiconductors, In-Mg-O oxide semiconductors, In-G aO-based oxide semiconductors, In-O-based oxide semiconductors, Sn-O-based oxide semiconductors, Zn-O A system oxide semiconductor or the like can be used. In addition, SiO is added to the oxide semiconductor.₂Including May be good. Here, for example, the In-Ga-Zn-O-based oxide semiconductor is indium (In). ), Gallium (Ga), and zinc (Zn). The ratio does not matter. It may also contain elements other than In, Ga and Zn.

In addition, the oxide semiconductor film has the chemical formula InMO.₃(ZnO)_mThe thin film represented by (m&gt; 0) Can be used. Here, M is one or one selected from Ga, Al, Mn and Co. Indicates multiple metal elements. For example, as M, Ga, Ga and Al, Ga and Mn, or G There are a and Co and so on.

When using an In-Ga-Zn-O material as the oxide semiconductor, use it as the target. For example, as a composition ratio, In₂O₃: Ga₂O₃: ZnO = 1: 1: 1 [mol number Ratio] oxide targets can be used. Also, for the material and composition of this target Not limited, for example, In₂O₃: Ga₂O₃: ZnO = 1: 1: 2 [mol number ratio] acid A compound target may be used.

When using an In-Zn-O material as the oxide semiconductor, the target set to be used The composition ratio is the atomic number ratio, In: Zn = 50: 1 ~ 1: 2 (when converted to the molar ratio, In₂O₃: ZnO = 25: 1 ~ 1: 4), preferably In: Zn = 20: 1 ~ 1: 1 (in molar ratio) When converted, In₂O₃: ZnO = 10: 1 ~ 1: 2), more preferably In: Zn = 1 5: 1 ~ 1.5: 1 (In when converted to molar ratio₂O₃: ZnO = 15: 2 ~ 3: 4) and To do. For example, the target used to form an In-Zn-O oxide semiconductor has an atomic number ratio. When In: Zn: O = X: Y: Z, Z&gt; 1.5X + Y.

The filling rate of the target is 90% or more and 100% or less, preferably 95% or more and 99.9%. It is as follows. By using a target with a high filling rate, the oxide semiconductor film formed can be made dense. It can be a dense film.

In this embodiment, an In-Ga-Zn-O oxide target is used as the oxide semiconductor film. The film is formed by the sputtering method. The oxide semiconductor film is a rare gas (typically a). Lugon) Sputtering method in an atmosphere, an oxygen atmosphere, or a mixed atmosphere of a rare gas and oxygen Can be formed by

The sputter gas used for forming the oxide semiconductor film is hydrogen, water, a hydroxyl group, or water. It is preferable to use a high-purity gas from which impurities such as raw materials have been removed.

To form an oxide semiconductor film, the substrate 400 is held in a film forming chamber kept under reduced pressure, and the substrate temperature is increased. The degree is 100 ° C or more and 600 ° C or less, preferably 200 ° C or more and 400 ° C or less. Board 4 Impurity concentration contained in the oxide semiconductor film formed by forming a film while heating 00 Can be reduced. In addition, damage due to sputtering is reduced. And film formation While removing the residual moisture in the room, hydrogen and sputter gas from which the moisture was removed were introduced, and the above-mentioned tar An oxide semiconductor film is formed on the substrate 400 using a get. Removes residual moisture in the film formation chamber In order to use adsorption type vacuum pumps such as cryopumps, ion pumps, titanium subs. It is preferable to use a remation pump. Also, the exhaust means calls the turbo pump. It may be the one to which a dot trap is added. An example of a film formation chamber exhausted using a cryopump For example, hydrogen atom, water (H₂Compounds containing hydrogen atoms such as O) (more preferably containing carbon atoms) Impure contained in the oxide semiconductor film formed in the film forming chamber because the compound is exhausted. The concentration of things can be reduced.

As an example of film formation conditions, the distance between the substrate and the target is 100 mm, and the pressure is 0.6 Pa. , Direct current (DC) power supply 0.5kW, Oxygen (oxygen flow rate ratio 100%) atmospheric conditions are applied Is done. If a pulsed DC power supply is used, powdery substances (particles, particles) generated during film formation It is preferable because the film thickness distribution can be reduced and the film thickness distribution becomes uniform.

Next, the oxide semiconductor film is subjected to a second photolithography step to form an island-shaped oxide semiconductor film 4 Process to 41 (see Fig. 1 (A)). Further, in order to form an island-shaped oxide semiconductor film 441. The resist mask of the above may be formed by an inkjet method. Ink jet mask Since the photomask is not used when the photomask is formed by the method, the manufacturing cost can be reduced. This will , An oxide semiconductor film in a region overlapping the gate electrode can be formed on the gate insulating film. ..

The etching of the oxide semiconductor film here is wet etching even with dry etching. You may use both. For example, used for wet etching of oxide semiconductor films As the etching solution, a solution obtained by mixing phosphoric acid, acetic acid and nitric acid can be used. Ma Alternatively, ITO 07N (manufactured by Kanto Chemical Co., Inc.) may be used.

Next, on the gate insulating film 402 and the oxide semiconductor film 441, the source electrode and the drain electric current are applied. Form a conductive film for forming poles (including wiring formed in the same layer). Source Examples of the conductive film used for the electrode and the drain electrode include Al, Cr, Cu, Ta, and Ti. , Mo, a metal film containing an element selected from W, or a metal nitride containing the above-mentioned elements as components. A film (titanium nitride film, molybdenum nitride film, tungsten nitride film) or the like can be used. In addition, Ti, Mo, W, etc. on one or both of the lower side or upper side of the metal film such as Al, Cu, etc. Refractory metal film or their metal nitride film (titanium nitride film, molybdenum nitride film, tanned nitride film It may be configured by laminating a gustene film). Also used for source and drain electrodes The conductive film may be formed of a conductive metal oxide. Oxidation as a conductive metal oxide Ndium (In₂O₃), Tin oxide (SnO)₂), Zinc oxide (ZnO), indium oxide Tin oxide alloy (In₂O₃SnO₂, ITO is abbreviated), indium tin oxide zinc oxide Gold (In₂O₃ZnO) or these metal oxide materials containing silicon oxide Can be used.

The materials for the source electrode and drain electrode are the electron affinity of the oxide semiconductor used and the metallic acid. It is preferable to determine it in consideration of the electron affinity of the chemical film. That is, the source electrode and dray The work function of the electrode material is W [eV], and the electron affinity of the oxide semiconductor is φ.₁[eV], metal The electron affinity of the oxide film is φ₂When set to [eV], φ₂+0.4 &lt;W &lt;(φ₁+0.5), Preferably, (φ₂+0.9) &lt;W &lt;(φ₁+0.4), it is preferable to satisfy the relationship I'm sorry. For example, as an oxide semiconductor and a metal oxide film, the electron affinity is 4.5 eV, respectively. , If 3.5eV material is used, the material of the source electrode and drain electrode should be The function is greater than 3.9eV and less than 5.0eV, preferably greater than 4.4eV It is preferable to use a metal or an intermetallic compound having a value of less than 4.9 eV. Then Metal oxidation from source electrode 405a and drain electrode 405b in transistor 410 It can prevent the injection of electrons into the membrane 407, suppress the leakage current, and the oxide semiconducting. Good electrical characteristics can be obtained at the junction between the body membrane and the source electrode and drain electrode. .. Materials having such a work function include, for example, molybdenum nitride and tongue nitridant. And so on. These materials are preferable because they are also excellent in heat resistance. Na Oh, from the above relational expression, φ₂&lt;(φ₁+0.1), preferably φ₂&lt;(φ₁-0.5) and Is derived, but more preferably φ₂&lt;(φ₁-0.9) It is good.

By the third photolithography step, on the conductive film used for the source electrode and drain electrode A resist mask is formed and selectively etched to source electrode 405a and drain electricity. After forming pole 405b, the resist mask is removed (see Figure 1 (B)).

For exposure during resist mask formation in the third photolithography process, ultraviolet rays or KrF It is advisable to use laser light or ArF laser light. Adjacent source electrodes on the oxide semiconductor film 441 It is formed later by the distance between the lower end of the 405a and the lower end of the drain electrode 405b. The channel length L of the Langista is determined. Exposure with a channel length of less than L = 25 nm In the case of extreme ultraviolet rays (Extreme Ult), which have extremely short wavelengths of several nm to several tens of nm. When forming a resist mask in the third photolithography process using raviolet) It is good to perform exposure. Exposure with ultra-ultraviolet rays has a high resolution and a large depth of focus. Therefore, later The channel length L of the transistor formed in can be set to 10 nm or more and 1000 nm or less. It is possible, and the operating speed of the circuit can be increased.

In addition, in order to reduce the number of photomasks and the number of steps used in the photolithography process, transmission is performed. Registrar formed by a multi-tone mask, which is an exposure mask in which the emitted light has multiple intensities. The etching step may be performed using a desk. Registrar formed using a multi-tone mask The desk has a shape with multiple film thicknesses, and the shape can be further deformed by etching. It can be used in multiple etching processes to process different patterns. .. Therefore, one multi-tone mask can handle at least two different patterns. It is possible to form a resist mask to be used. Therefore, the number of exposure masks can be reduced. Since the corresponding photolithography process can be reduced, the process can be simplified.

It should be noted that the oxide semiconductor film is used when etching the conductive film used for the source electrode and the drain electrode. It is hoped that the etching conditions will be optimized so that the 441 is not etched and split. Get caught. However, only the conductive film is etched, and the oxide semiconductor film 441 is completely etched. It is difficult to obtain the condition that the conductive film is not etched, and the oxide semiconductor film 4 is used when etching the conductive film. Only a part of 41 is etched to form an oxide semiconductor film having grooves (recesses). To.

In the present embodiment, a Ti film is used as a conductive film used for the source electrode and the drain electrode, and an acid is used. Since an In-Ga-Zn-O oxide semiconductor was used for the compound semiconductor film 441, Etchan Ammonia overwater (31 wt% hydrogen peroxide solution: 28 wt% ammonia water: water = 5: 2: 2) is used.

Then N₂O, N₂Or, plasma treatment using a gas such as Ar is performed and it is exposed. Hydrogen, water, etc. adhering to the surface of the oxide semiconductor film may be removed. Perform plasma processing In that case, a part of the oxide semiconductor film 441 without being exposed to the atmosphere following the plasma treatment. It is desirable to form a metal oxide film 407 in contact with the metal oxide film 407.

Next, the source electrode 405a and the drain electrode 405b are covered, and the oxide semiconductor film 4 is used. A metal oxide film 407 is formed in contact with a part of 41 (see FIG. 1 (C)). The metal oxide film The film thickness of 407 is thicker than that of the oxide semiconductor film 441. The metal oxide film 407 is a half oxide The back channel side of the conductor film 441, that is, the source electrode 405a and the drain electrode 405b. It is a film that comes into contact with the oxide semiconductor film 441 between them and removes the electric charge accumulated at the interface.

Due to the charge accumulated in the source electrode 405a or the drain electrode 405b, the source electrode 40 Positive charge is transferred from 5a or drain electrode 405b to the oxide semiconductor film, and the oxide half The interface on the back channel side of the conductor film may be charged. In particular, electrical transmission of oxide semiconductor film If the conductivity and the electrical conductivity of the material layer in contact with the back channel side of the oxide semiconductor film are different, Charges flow to the oxide semiconductor film, and the charges are captured at the interface and combined with hydrogen in the oxide semiconductor film. Becomes a donor center at the interface. As a result, the characteristics of the transistor will fluctuate. Problems will occur. Therefore, reduction of hydrogen in the oxide semiconductor film and charging of the oxide semiconductor film Both prevention are important.

The difference between the band gap of the oxide semiconductor film and the band gap of the metal oxide film is 3 eV. Less than is preferable. For example, an In-Ga-Zn-O oxide semiconductor is used as an oxide semiconductor film. When silicon oxide or aluminum oxide is used as the metal oxide film, In-Ga- The bandgap of Zn-O oxide semiconductors is 3.15 eV, silicon oxide and aluminum oxide. Since the bandgap of nium is 8 eV, the above-mentioned problems may occur. Also, When a film containing a nitride (for example, a silicon nitride film) is used instead of the metal oxide film, the nitride is produced. The electrical conductivity of the oxide semiconductor film fluctuates due to the contact between the containing film and the oxide semiconductor film. There is a risk.

Therefore, the metal oxide film 407 is positively charged on the back channel side of the oxide semiconductor film. Even if it does, it is preferable that it has the property of quickly removing it. However, metal oxide film 407 The material used in the above has a hydrogen content equal to or less than that of the oxide semiconductor film, and is half an oxide. Even if it is more than the conductor film, it is a material that is not more than an order of magnitude, and its energy The material is preferably a material having equal to or greater than the material of the oxide semiconductor film. I'm sorry.

In one aspect of the invention, gallium oxide, such as gallium oxide (GaO), as the metal oxide film The case of using x (X&gt; 0)) will be described. The physical characteristics of gallium oxide are, for example, vans. The gap is 3.0eV to 5.2eV (for example, 4.9eV), the permittivity is 8 to 20, and the electron. The affinity is 3.5 eV, and the physical property values of In-Ga-Zn-O oxide semiconductors are, for example, The bandgap is 3.15 eV, the permittivity is 15, the electron affinity is 3.5 eV, and the oxide is It is preferable because the difference in physical properties between lithium and In-Ga-Zn-O oxide semiconductors is small. Good. Also, gallium oxide has a wide bandgap of approximately 4.9 eV. , Has translucency in the visible light region. Also, use gallium oxide as a metal oxide film. As a result, the contact resistance between the In-Ga-Zn-O-based oxide semiconductor film and the gallium oxide film is reduced. It is preferable because it can be reduced. When gallium oxide is used as the metal oxide film, In In addition to -Ga-Zn-O oxide semiconductors, In-Ga-O oxides as oxide semiconductor materials It is preferable to use a semiconductor or a Ga-Zn-O oxide semiconductor.

In this way, by using a metal oxide film having an antistatic function, the oxide semiconductor film can be formed. It is possible to suppress the accumulation of electric charge on the back channel side. In addition, the metal oxide film is an oxide semiconductor film. By providing it on the upper surface of the oxide semiconductor film, a positive charge is charged on the back channel side of the oxide semiconductor film. Even if it does, it can be removed quickly. In addition, by using the metal oxide film 407 , It is possible to prevent the generation of parasitic channels on the back channel side of the oxide semiconductor film 403. To. This makes it possible to suppress fluctuations in electrical characteristics such as the electrical conductivity of oxide semiconductor films. Therefore, the reliability of the transistor can be improved.

It is preferable to use a gallium oxide film as the metal oxide film. Gallium oxide film is spatter It can be obtained by a welding method, a CVD method, a vapor deposition method, or the like. Gallium oxide film is oxygen and gas It has a bandgap of about 4.9 eV, depending on the composition ratio of lithium, and has an odor in the visible light range. It is translucent.

In this specification, gallium oxide may be referred to as GaOx (x&gt; 0). For example, Ga If Ox has a crystal structure, Ga with x = 1.5₂O₃It has been known.

In this embodiment, the metal oxide film 407 is sputtered using a pulsed direct current (DC) power supply. A gallium oxide film obtained by the method is used. The target used in the sputtering method It is preferable to use a gallium oxide target. Also, the oxide semiconductor used Indium or zinc is appropriately added to the metal oxide film 407 according to the electrical conductivity of the film to conduct electrical transmission. The lead may be adjusted. For example, a target made by adding indium or zinc to gallium oxide. Contains 0.01 to 5 atomic% of indium or zinc by sputtering method Form a film. Electricity of metal oxide film 407 by adding indium or zinc By improving the conductivity and bringing it closer to the electrical conductivity of the oxide semiconductor film 403, charge accumulation can be achieved. It can be further reduced.

In particular, when an In-Ga-Zn-O film is used as the oxide semiconductor film, the metal oxide film 40 It contains a gallium element common to GaOx used as 7, and is preferred because it is compatible with the material. I'm sorry.

The metal oxide film 407 is preferably formed by a method that does not mix impurities such as water and hydrogen. Good. When hydrogen is contained in the metal oxide film 407, the hydrogen invades the oxide semiconductor film and also Is the extraction of oxygen in the oxide semiconductor film by hydrogen, which causes the back channel of the oxide semiconductor film. There is a risk that the resistance will be reduced (n-shaped) and parasitic channels will be formed. Therefore, Do not use hydrogen in the film formation method so that the metal oxide film 407 is a film that does not contain hydrogen as much as possible. It is important to be.

In the present embodiment, the metal oxide film 407 has a film thickness of more than 10 nm and an oxide semiconductor. A gallium oxide film having a film thickness equal to or larger than that of the film 441 is formed by a sputtering method. like this By making the thickness of the metal oxide film 407 thicker than that of the oxide semiconductor film 441, the metal oxide film 4 This is because 07 can efficiently remove the electric charge. The substrate temperature during film formation is above room temperature It should be above 300 ° C or less. The film formation of the gallium oxide film by the sputtering method is a rare gas. In an atmosphere (typically argon), in an oxygen atmosphere, or in a mixed atmosphere of rare gas and oxygen Can be done at.

Residual moisture in the film formation chamber of the metal oxide film 407 was removed in the same manner as when the oxide semiconductor film was formed. For this purpose, it is preferable to use an adsorption type vacuum pump (cryopump or the like). Cryo Low concentration of impurities contained in the metal oxide film 407 formed in the film forming chamber exhausted using a pump Can be reduced. It also serves as an exhaust means for removing residual moisture in the film formation chamber of the metal oxide film 407. Alternatively, it may be a turbo pump with a cold trap added.

The sputtering gas used for forming the metal oxide film 407 is hydrogen, water, a hydroxyl group, or It is preferable to use a high-purity gas from which impurities such as hydrides have been removed.

Further, the metal oxide film 407 is at least the channel forming region of the oxide semiconductor film, the source electrode 4 It is sufficient to cover 05a and drain electrode 405b, and if necessary, select metal oxide film 407. It may be optionally removed. For etching the gallium oxide film used in this embodiment, Known wet etching or known dry etching can be used. For example Wet etching with hydrofluoric acid solution or nitric acid.

Next, the oxide semiconductor film 441 was in contact with the metal oxide film 407 and a part (channel forming region). Heat treatment is performed in this state (see Fig. 1 (C)).

The temperature of the heat treatment is 250 ° C or more and 650 ° C or less, preferably 450 ° C or more and 600 ° C or less. Alternatively, it should be less than the distortion point of the substrate. For example, introducing a substrate into an electric furnace, which is one of the heat treatment devices. Then, the oxide semiconductor film is heat-treated at 450 ° C for 1 hour under a nitrogen atmosphere.

The heat treatment device is not limited to an electric furnace, and heat conduction or heat from a heating element such as a resistance heating element is used. A device that heats the object to be processed by radiation may be used. For example, GRTA (Gas R) apid Thermal Anneal) device, LRTA (Lamp Rapid T) RTA (Rapid Thermal Anne) for hermal Anneal equipment, etc. al) Equipment can be used. LRTA equipment is halogen lamp, metal halide lamp Amp, xenon arc lamp, carbon arc lamp, high pressure sodium lamp, high pressure mercury A device that heats an object to be processed by the radiation of light (electromagnetic waves) emitted from a lamp such as a lamp. To. The GRTA device is a device that performs heat treatment using high-temperature gas. For hot gas, Rare gas such as argon, or non-reacting with the object to be treated by heat treatment such as nitrogen An active gas is used. If a GRTA device is used as the heat treatment device, its Due to the short heat treatment time, the substrate is heated in an inert gas heated to a high temperature of 650 ° C to 700 ° C. You may.

The heat treatment is nitrogen, oxygen, ultra-dry air (water content is 20 ppm or less, preferably 1 pp). M or less, preferably 10 ppb or less air), or rare gas (argon, helium, etc.) It may be performed in the above atmosphere, but water in the above atmosphere such as nitrogen, oxygen, ultra-dry air, or rare gas. , Hydrogen and the like are preferably not contained. In addition, nitrogen, oxygen, and even nitrogen to be introduced into the heat treatment equipment. Or the purity of the rare gas is 6N (99.9999%) or more, preferably 7N (99.9999%). 9%) or more (that is, the impurity concentration should be 1 ppm or less, preferably 0.1 ppm or less). Is preferable.

Further, the heat treatment was performed in a state where the oxide semiconductor film and the metal oxide film 407 containing oxygen were in contact with each other. Therefore, the main component material that constitutes the oxide semiconductor, which is reduced at the same time by the impurity removal process. Oxygen, which is one of the above, can be supplied from the metal oxide film 407 containing oxygen to the oxide semiconductor film. it can. Thereby, the charge capture center in the oxide semiconductor film can be reduced. that's all In the process of (1), a highly purified and electrically i-type (intrinsic) oxide semiconductor film 403 is obtained. In addition, by this heat treatment, impurities are also removed from the metal oxide film 407 at the same time, resulting in high purity. It can be.

In the highly purified oxide semiconductor film 403, there are very few carriers derived from the donor, and there are very few carriers. Carrier concentration is 1x10¹⁴/cm³Less than, preferably 1x10¹²/cm³Less than, more Preferably 1x10¹¹/cm³Is less than.

The transistor 410 is formed by the above steps (see FIG. 1 (D)). Transistor 410 Is an oxide semiconducting of impurities such as hydrogen, water, hydroxyl groups or hydrides (also called hydrides). A transistor containing an oxide semiconductor film 403 that has been intentionally removed from the body membrane and purified. To. Therefore, the transistor 410 is electrically stable because the fluctuation of electrical characteristics is suppressed. is there.

Further, in addition to the above heat treatment, another heat treatment may be performed. For example, oxide semiconductor film 4 After forming 41, heat treatment (first heat treatment) was performed to form a metal oxide film 407. Later, further heat treatment (second heat treatment) may be performed. In this case, the first heat treatment For example, heating is performed in an atmosphere of an inert gas, and an atmosphere of oxygen (at least an atmosphere containing oxygen) is used. It can be a process of cooling by (down). Applying such a first heat treatment Therefore, dehydration and oxidation of the oxide semiconductor film can be preferably performed.

Further, the heat treatment may be further performed after the second heat treatment. For example, in the atmosphere, 100 The heat treatment may be performed at ° C or higher and 200 ° C or lower, and for 1 hour or longer and 30 hours or lower. This heating process The reason is that it may be heated while maintaining a constant heating temperature, or from room temperature, 100 ° C or more and 200 ° C or less. The temperature may be raised to the heating temperature of the above and the temperature may be lowered from the heating temperature to the room temperature multiple times. ..

Further, the transistor 410 using the oxide semiconductor film 403 has a relatively high field effect mobility. Therefore, high-speed driving is possible. Therefore, the above transistor is used for the pixel part. With, it is possible to provide a high-quality image. It also contains a highly purified oxide semiconductor film. Since the drive circuit unit and the pixel unit having the transistor can be formed on the same substrate, the semiconductor device The number of parts can be reduced.

Further, in the transistor 410 having the metal oxide film 407, the oxide semiconductor film 403 is backed up. It is possible to prevent the occurrence of parasitic channels on the channel side. In addition, transistor 41 Preventing the generation of parasitic channels on the back channel side of the oxide semiconductor film 403 at 0 And, since the fluctuation of the threshold voltage can be suppressed, the transistor with improved reliability Can be.

By the way, in the transistor 410 shown in FIG. 1 (D), the oxide semiconductor film 403 and Two layers of dielectrics are in contact with the metal oxide film 407. Two different layers of dielectric are laminated If so, the permittivity of the first layer (oxide semiconductor film 403 in the transistor 410) is changed. ε₁, Conductivity σ₁, Thickness d₁And the second layer (metal oxidation in transistor 410) The permittivity of film 407) is ε₂, Conductivity σ₂, Thickness d₂When, the lamination of the two layers is shown in Fig. 9 ( It can be represented by the model diagram of A). In FIG. 9A, S represents an area. Also , The model diagram of FIG. 9 (A) can be replaced with the equivalent circuit of FIG. 9 (B). C in the figure₁Is the capacity value of the first layer, G₁Is the resistance value of the first layer, C₂Is the capacity value of the second layer, G₂Is 2 layers Represents the resistance value of each eye. Here, when a voltage V is applied to the two layers, the interface between the two layers is t seconds later. It is assumed that the electric charge Q represented by the following equation (1) is accumulated in.

<maths num="1"><img file="JP2012256902A_D0001.tif" /></maths>

In the transistor 410 shown in FIG. 1 (D), the interface on which the above-mentioned charge Q is accumulated is oxidized. Corresponds to the back channel side of the semiconductor film 403, and the permittivity or electrical transfer of the metal oxide film 407. By appropriately setting the conductivity or the film thickness of the metal oxide film 407, the interface on the back channel side The charge Q accumulated in can be reduced.

Here, when the equation (1) is modified, it is expressed by the following equations (2) and (3).

<maths num="2"><img file="JP2012256902A_D0002.tif" /></maths>

From equations (2) and (3), in order to reduce the charge Q, the following 4 articles (A) to (D) The case can be assumed. Condition (A) τ_iTo be very large. Condition (B) V₂Close to zero, that is, G₂G₁Make it much larger. Condition (C) C₂To approach zero. Condition (D) τ₁Τ₂Get closer to.

Under condition (A), τ_iTo make it very large, τ_i= (C₁+ C₂) / (G₁+ G₂), So (C₁+ C₂) To (G₁+ G₂) Can be much larger. here, C₁, G₁Is a parameter of the oxide semiconductor film 403, so by the metal oxide film 407 To reduce the charge Q, C₂Needs to be large. However, C₂= ε₂S / d₂More ε₂At C₂When is increased, Q becomes larger than Eq. (2), causing a contradiction. .. That is, τ_iThe charge Q cannot be adjusted with.

In condition (B), V₂From equation (3), G₂&gt;&gt; G₁If you meet Good. G₁Is a parameter of the oxide semiconductor film 403, so by the metal oxide film 407 To reduce the charge Q, G₂Needs to be large. Specifically, G₂= σ₂S / d₂Therefore, d₂To make it smaller or σ₂The larger material will be selected. Deer And d₂Reduction of C₂= ε₂S / d₂More C₂Becomes larger and Q becomes larger as in condition (A) It cannot be adopted because it becomes large. Also, σ₂Is large, the metal oxide film 407 It means that the electrical conductivity is higher than that of the oxide semiconductor film 403, which causes leakage current generation and noise. It cannot be adopted due to the high risk of yoto.

In condition (C), C₂To make C very small₂= ε₂S / d₂From d₂Large Crush or ε₂You will choose a material with a small size.

Also, under condition (D), τ₁Τ₂To get closer to τ₁= ε₁/ σ₁, Tau₂= ε₂/ σ₂Therefore, ε₁/ σ₁ ε₂/ σ₂You just have to choose the film that will be. This is C₁/ G₁ C₂/ G₂Is equivalent to.

Therefore, in order to effectively prevent the accumulation of charge Q, the film thickness of the metal oxide film 407 (d)₂), Or as a material for the metal oxide film 407, the permittivity (ε)₂) Small material, good Furthermore, a material smaller than the oxide semiconductor film 403 (for example, a dielectric constant ε of 8 or more and 20 or less). It is preferable to select a material). Or ε₁/ σ₁ ε₂/ σ₂(ε₁Is an oxide semiconduct Permittivity of the body, σ₁Is close to the physical property value of the oxide semiconductor film so that it becomes the conductivity of the oxide semiconductor). It is preferable to select a suitable material as the metal oxide film.

As described above, in the transistor 410 having the metal oxide film 407 having an antistatic function, It is possible to suppress the accumulation of electric charges on the back channel side of the oxide semiconductor film. Also, metal oxidation By providing the film on the upper surface of the oxide semiconductor film, it can be placed on the back channel side of the oxide semiconductor film. Even if the lath is charged, it can be quickly removed. Also, metal oxide film 407 In the transistor 410 having the above, the parasitic cha on the back channel side of the oxide semiconductor film 403 It is possible to prevent the generation of flannel. Further, in the transistor, the oxide semiconductor film is formed. Suppresses fluctuations in threshold voltage by preventing the generation of parasitic channels on the back channel side be able to. As a result, fluctuations in the electrical conductivity of the oxide semiconductor film can be suppressed. Therefore, the reliability of the transistor can be improved.

As described above, a semiconductor device using an oxide semiconductor having stable electrical characteristics is provided. be able to. Therefore, it is possible to provide a highly reliable semiconductor device.

As described above, the configurations, methods, etc. shown in the present embodiment are suitable with the configurations, methods, etc. shown in other embodiments. It can be used in any combination.

(Embodiment 2) In this embodiment, another embodiment of the method for manufacturing a semiconductor device will be described. Same as the above embodiment A part or a part having a similar function and a step can be performed in the same manner as in the above embodiment. Therefore, the repeated description will be omitted. Further, detailed description of the same part will be omitted.

In the present embodiment, in the method for manufacturing the transistor 410 shown in the first embodiment, oxidation is performed. An example of heat-treating an oxide semiconductor film before forming a metal oxide film 407 in contact with a semiconductor film. Is shown.

This heat treatment is performed after the oxide semiconductor film is formed and before the metal oxide film 407 is formed. If this is the case, the island-shaped oxide semiconductor film may be applied to the oxide semiconductor film before processing, and the source electrode 4 It may be applied either before or after the formation of 05a and the drain electrode 405b.

The temperature of the heat treatment is 250 ° C or more and 650 ° C or less, preferably 450 ° C or more and 600 ° C or less. To do. For example, a substrate is introduced into an electric furnace, which is one of the heat treatment devices, and the oxide semiconductor film is used. Heat treatment is performed at 450 ° C for 1 hour in a nitrogen atmosphere. After heat treatment, come into contact with the atmosphere It is preferable to form a metal oxide film without forming a metal oxide film and prevent re-mixing of water and hydrogen into the oxide semiconductor film. I.

The heat treatment device is not limited to an electric furnace, and heat conduction or heat from a heating element such as a resistance heating element is used. A device that heats the object to be processed by radiation may be used. For example, GRTA device, LRT An RTA device such as the A device can be used. The GRTA device is used as a heat treatment device. When used, the heat treatment time is short, so it is inactive when heated to a high temperature of 650 ° C to 700 ° C. The substrate may be heated in a sex gas.

The heat treatment is nitrogen, oxygen, ultra-dry air (water content is 20 ppm or less, preferably 1 pp). M or less, preferably 10 ppb or less air), or rare gas (argon, helium, etc.) It may be performed in the above atmosphere, but water in the above atmosphere such as nitrogen, oxygen, ultra-dry air, or rare gas. , Hydrogen and the like are preferably not contained. In addition, nitrogen, oxygen, and even nitrogen to be introduced into the heat treatment equipment. Or the purity of the rare gas is 6N (99.9999%) or more, preferably 7N (99.99999). %) Or more (that is, the impurity concentration should be 1 ppm or less, preferably 0.1 ppm or less). preferable.

This heat treatment reduces impurities such as water and hydrogen in the oxide semiconductor film. Can be done.

Furthermore, we decided to perform heat treatment in a state where the oxide semiconductor film and the metal oxide film containing oxygen are in contact with each other. Therefore, the main component material constituting the oxide semiconductor, which is reduced at the same time by the impurity removal process. Oxygen, which is one of the agents, can be supplied to the oxide semiconductor film from the metal oxide film containing oxygen. To.

Therefore, the oxide semiconductor film is heat-treated before the formation of the metal oxide film, and the metal oxide film is formed. If heat treatment is performed after the formation, impurities such as water and hydrogen are further eliminated, i-type (intrinsic half). An oxide semiconductor film as close as possible to a conductor) or i-type can be obtained.

Therefore, the transistor containing the highly purified oxide semiconductor film suppresses the fluctuation of electrical characteristics. And is electrically stable.

Further, the transistor having a metal oxide film is a parasitic chip on the back channel side of the oxide semiconductor film. It is possible to prevent the generation of channel.

As described above, a semiconductor device using an oxide semiconductor having stable electrical characteristics is provided. be able to. Therefore, it is possible to provide a highly reliable semiconductor device.

As described above, the configurations, methods, etc. shown in the present embodiment are suitable with the configurations, methods, etc. shown in other embodiments. It can be used in any combination.

(Embodiment 3) It has a display function using the transistor shown as an example in either 1 or 2 of the embodiment. A semiconductor device (also called a display device) can be manufactured. In addition, the drive including the transistor A part or the whole of the dynamic circuit is integrally formed on the same substrate as the pixel part to form a system on panel. Can be done.

In FIG. 2A, the pixel portion 4002 provided on the first substrate 4001 is surrounded. A sealing material 4005 is provided and sealed by a second substrate 4006. Figure 2( In A), the area surrounded by the sealing material 4005 on the first substrate 4001 Is formed of a single crystal semiconductor film or a polycrystalline semiconductor film on a separately prepared substrate in different regions. The scanning line drive circuit 4004 and the signal line drive circuit 4003 are mounted. Also formed separately The signal line drive circuit 4003 and the scan line drive circuit 4004 or the pixel section 4002 Various signals and potentials are available on FPC (Flexible printed circuit). ) Supplied from 4018a and 4018b.

In FIGS. 2 (B) and 2 (C), the pixel portion 4002 provided on the first substrate 4001. A sealing material 4005 is provided so as to surround the scanning line drive circuit 4004. Further, a second substrate 4006 is provided on the pixel unit 4002 and the scanning line drive circuit 4004. There is. Therefore, the pixel unit 4002 and the scanning line drive circuit 4004 are the first substrate 4001 and the same. It is sealed together with the display element by the material 4005 and the second substrate 4006. Figure 2 In (B) and FIG. 2 (C), it is surrounded by the sealing material 4005 on the first substrate 4001. Single crystal semiconductor film or polycrystalline semi-film on a separately prepared substrate in a region different from the region A signal line drive circuit 4003 formed of a conductor film is mounted. Fig. 2 (B) and Fig. 2 (C In), the separately formed signal line drive circuit 4003 and the scanning line drive circuit 4004 are also used. Various signals and potentials given to the pixel unit 4002 are supplied from FPC4018. ..

Further, in FIGS. 2 (B) and 2 (C), the signal line drive circuit 4003 is separately formed, and the first An example of mounting on the board 4001 of the above is shown, but the present invention is not limited to this configuration. Scanning line drive The circuit may be formed and mounted separately, or a part of the signal line drive circuit or one of the scan line drive circuits. Only the part may be formed separately and mounted.

The method of connecting the separately formed drive circuit is not particularly limited, and COG (Ch) is not particularly limited. ip On Glass) method, wire bonding method, or TAB (Tape A) The utomated Bonding) method or the like can be used. Figure 2 (A) shows C This is an example of mounting the signal line drive circuit 4003 and the scanning line drive circuit 4004 by the OG method. Fig. 2 (B) is an example of mounting the signal line drive circuit 4003 by the COG method, and Fig. 2 (C). ) Is an example of mounting the signal line drive circuit 4003 by the TAB method.

Further, the display device includes a panel in which the display element is sealed and a controller on the panel. Includes modules that are equipped with ICs and the like.

The display device in the present specification is an image display device, a display device, or an optical device. Refers to the source (including lighting equipment). Also, if a connector, such as FPC or TAB tape, Or a module with TCP attached, a printed wiring board at the end of TAB tape or TCP An IC (integrated circuit) is directly mounted on the provided module or display element by the COG method. All the modules are included in the display device.

In addition, the pixel section and scanning line drive circuit provided on the first substrate 4001 have multiple transistors. Apply a transistor that has a number and is shown as an example in either Embodiment 1 or 2. be able to.

The display elements provided in the display device include a liquid crystal element (also called a liquid crystal display element) and a light emitting element (also called a liquid crystal display element). (Also referred to as a light emitting display element), can be used. The light emitting element depends on the current or voltage. Elements whose brightness is controlled are included in the category, and specifically, inorganic EL (Electro). Luminescence), organic EL, etc. are included. Also, electrical work such as electronic ink A display medium whose contrast changes depending on the application can also be applied.

A form of a semiconductor device will be described with reference to FIGS. 3 to 5. 3 to 5 are shown in FIG. 2 ( Corresponds to the cross-sectional view in MN of B).

As shown in FIGS. 3 to 5, the semiconductor device uses the connection terminal electrode 4015 and the terminal electrode 4016. The connection terminal electrode 4015 and the terminal electrode 4016 are the terminals of the FPC 4018. Is electrically connected to and through the anisotropic conductive film 4019.

The connection terminal electrode 4015 is formed of the same conductive film as the first electrode layer 4030, and the terminal electrode 4 016 is the same conductive film as the source electrode and drain electrode of transistors 4010 and 4011. Is formed of.

Further, the pixel unit 4002 provided on the first substrate 4001 and the scanning line drive circuit 4004 It has a plurality of transistors, and in FIGS. 3 to 5, the transition included in the pixel portion 4002. Illustrate the star 4010 and the transistor 4011 included in the scanning line drive circuit 4004. There is. In Fig. 3, metal oxidation with antistatic function is performed on transistors 4010 and 4011. A film 4020 is provided, and in FIGS. 4 and 5, an insulating layer 4021 is further provided. Na The insulating film 4023 is an insulating film that functions as a base film.

In the present embodiment, the transistor 4010 and the transistor 4011 are used as the first embodiment. Alternatively, the transistor shown in either 2 can be applied.

In transistor 4010 and transistor 4011, the oxide semiconductor film is laminated on top. By performing heat treatment after forming the metal oxide film 4020 to be formed, hydrogen, moisture, and water Impurities such as acid groups or hydrides (also called hydrogen compounds) are intentionally eliminated from the oxide semiconductor film. It is an oxide semiconductor film that has been removed and purified.

In addition, heat treatment is performed with the oxide semiconductor film and the metal oxide film 4020 containing oxygen in contact with each other. Therefore, the main component material that constitutes the oxide semiconductor, which is reduced at the same time by the impurity removal process. Supplying oxygen, which is one of the agents, from the metal oxide film 4020 containing oxygen to the oxide semiconductor film. Can be done. Therefore, the oxide semiconductor film is made more pure and electrically made i-type (intrinsic).

Therefore, the transistor 4010 and the transistor 4 containing a highly purified oxide semiconductor film In 011, fluctuations in electrical characteristics are suppressed and it is electrically stable. Therefore, Fig. 3 to Fig. It is possible to provide a highly reliable semiconductor device as the semiconductor device of the present embodiment shown in 5. To.

Further, a transistor having a metal oxide film having an antistatic function is a backing of an oxide semiconductor film. It is possible to prevent the occurrence of parasitic channels on the channel side. In addition, to the transistor By preventing the generation of parasitic channels on the back channel side of the oxide semiconductor film, the threshold Fluctuations in value voltage can be suppressed.

Further, in the present embodiment, the acid of the transistor 4011 for the drive circuit is applied on the metal oxide film. A conductive layer may be provided at a position overlapping the channel forming region of the compound semiconductor film. Oxidizes the conductive layer By providing it at a position that overlaps the channel formation region of the semiconductor film, before and after the BT test The amount of change in the threshold voltage of the transistor 4011 can be further reduced. Also, The conductive layer may or may not have the same potential as the gate electrode of transistor 4011. Well, it can also function as a second gate electrode. Also, the potential of the conductive layer is GND, It may be 0V or in a floating state.

Further, the conductive layer shields the external electric field, that is, the external electric field is inside (thin film transistor). It also has a function (especially an electrostatic shielding function against static electricity) that does not act on the circuit part including To. Due to the shielding function of the conductive layer, the electricity of the transistor is affected by the influence of an external electric field such as static electricity. Characteristics can be prevented from fluctuating.

The transistor 4010 provided in the pixel unit 4002 is electrically connected to the display element to display the display panel. Make up the flannel. The display element is not particularly limited as long as it can display, and various display elements Can be used.

FIG. 3 shows an example of a liquid crystal display device using a liquid crystal element as a display element. In Fig. 3, the display element The child liquid crystal element 4013 includes a first electrode layer 4030, a second electrode layer 4031, and a liquid crystal. Includes layer 4008. An insulating film that functions as an alignment film so as to sandwich the liquid crystal layer 4008. 4032, an insulating film 4033 is provided. The second electrode layer 4031 is the second substrate 400. The first electrode layer 4030 and the second electrode layer 4031 are provided on the 6 side via the liquid crystal layer 4008. It is configured to be laminated.

The 4035 is a columnar spacer obtained by selectively etching the insulating film. It is provided to control the film thickness (cell gap) of the liquid crystal layer 4008. It should be noted that the spherical shape You may use a pacer.

When a liquid crystal element is used as the display element, a thermotropic liquid crystal, a low molecular weight liquid crystal, or a polymer liquid Crystals, polymer-dispersed liquid crystals, ferroelectric liquid crystals, antiferroelectric liquid crystals and the like can be used. these Depending on the conditions, the liquid crystal material of is cholesteric phase, smectic phase, cubic phase, kai. Indicates the larnematic phase, isotropic phase, etc.

Further, a liquid crystal showing a blue phase without using an alignment film may be used. The blue phase is one of the liquid crystal phases Yes, when the temperature of the cholesteric liquid crystal is raised, the direct transition from the cholesteric phase to the isotropic phase It is a previously expressed phase. The blue phase is expressed only in a narrow temperature range, which improves the temperature range. A liquid crystal composition mixed with 5% by weight or more of a chiral agent is used for the liquid crystal layer. A liquid crystal composition containing a liquid crystal exhibiting a blue phase and a chiral agent has a short response speed of 1 msec or less. In addition, since it is optically isotropic, no orientation treatment is required, and the viewing angle dependence is small. Also, the alignment film Since it is not necessary to provide a rubbing process, it is caused by the rubbing process. It is possible to prevent electrostatic damage caused by static electricity, and reduce defects and damage to the liquid crystal display device during the manufacturing process. Can be Therefore, it is possible to improve the productivity of the liquid crystal display device. Half oxide Transistors that use a conductor film have remarkable electrical characteristics due to the influence of static electricity. It may fluctuate and deviate from the design range. Therefore, a transistor using an oxide semiconductor film It is more effective to use a blue phase liquid crystal material for the liquid crystal display device having the above.

The intrinsic resistivity of the liquid crystal material is 1 x 10.⁹Ω · cm or more, preferably 1 × 10¹¹Ω · cm or more, more preferably 1 × 10¹²Ω cm or more. In addition, Honmei The value of resistivity in the detailed book shall be the value measured at 20 ° C.

The size of the holding capacity provided in the liquid crystal display device is the size of the transistor arranged in the pixel section. It is set so that the electric charge can be retained for a predetermined period in consideration of the current and the like. High-purity oxidation By using a transistor having a semiconductor film, the liquid crystal capacity of each pixel can be reduced. It is sufficient to provide a holding capacity having a capacity of 1/3 or less, preferably 1/5 or less. To.

The transistor using the highly purified oxide semiconductor film used in this embodiment is in the off state. The current value (off current value) in can be lowered. Therefore, electrical signals such as image signals The holding time can be lengthened, and the writing interval can be set longer when the power is on. Yo Therefore, the frequency of refresh operation can be reduced, which has the effect of suppressing power consumption. Play.

Further, the transistor using the highly purified oxide semiconductor film used in the present embodiment has a ratio. High-speed driving is possible because relatively high field-effect mobility can be obtained. Therefore, the liquid crystal display device By using the above-mentioned transistor in the pixel portion of the above, a high-quality image can be provided. Ma Further, the drive circuit portion having the transistor and the pixel portion can be formed on the same substrate. Therefore, the number of parts of the liquid crystal display device can be reduced.

The liquid crystal display device has TN (Twisted Nematic) mode and IPS (In-P). lane-Switching) mode, FFS (Fringe Field Swit) ching) mode, ASM (Axially Symmetric aligned Micro-cell mode, OCB (Optical Compensated B) irefringence) mode, FLC (Ferroelectric Liqui) d Crystal) mode, AFLC (Anti Ferroelectric Liq) uid Crystal) mode etc. can be used.

In addition, a normally black type liquid crystal display device, for example, a vertical orientation (VA) mode was adopted. It may be a transmissive liquid crystal display device. Here, the vertical orientation mode is the liquid crystal display panel liquid. It is a kind of method to control the arrangement of crystal molecules, and it is paired with the panel surface when no voltage is applied. This is a method in which the liquid crystal molecules are oriented in the vertical direction. There are several vertical orientation modes. However, for example, MVA (Multi-Domain Vertical Alignme) nt) mode, PVA (Patterned Vertical Alignment) Mode, ASV mode, etc. can be used. Also, some pixels Multi divided into regions (subpixels) and devised to defeat molecules in different directions A method called domainization or multi-domain design can be used.

Further, in a display device, a black matrix (light-shielding layer), a polarizing member, a retardation member, and reflection Optical members (optical substrates) such as preventive members are appropriately provided. For example, polarizing boards and retardation groups Circular polarization by a plate may be used. Also, use a backlight, side light, etc. as a light source. You may.

In addition, a time-divided display method uses multiple light emitting diodes (LEDs) as the backlight. It is also possible to perform (field sequential drive system). Field sequence By applying the char drive method, color display can be performed without using color filters. Can be done.

Further, as the display method in the pixel section, a progressive method, an interlaced method, or the like is used. be able to. In addition, as a color element controlled by pixels when displaying in color, RGB (R is It is not limited to the three colors (red, G stands for green, and B stands for blue). For example, RGBW (W stands for white) , Or RGB with one or more colors such as yellow, cyan, magenta, etc. added. In addition, it should be noted. The size of the display area may be different for each dot of the color element. However, this embodiment Is not limited to color display devices, but applies to monochrome display devices. You can also do it.

In addition, a luminescent element that uses electroluminescence as a display element included in the display device. Children can be applied. Light emitting elements that utilize electroluminescence are light emitting materials. Is distinguished by whether it is an organic compound or an inorganic compound, and in general, the former is organic E. The L element and the latter are called inorganic EL elements.

The organic EL element is an electron and a hole from a pair of electrodes by applying a voltage to the light emitting element. Is injected into each layer containing a luminescent organic compound, and an electric current flows. And those monsters The recombination of the rear (electrons and holes) causes the luminescent organic compound to form an excited state. Then, it emits light when its excited state returns to the ground state. From such a mechanism, like this A light emitting element is called a current excitation type light emitting element.

The inorganic EL element is divided into a dispersed inorganic EL element and a thin film type inorganic EL element depending on the element configuration. It is similar. The dispersed inorganic EL element has a light emitting layer in which particles of a light emitting material are dispersed in a binder. The luminescence mechanism utilizes donor and acceptor levels. Ccepter recombination type luminescence. In the thin film type inorganic EL element, the light emitting layer is sandwiched between the dielectric layers, and the light emitting layer is sandwiched between the dielectric layers. Furthermore, it has a structure in which it is sandwiched between electrodes, and the emission mechanism utilizes the inner-shell electronic transition of metal ions. Localized light emission to be used. Here, when an organic EL element is used as the light emitting element, explain about.

The light emitting element may have at least one of a pair of electrodes transparent in order to extract light. Soshi A transistor and a light emitting element are formed on the substrate, and light emission is taken out from the surface opposite to the substrate. Top surface injection, bottom surface injection that extracts light from the surface on the substrate side, and the surface on the substrate side and the surface opposite to the substrate There is a light emitting element with a double-sided injection structure that extracts light from the light, and any light emitting element with an injection structure can be applied. be able to.

FIG. 4 shows an example of a light emitting device using a light emitting element as a display element. Light emitting element 4 which is a display element The 513 is electrically connected to the transistor 4010 provided in the pixel unit 4002. The light emitting element 4513 is composed of the first electrode layer 4030, the electroluminescent layer 4511, and the second electric field. It is a laminated structure of polar layer 4031, but is not limited to the configuration shown. Taken from the light emitting element 4513 The configuration of the light emitting element 4513 can be appropriately changed according to the direction of the emitted light and the like.

The partition wall 4510 is formed by using an organic insulating material or an inorganic insulating material. Especially photosensitive resin Using the material, an opening is formed on the first electrode layer 4030, and the side wall of the opening is a continuous curve. It is preferable to form the inclined surface which is formed with a ratio.

The electroluminescent layer 4511 is configured such that a plurality of layers are laminated even if the electroluminescent layer 4511 is composed of a single layer. It doesn't matter whether it is done or not.

A second electrode layer to prevent oxygen, hydrogen, moisture, carbon dioxide, etc. from entering the light emitting element 4513. A protective film may be formed on the 4031 and the partition wall 4510. As a protective film, silicon nitride A film, a silicon nitride film, a DLC film, or the like can be formed. Also, the first substrate 400 Filler 45 in the space sealed by the first, second substrate 4006, and sealant 4005 14 is provided and sealed. It is highly airtight so that it will not be exposed to the outside air Protective film (bonded film, UV curable resin film, etc.) and cover material with less waste It is preferable to package (enclose) with.

The filler 4514 includes not only inert gases such as nitrogen and argon, but also UV curable resin. Can use thermosetting resin, PVC (polyvinyl chloride), acrylic, polyi Mid, epoxy resin, silicone resin, PVB (polyvinyl butyral) or EVA (d) (Tylene vinyl acetate) can be used. For example, use nitrogen as a filler. I.

If necessary, a polarizing plate or a circular polarizing plate (including an elliptical polarizing plate) is provided on the ejection surface of the light emitting element. Optical films such as retardation plates (λ / 4 plates, λ / 2 plates) and color filters may be provided as appropriate. I. Further, an antireflection film may be provided on the polarizing plate or the circular polarizing plate. For example, due to surface irregularities Anti-glare treatment that can diffuse the reflected light and reduce reflection can be applied.

It is also possible to provide electronic paper that drives electronic ink as a display device. To. Electronic paper is also called an electrophoresis display device (electrophoresis display), and is paper. It has the same readability as, low power consumption compared to other display devices, and can be made thinner and lighter. It has the advantage of.

The electrophoresis display device can be in various forms, but with the first particle having a positive charge. Multiple microcapsules in solvent or solute, including, with a second particle with a negative charge It is dispersed, and by applying an electric field to the microcapsules, microcapsules It is also possible to move the particles in the cell in opposite directions and display only the color of the particles gathered on one side. It is. The first particle or the second particle contains a dye and is transferred when there is no electric field. It doesn't work. Also, the color of the first particle and the color of the second particle are different (including colorless). ).

In this way, in the electrophoresis display device, a substance with a high dielectric constant moves to an electric field region with a high dielectric constant, so to speak. It is a display that utilizes the loose dielectrophoretic effect.

The microcapsules dispersed in a solvent are called electronic inks. Electronic ink can be printed on the surface of glass, plastic, cloth, paper, etc. Also Color display is also possible by using a color filter or particles having a dye.

The first particle and the second particle in the microcapsule are a conductor material, an insulator material, and the like. Semiconductor materials, magnetic materials, liquid crystal materials, ferroelectric materials, electroluminescent materials, electroluminescence Trochromic materials, a type of material selected from magnetic electrophoretic materials, or composite materials of these You can use it.

In addition, as electronic paper, a display device that uses a twist ball display method can also be applied. it can. The twist ball display method uses spherical particles painted in black and white for the display element. It is arranged between the first electrode layer and the second electrode layer, which are the existing electrode layers, and is arranged between the first electrode layer and the second electrode layer. This is a method of displaying by controlling the orientation of spherical particles by creating a potential difference in the electrode layer. To.

FIG. 5 shows an active matrix type electronic paper as a form of a semiconductor device. Figure 5 The electronic paper is an example of a display device using a twist ball display method.

Provided on the first electrode layer 4030 connected to the transistor 4010 and on the second substrate 4006. It has a black region 4615a and a white region 4615b between it and the second electrode layer 4031. Spherical particles 4613 containing a cavity 4612 filled with liquid around it The circumference of the spherical particles 4613 is filled with a filler 4614 such as resin. Second electrode Layer 4031 corresponds to a common electrode (opposite electrode). The second electrode layer 4031 is formed with a common potential line. It is electrically connected.

In addition, in FIGS. 3 to 5, the first substrate 4001 and the second substrate 4006 are made of glass. In addition to the substrate, a flexible substrate can also be used, for example, a translucent plastic. A substrate or the like can be used. As plastic, FRP (Fiberglas) s-Reinforced Plastics) board, PVF (polyvinyl fluoride) A film, a polyester film or an acrylic resin film can be used. Ma A sheet with a structure in which aluminum foil is sandwiched between PVF film and polyester film. Can also be used.

In addition, the metal oxide film 4020 generates parasitic channels on the back channel side of the oxide semiconductor film. By the process of removing impurities such as hydrogen, water, hydroxyl groups or hydrides, as well as preventing At the same time, it also has a function to supply oxygen, which is reduced from the oxide semiconductor film, to the oxide semiconductor film. To do.

As the metal oxide film 4020, a gallium oxide film formed by a sputtering method is used. Just do it. Further, a film obtained by adding indium or zinc to gallium oxide may be used, for example, a. A gallium oxide film containing 0.01 to 5 atomic% of ndium or zinc can be used. I By adding zinc or zinc, the electrical conductivity of the metal oxide film 4020 is improved. , The accumulation of electric charge can be further reduced.

Further, the insulating layer 4021 can be formed by using an inorganic insulating material or an organic insulating material. .. Acrylic resin, polyimide, benzocyclobutene resin, polyamide, epoxy tree When an organic insulating material having heat resistance such as fat is used, it is suitable as a flattening insulating film. Also In addition to the above organic insulating materials, low dielectric constant materials (low-k materials), siloxane-based resins, PSG (Phosphorus glass), BPSG (Phosphoron glass) and the like can be used. In addition, these An insulating layer may be formed by laminating a plurality of insulating films formed of the above materials.

The method for forming the insulating layer 4021 is not particularly limited, and depending on the material, a sputtering method or a method may be used. Pin coating method, dipping method, spray coating, droplet ejection method (injection method, screen) Printing, offset printing, etc.), roll coating, curtain coating, knife printing Arting and the like can be used.

The display device transmits light from a light source or a display element to perform display. Therefore, pixels that transmit light Thin films such as substrates, insulating films, and conductive films provided in the section are all for light in the visible light wavelength range. Translucent.

First electrode layer 4030 and second electrode layer 4031 (pixel electrode layer) that apply voltage to the display element , Common electrode layer, counter electrode layer, etc.), the direction of the light to be taken out and the electrode layer are provided. Translucency and reflectivity may be selected depending on the location and the pattern structure of the electrode layer.

The first electrode layer 4030 and the second electrode layer 4031 are indium acids containing tungsten oxide. Indium zinc oxide containing compound, tungsten oxide, indium oxidation containing titanium oxide Indium tin oxide containing titanium oxide, indium tin oxide (hereinafter referred to as ITO). ), Indium zinc oxide, indium tin oxide with silicon oxide added, etc. A conductive material can be used.

The first electrode layer 4030 and the second electrode layer 4031 are tungsten (W) and molybdenum. (Mo), Zirconium (Zr), Hafnium (Hf), Vanadium (V), Niobium (N) b), tantalum (Ta), chromium (Cr), cobalt (Co), nickel (Ni), chita Metals such as (Ti), platinum (Pt), aluminum (Al), copper (Cu), silver (Ag), Or it can be formed from one or more of its alloys or its nitrides. ..

Further, as the first electrode layer 4030 and the second electrode layer 4031, a conductive polymer (conductive poly) is used. It can be formed by using a conductive composition containing (also referred to as mer). As a conductive polymer Can use a so-called π-electron conjugated conductive polymer. For example, polyaniline Or its derivatives, polypyrrole or its derivatives, polythiophene or its derivatives, young Or a copolymer consisting of two or more kinds of aniline, pyrrole and thiophene, or an invitation thereof. Examples include conductors.

In addition, since transistors are easily destroyed by static electricity, etc., a protection circuit for protecting the drive circuit It is preferable to provide. The protection circuit is preferably configured by using a non-linear element.

By applying the transistor shown in the first or second embodiment as described above, various functions can be obtained. It is possible to provide a semiconductor device having the above.

(Embodiment 4) Information on the object is obtained using the transistor shown as an example in either 1 or 2 of the embodiment. A semiconductor device having a reading image sensor function can be manufactured.

FIG. 6A shows an example of a semiconductor device having an image sensor function. Figure 6 (A) shows It is an equivalent circuit of the sensor, and FIG. 6 (B) is a cross-sectional view showing a part of the photo sensor.

In the photodiode 602, one electrode is the photodiode reset signal line 658, and the other One electrode is electrically connected to the gate of transistor 640. Transistor 640 One of the source and drain is on the photosensor reference signal line 672, and the source or drain is The other is electrically connected to one of the source or drain of the transistor 656. To The Langista 656 has a gate on the gate signal line 659 and a source or drain on the other side. It is electrically connected to the sensor output signal line 671.

In the circuit diagram in this specification, it is clearly defined as a transistor using an oxide semiconductor film. As you can see, the symbol of the transistor using the oxide semiconductor film is written as "OS". There is. In FIG. 6 (A), the transistor 640 and the transistor 656 are oxide semiconductor films. It is a transistor using.

Figure 6 (B) shows the photodiode 602 and transistor 640 in the photosensor. It is a cross-sectional view shown and functions as a sensor on a substrate 601 (TFT substrate) having an insulating surface. A photodiode 602 and a transistor 640 are provided. Photo Daio A substrate 613 is provided on the transistor 640 using an adhesive layer 608. To.

On the transistor 640, a metal oxide film 631 having an antistatic function, an interlayer insulating layer 633, An interlayer insulating layer 634 is provided. The photodiode 602 is placed on the interlayer insulation layer 633. Provided on the electrode layer 641 provided on the interlayer insulating layer 633 and on the interlayer insulating layer 634. The first semiconductor layer 606a and the second half in order from the interlayer insulating layer 633 side between the electrode layer 642 and the electrode layer 642. It has a structure in which a conductor layer 606b and a third semiconductor layer 606c are laminated.

In the transistor 640, the oxide semiconductor film is subjected to heat treatment to generate hydrogen. Impurities such as water, hydroxyl groups or hydrides (also called hydrogen compounds) are defined from oxide semiconductor membranes. It is an oxide semiconductor film that has been graphically excluded and purified.

Further, the heat treatment was performed in a state where the oxide semiconductor film and the metal oxide film 631 containing oxygen were in contact with each other. Therefore, the main component material that constitutes the oxide semiconductor, which is reduced at the same time by the impurity removal process. Oxygen, which is one of the above, can be supplied to the oxide semiconductor film from the metal oxide film 631 containing oxygen. it can. Therefore, the oxide semiconductor film is made more pure and electrically made i-type (intrinsic).

Therefore, the transistor 640 containing the highly purified oxide semiconductor film has fluctuations in electrical characteristics. It is suppressed and electrically stable. Therefore, reliability as the semiconductor device of this embodiment It is possible to provide a high-quality semiconductor device.

The electrode layer 641 is electrically connected to the conductive layer 643 formed in the interlayer insulating layer 634, and is an electrode layer. The 642 is electrically connected to the gate electrode 645 via the electrode layer 644. Gate electrode 6 45 is electrically connected to the gate electrode of transistor 640 and is a photodiode 6 02 is electrically connected to the transistor 640.

Here, a semiconductor layer having a p-type conductive type as the first semiconductor layer 606a and a second semiconductor layer High resistance semiconductor layer (i-type semiconductor layer) as 606b, n-type as third semiconductor layer 606c An example is a pin-type photodiode in which semiconductor layers having a conductive type are laminated.

The first semiconductor layer 606a is a p-type semiconductor layer, and is an amorph containing an impurity element that imparts p-type. It can be formed by an ass silicon film. Group 13 for the formation of the first semiconductor layer 606a For plasma CVD method using semiconductor material gas containing impurity element (for example, boron (B)) Form more. Silane (SiH) as a semiconductor material gas₄) May be used. Or S i₂H₆, SiH₂Cl₂, SiHCl₃, SiCl₄, SiF₄Etc. may be used. Ma After forming an amorphous silicon film that does not contain impurity elements, diffusion method or ion implantation Impurity elements may be introduced into the amorphous silicon film by the method. For ion implantation, etc. It is preferable to diffuse the impurity element by heating or the like after introducing the impurity element. This As a method for forming an amorphous silicon film in the case of, LPCVD method, vapor deposition method, Alternatively, a sputtering method or the like may be used. The film thickness of the first semiconductor layer 606a is 10 nm or more 5 It is preferably formed so as to be 0 nm or less.

The second semiconductor layer 606b is an i-type semiconductor layer (intrinsic semiconductor layer) and is amorphous silicon. Formed by a membrane. A semiconductor material gas is used to form the second semiconductor layer 606b. A fast silicon film is formed by a plasma CVD method. As a semiconductor material gas, silane (SiH₄) May be used. Or Si₂H₆, SiH₂Cl₂, SiHCl₃, S iCl₄, SiF₄Etc. may be used. The formation of the second semiconductor layer 606b is performed by the LPCVD method, It may be carried out by a vapor phase growth method, a sputtering method or the like. The film thickness of the second semiconductor layer 606b is 2 It is preferably formed so as to be 00 nm or more and 1000 nm or less.

The third semiconductor layer 606c is an n-type semiconductor layer and contains an impurity element that imparts n-type. It is formed by a fast silicon film. Group 15 impurity sources are used to form the third semiconductor layer 606c. Formed by plasma CVD method using semiconductor material gas containing element (for example, phosphorus (P)) To. Silane (SiH) as a semiconductor material gas₄) May be used. Or Si₂H₆, SiH₂Cl₂, SiHCl₃, SiCl₄, SiF₄Etc. may be used. Also, impurities After forming an element-free amorphous silicon film, use the diffusion method or ion implantation method. Impurity elements may be introduced into the amorphous silicon film. Impurities by ion implantation method, etc. It is advisable to diffuse the impurity element by heating or the like after introducing the element. In this case As a method for forming a morphous silicon film, an LPCVD method, a vapor phase growth method, or a spatula method is used. The taling method or the like may be used. The film thickness of the third semiconductor layer 606c is 20 nm or more and 200 nm or more. It is preferable to form it so as to be on the bottom.

Further, the first semiconductor layer 606a, the second semiconductor layer 606b, and the third semiconductor layer 606c are a. It may be formed using a polycrystalline semiconductor instead of a morphus semiconductor, or a microcrystal (semi-ammo). Rufus (Semi Amorphous Semiconductor: SAS) Half It may be formed by using a conductor.

Microcrystalline semiconductors are metastable between amorphous and single crystals, considering the Gibbs free energy. It belongs to the state. That is, a semiconduct with a third state that is stable in free energy. It is a body, has short-range order, and has lattice distortion. Columnar or acicular crystals against the substrate surface It is growing in the normal direction. Microcrystalline silicon, which is a typical example of microcrystalline semiconductor, is Raman. 520 cm whose spectrum shows single crystal silicon^-1It is shifting to the lower wavenumber side. That is, 520 cm showing single crystal silicon^-1And 480 cm showing amorphous silicon^-¹There is a peak in the Raman spectrum of microcrystalline silicon between. Also, dangling bonds It contains at least 1 atomic% or more of hydrogen or halogen to terminate the. Furthermore, lattice distortion is caused by including rare gas elements such as helium, argon, krypton, and neon. By further promoting the above, stability is increased and a good microcrystalline semiconductor film can be obtained.

This microcrystalline semiconductor film uses a high-frequency plasma CVD method with a frequency of several tens of MHz to several hundreds of MHz. Or it can be formed by a microwave plasma CVD device with a frequency of 1 GHz or higher. .. Typically, SiH₄, Si₂H₆, SiH₂Cl₂, SiHCl₃, SiCl₄, S iF₄It can be formed by diluting a silicon-containing gas such as hydrogen with hydrogen. Also, in addition to hydrogen With one or more rare gas elements selected from helium, argon, krypton, neon A microcrystalline semiconductor film can be formed by diluting a silicon-containing gas. Including silicon at these times The flow rate ratio of hydrogen to gaseous is 5 times or more and 200 times or less, preferably 50 times or more and 150 times or more. Below, more preferably 100 times. Furthermore, in the silicon-containing gas, CH₄, C₂H₆etc Hydrocarbon gas, GeH₄, GeF₄Germanium-containing gas, F, etc.₂Even if you mix Good.

In addition, since the mobility of holes generated by the photoelectric effect is smaller than the mobility of electrons, it is a pin type. Photodiodes show characteristics that it is better to use the p-type semiconductor layer side as the light receiving surface. Here, p Photodiode 602 from the surface of the substrate 601 on which the in-type photodiode is formed An example of converting the light 622 received by the user into an electric signal is shown. Also, it is the opposite of the semiconductor layer side that is the light receiving surface. Since the light from the semiconductor layer side having the conductive type of is ambient light, what is the semiconductor layer side as the light receiving surface? It is preferable to use a conductive film having a light-shielding property for the electrode layer on the semiconductor layer side having the opposite conductive type. Also, The n-type semiconductor layer side can also be used as the light receiving surface.

As the metal oxide film 631, a gallium oxide film formed by a sputtering method is used. Just do it. Further, a film obtained by adding indium or zinc to gallium oxide may be used, for example, inn. A gallium oxide film containing 0.01 to 5 atomic% of gallium or zinc can be used. Inn By adding zinc or zinc, the electrical conductivity of the metal oxide film 631 is improved, and electricity is generated. Accumulation of load can be further reduced.

The interlayer insulating layers 633 and 634 function as a flattening insulating film in order to reduce surface irregularities. Insulation layer is preferable. Examples of the interlayer insulating layers 633 and 634 include polyimide and acrylic. Use organic insulating materials such as resin, benzocyclobutene resin, polyamide, and epoxy resin. Can be done. In addition to the above organic insulating materials, low dielectric constant materials (low-k materials) and siloxas Single layer or laminate of resin, PSG (phosphorus glass), BPSG (phosphorus glass), etc. Can be used.

As the interlayer insulating layer 633 and the interlayer insulating layer 634, an insulating material is used, depending on the material. , Sputtering method, spin coating method, dipping method, spray coating, droplet ejection method (a) Nkujet method, screen printing, offset printing, etc.), roll coating, curtains It can be formed by using a coating, a knife coating, or the like.

By detecting the light 622 incident on the photodiode 602, information on the object to be detected can be obtained. Can be read. When reading the information of the object to be detected, use a light source such as a backlight. Can be used.

As the transistor 640, the transistor shown as an example in the first or second embodiment is used. be able to. Impurities such as hydrogen, water, hydroxyl groups or hydrides (also called hydrides) A transistor containing an oxide semiconductor film that has been intentionally excluded from the oxide semiconductor film and has been purified. Is electrically stable because the fluctuation of the electrical characteristics of the transistor is suppressed. Also charged A transistor having a metal oxide film having a preventive function is a back channel of an oxide semiconductor film. It is possible to prevent the occurrence of parasitic channels on the side. In addition, oxides in transistors By preventing the generation of parasitic channels on the back channel side of the semiconductor film, the threshold voltage changes. Movement can be suppressed. Therefore, it is possible to provide a highly reliable semiconductor device.

This embodiment can be implemented in combination with the configurations described in other embodiments as appropriate. Is.

(Embodiment 5) The liquid crystal display device disclosed in this specification shall be applied to various electronic devices (including game machines). Can be done. Electronic devices include, for example, television devices (televisions or televisions). Receivers), monitors for computers, digital cameras, digital video cameras Cameras such as Mela, digital photo frames, mobile phones (also called mobile phones and mobile phone devices) C), portable game machines, mobile information terminals, sound playback devices, pachinko machines, and other large game machines. Which can be mentioned. Regarding the example of the electronic device including the liquid crystal display device described in the above embodiment. I will explain.

Figure 7 (A) shows an electronic book (also called an E-book), which has a housing 9630 and a display unit 9631. , Operation key 9632, solar cell 9633, charge / discharge control circuit 9634 can be .. The e-book shown in Fig. 7 (A) shows various information (still images, videos, text images, etc.). Function to show, function to display calendar, date or time on the display, display on the display Functions to manipulate or edit information, control processing by various software (programs) Can have such a function. Note that Fig. 7 (A) shows an example of the charge / discharge control circuit 9634. It has a battery 9635 and a DCDC converter (hereinafter abbreviated as converter) 9636. The configuration to be used is shown. Displaying the semiconductor device shown in any of the first to fourth embodiments. By applying it to Part 9631, it can be made into a highly reliable electronic book.

By adopting the configuration shown in Fig. 7 (A), the display unit 9631 can be a semi-transmissive type or a reflective type. When using a liquid crystal display device, it is expected to be used in relatively bright conditions, and the solar cell 9633 It is suitable because it can efficiently generate electricity and charge the battery 9635. The solar cell 9633 should be installed in the empty space (front or back) of the housing 9630 as appropriate. It is preferable because it can be configured to charge the battery 9635 efficiently. Suitable. If a lithium-ion battery is used as the battery 9635, the size can be reduced. There are advantages such as being able to plan.

The configuration and operation of the charge / discharge control circuit 9634 shown in Fig. 7 (A) are shown in Fig. 7 (B). A lock diagram will be shown and described. Figure 7 (B) shows the solar cell 9633, battery 9635, and For converter 9636, converter 9637, switches SW1 to SW3, display 9631 It shows about battery 9635, converter 9636, converter 9637, The switches SW1 to SW3 correspond to the charge / discharge control circuit 9634.

First, an example of operation when power is generated by the solar cell 9633 by external light will be described. The power generated by the solar cell 9633 will be the voltage to charge the battery 9635. The converter 9636 boosts or lowers the voltage. And the operation of the display unit 9631 is thick When the power from the positive battery 9633 is used, turn on the switch SW1 and convert 9 At 637, the voltage required for the display unit 9631 is boosted or stepped down. In addition, the display unit When not displaying on 9631, turn off SW1 and turn on SW2 to battery. The configuration may be such that the 9635 is charged.

Next, an example of operation when the solar cell 9633 does not generate electricity due to external light will be described. To. The power stored in the battery 9635 is converted by turning on the switch SW3. The data 9637 boosts or lowers the voltage. And, the operation of the display unit 9631 Power from Lee 9635 will be used.

The solar cell 9633 is shown as an example of charging means, but it can be backed up by other means. It may be configured to charge the terry 9635. Also, combine other charging means It may be configured.

Figure 8 (A) shows a notebook-type personal computer with a main body 3001 and a housing 3002. , Display unit 3003, keyboard 3004, etc. Embodiments 1 to High reliability by applying the semiconductor device shown in any of 4 to the display unit 3003. It can be a notebook personal computer.

Figure 8 (B) shows a personal digital assistant (PDA), which has a display unit 3023 on the main body 3021 and an outside. The interface 3025 and the operation buttons 3024 are provided. Also for operation There is a stylus 3022 as an accessory. The semiconductor shown in any of the first to fourth embodiments. A more reliable personal digital assistant (PDA) by applying the device to the display 3023. Can be.

FIG. 8C shows an example of an electronic book. For example, e-books have housing 2701 and It consists of two housings, the housing 2703. The housing 2701 and the housing 2703 have a shaft portion. It is integrated by 2711 and can be opened and closed with the shaft part 2711 as the axis. To. With such a configuration, it is possible to perform an operation like a paper book.

The display unit 2705 is incorporated in the housing 2701, and the display unit 2707 is assembled in the housing 2703. It is included. The display unit 2705 and the display unit 2707 are configured to display a continuous screen. It may be configured to display different screens. Configure to display different screens So, for example, the text is displayed on the display section on the right side (display section 2705 in Fig. 8 (C)), and the table on the left side. An image can be displayed on the display unit (display unit 2707 in FIG. 8C). Embodiment 1 No To apply the semiconductor device shown in any of 4 to the display unit 2705 and the display unit 2707. It can be a more reliable electronic book.

Further, FIG. 8C shows an example in which the housing 2701 is provided with an operation unit and the like. For example, the case Body 2701 equipped with power supply 2721, operation keys 2723, speaker 2725, etc. ing. The page can be sent by the operation key 2723. The same surface as the display of the housing It may be configured to include a keyboard, a pointing device, and the like. Also, the back of the housing External connection terminals (earphone terminal, USB terminal, etc.), recording medium insertion part, etc. on the surface or side It may be provided. Furthermore, the electronic book has a structure that has a function as an electronic dictionary. You may.

Further, the electronic book may be configured so that information can be transmitted and received wirelessly. By wireless, e-book It is also possible to purchase desired book data etc. from the server and download it. is there.

FIG. 8 (D) shows a mobile phone, which is composed of two housings, a housing 2800 and a housing 2801. ing. The housing 2801 includes a display panel 2802, a speaker 2803, and a microphone. 2804, pointing device 2806, camera lens 2807, external connection terminal 2 It is equipped with 808 and so on. In addition, the housing 2800 has a solar cell that charges mobile phones. It is equipped with 2810, external memory slot 2811, etc. In addition, the antenna is a housing 280 1 Built in inside. Display panel displaying the semiconductor device shown in any of the first to fourth embodiments. By applying it to Le 2802, it can be a highly reliable mobile phone.

In addition, the display panel 2802 is equipped with a touch panel, and the image is displayed in Fig. 8 (D). Multiple operation keys 2805 are shown by dotted lines. It is output by the solar cell 2810. A booster circuit is also mounted to boost the voltage required for each circuit.

The display direction of the display panel 2802 changes as appropriate according to the usage pattern. Also, the display panel Since the camera lens 2807 is provided on the same surface as the 2802, videophone calls are possible. To. Speaker 2803 and microphone 2804 are not limited to voice calls, but videophones, Recording and playback are possible. In addition, the housing 2800 and housing 2801 slide and show It can be changed from the unfolded state like 8 (D) to the overlapping state, which is suitable for carrying. It is possible to reduce the size.

External connection terminal 2808 can be connected to various cables such as AC adapter and USB cable It is possible to charge and communicate data with a personal computer or the like. Also external A recording medium can be inserted into the memory slot 2811 to support storage and movement of a larger amount of data. To.

In addition to the above functions, even if it has an infrared communication function, a TV reception function, etc. Good.

Fig. 8 (E) shows a digital video camera, which is the main body 3051, display unit (A) 3057, and contact. Eye part 3053, operation switch 3054, display part (B) 3055, battery 3056, etc. It is composed of. The semiconductor device shown in any one of the first to fourth embodiments is displayed on the display unit ( Highly reliable digital bidet by applying to A) 3057 and display (B) 3055 It can be an o-camera.

FIG. 8 (F) shows an example of a television device. The television device 9600 is a housing The display 9603 is built into the body 9601. The image is displayed by the display unit 9603. It is possible. Also, here, the stand 9605 supported the housing 9601. The configuration is shown. The semiconductor device shown in any one of the first to fourth embodiments is displayed on the display unit 9603. By applying to, it is possible to obtain a highly reliable television device.

The operation of the television device 9600 is performed by the operation switch provided in the housing 9601 and the separate remote control. It can be done by a control machine. Also, from the remote control controller to the remote controller A display unit for displaying the information to be output may be provided.

The television device 9600 is configured to include a receiver, a modem, and the like. To the receiver It can receive more general TV broadcasts, and can be wired or wireless via a modem. One-way (sender to recipient) or two-way by connecting to a communication network It is also possible to perform information communication (between the sender and the receiver, or between the recipients, etc.).

This embodiment can be implemented in combination with the configurations described in other embodiments as appropriate. Is.

400 board 401 Gate electrode 402 Gate insulating film 403 Oxide semiconductor film 405a source electrode 405b drain electrode 407 Metal oxide film 410 transistor 431 Metal oxide film 441 Oxide semiconductor film 601 board 602 photodiode 606a semiconductor layer 606b semiconductor layer 606c semiconductor layer 608 Adhesive layer 613 board 631 Metal oxide film 633 Interlayer insulation layer 634 Interlayer insulation layer 640 transistor 641 Electrode layer 642 Electrode layer 643 Conductive layer 644 Electrode layer 645 Gate electrode 656 transistor 658 Photodiode reset signal line 659 Gate signal line 671 Photo sensor output signal line 672 Photo sensor reference signal line 2701 chassis 2703 chassis 2705 Display 2707 Display 2711 Shaft 2721 power supply 2723 control key 2725 speaker 2800 housing 2801 housing 2802 display panel 2803 speaker 2804 Microphone 2805 Operation keys 2806 Pointing device 2807 Camera lens 2808 External connection terminal 2810 solar cell 2811 External memory slot 3001 body 3002 housing 3003 Display 3004 keyboard 3021 body 3022 stylus 3023 Display 3024 Operation buttons 3025 External interface 3051 body 3053 Eyepiece 3054 Operation switch 3055 Display (B) 3056 battery 3057 Display (A) 4001 board 4002 pixel part 4003 Signal line drive circuit 4004 Scan line drive circuit 4005 Sealing material 4006 board 4008 liquid crystal layer 4010 transistor 4011 Transistor 4013 Liquid crystal element 4015 Connection terminal electrode 4016 terminal electrode 4018 FPC 4018a FPC 4018b FPC 4019 Anisotropic conductive film 4020 Metal oxide film 4021 Insulation layer 4023 Insulation film 4030 Electrode layer 4031 Electrode layer 4032 Insulation film 4033 Insulation film 4510 bulkhead 4511 Electroluminescent layer 4513 Luminescent element 4514 Filler 4612 Cavity 4613 Spherical particles 4614 Filler 4615a Black area 4615b White area 9600 television equipment 9601 housing 9603 Display 9605 stand 9630 chassis 9631 Display 9632 Operation keys 9633 Solar cell 9634 Charge / discharge control circuit 9635 Battery 9636 converter 9637 converter