Bolometer and its manufacture

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Industrial application field]

The present invention generally relates to the manufacture of semiconductor devices, in particular to uncooled infrared detectors and methods thereof.

【0002】

[Conventional technology and problems]

Detection of infrared radiation emitted by warm objects is an important method for viewing (perceiving without visible light) at night. Infrared detectors are scanning or gaze arrays, cryogenic (formally the temperature of liquid nitrogen) or uncooled detectors, 3-5 micron or 8-12 micron spectral sensitivity range and photon or thermal detection mechanisms. It can be classified by various methods. Ultra-low temperature infrared detectors are typically made of semiconductors with a small bandgap (about 0.1-0.2eV), such as HgCdTe, and are photodiodes that absorb photons to generate electron-hole pairs. Operates as a photocapacitor. See, for example, US Pat. No. 4,686,373, which describes a hybrid device with an HgCdTe photocapacitor glued to a silicon signal processing circuit.

【0003】

Uncooled infrared detectors cannot use semiconductors with a small bandgap because the bandgap is only about 4 kT at room temperature and any signal is buried in the dark current. For this reason, uncooled infrared detectors rely on other physical phenomena and are less sensitive than cryogenic detectors, but do not require a cooling device or its energy consumption. For portable low-energy applications that do not require the higher detection capabilities of cryogenic detectors, it is preferable to choose an uncooled heat detector. At this time, it absorbs infrared photons and detects the resulting heating of the absorbing element. The thermal detector is usually one of three types: (1) pyroelectric detector, (2) thermocouple or (3) bolometer.

【0004】

Pyroelectric detectors operate at operating temperatures slightly below their Curie temperature (typically 0 ° C to 150 ° C) (BaSrTiO).₃Use a high electrical ceramic material (such as). A preferred strong electric material has a large change in spontaneous dielectric polarization at an operating temperature, and heats the strong electric body by sensing an induced voltage generated by generating an electric charge at both ends of the capacitor using the strong electric body as an insulator. Is detected. See, for example, U.S. Pat. Nos. 4,348,611, 4,142,207 and 4,379,232.

【0005】

Pyroelectric detectors are a hybrid system, with large detector arrays (such as an array of 256 x 256 pixels) due to defects in strong electrical materials, contact defects and raised joints. There is a problem when expanding, and the yield is low due to these defects.

【0006】

Thermocouples rely on changes in the contact potential of the junction of foreign conductors with temperature. For example, G. Rahiji et al., "Manufactured using integrated circuit technology," described in the 1980 IEEE IEDM Technical Digest 676, using bismuth antimony or polysilicon-gold pairs in monolithic arrays on silicon. See "Monolithic IEEE Detector".

【0007】

Bolometers formally rely on temperature changes in the resistance of a thin, thermally isolated metal or semiconductor coating. The thin film can be formed on a suspended dielectric film in a silicon substrate and can be placed adjacent to a monolithic detection circuit on the silicon substrate. By removing silicon from underneath the dielectric film by etching so that the dielectric film is suspended, the dielectric film is thermally isolated from the rest of the silicon substrate. Examples include 24 Infrared Physics 57 (1984) and 26 Infrared Physics 43 (1984), which include an amorphous silicon coating for temperature-related resistance changes and a butt nickel coating for infrared absorption and electrical contacts. 1986) Please refer to the paper by KC Rediyard. See here for the references listed above.

【0008】

Thermocouples and bolometers, along with detection circuits, can be monolithically built on silicon wafers, avoiding yield problems with pyroelectric detectors. However, thermocouples and bolometers have the problem of lower detection capability than pyroelectric detectors.

【0009】

Another bolometer scheme is described in US Pat. No. 5,021,663. In this scheme, current flows vertically through a detector with a relatively short resistance path, resulting in non-linear electrical characteristics and a voltage coefficient with a higher resistance value. Non-linear resistors reduce the performance of the detector array. Therefore, a cell having a large conductive passage is desirable. Therefore, improvements that solve any or all of these problems are now desired.

【0010】

[Means and actions to solve problems]

Other objectives and advantages will be apparent, some of which will be apparent from the description below, but are achieved by the present invention providing methods and devices for uncooled infrared detectors.

【0011】

Here, a bolometer for detecting radiation within a certain spectral range will be described. The bolometer includes an integrated circuit board and a pixel body separated from this board by at least one pillar. The pixel body is composed of an absorbing material, such as titanium, which absorbs radiation over a wide range, including, for example, a spectral range of 7 to 12 microns. The absorbent material heats the pixel body to a temperature proportional to the absorbed radiation. An insulating material is formed on top of the absorbent material. Further, on the insulating layer, a variable resistance material having an electric resistance corresponding to the temperature of the pixel body, for example, amorphous silicon is formed. A current flows through the variable resistance material substantially parallel to the integrated circuit board and is detected.

【0012】

The method of forming a bolometer cell involves forming a temporary layer on the substrate. A layer of absorbent material is formed on top of the interim layer, patterned and etched. An insulating layer is formed on top of the layer of absorbent material, patterned and etched. Then, a layer of variable resistance material is formed on the insulating layer. At least one pillar hole is formed in the layer of variable resistance material and the portion below it in the interim layer. Conductive pillars are formed in each pillar hole. The variable resistance material is patterned and etched to form a variable resistance depending on the temperature. Form at least two contacts, from pillars to temperature-variable resistors. Finally, the interim layer is removed.

【0013】

The advantage of the present invention is that it provides a productive infrared detection cell that can be manufactured at a reasonable cost compared to other currently available methods.

【0014】

Further, the cell of the present invention can be operated at a temperature close to room temperature, so that there is no need for a cryogenic device. As a result, the cost and dimensional constraints commonly associated with cryogenic devices are avoided.

【0015】

Further, since the current passage in the temperature sensing resistor is parallel to the substrate, not perpendicular to the inside of the resistor, a relatively long conductive passage is formed. Therefore, a more reasonable voltage coefficient of resistance can be achieved, and thus a more linear device can be made.

【0016】

The features described above of the present invention will be better understood from the following description of the drawings. Unless otherwise noted, the same numbers and symbols are used throughout the drawing for the corresponding parts.

【0017】

[Example]

Next, how to make and use the examples which are currently considered to be preferable will be described in detail. However, this invention provides a concept of invention with various applications, and this idea can be implemented in a wide variety of concrete forms. The examples specifically described here merely show specific examples of making and using the present invention, and do not limit the scope of the present invention.

【0018】

FIG. 1 is a schematic diagram showing an infrared image forming apparatus whose whole is indicated by 100. This device is an infrared lens device 102, an optional mechanical chopper 104 (this element is not required in the present invention), a bolometer array 106, a drive and readout circuit 108 for the array 106, a video processor 110, a display device 112. , And the timing and control circuit 114. The lens device 102 images the infrared radiation emitted from the warm object 116 onto the array 106. The chopper 104 may be a rotating disk having an opening that periodically blocks and passes infrared radiation collected by the lens device 102. In a preferred embodiment, the chopper 104 is of the in-focus / out-of-focus form. In one embodiment, the array 106 includes 65,536 bolometers arranged in 256 rows and 256 columns. Each bolometer corresponds to a pixel in the image of a warm object 116 plus the surrounding scene in the field of view of the lens device 102. The array 106 can either form a transparent window to infrared light on one side or be housed in a stainless steel vacuum chamber surrounded by the atmosphere of a gate with low heat transfer. Position the window so that radiation from the screen containing the warm object 116 passes through the window into array 106.

【0019】

The design gist of a microbolometer image sensor can be confirmed by considering each element in a series of events leading to the conversion of IR bundles into electrical signals. The first step is to convert the IR bundle into thermal energy stored in the pixels of the detector. To make this process as large as possible, the pixel absorption efficiency should be 100% over the IR band of interest. In order for the temperature rise of the pixel to be large, the heat capacity of the pixel must be minimized and the thermal isolation of the pixel from the surrounding structure must be maximized. In order to maximize the signal output of a pixel for a given temperature change, the drag coefficient of the bolometer resistor with respect to temperature should be as large as possible. The resistance value of the pixel must be compatible with the reading circuit and must control the power dissipation of the pixel in the reading state, which is required by the reading circuit. Finally, the electrical noise generated by both the pixel resistors and the read-ahead preamplifier must be small enough to provide the required image formation performance.

【0020】

As is often the case with engineering structures, many of these conditions are inconsistent with each other and not all parameters can be optimized individually. For example, trying to minimize the heat capacity of a pixel by making the detector thinner would probably make the absorption of the structure unacceptable and vice versa at the expense of heat capacity. It will maximize absorption.

【0021】

FIG. 2 wets a cross-sectional view of a first preferred embodiment of an engineeringly acceptable compromising structure between conflicting conditions . In this structure, the pixel body 120 is separated above the silin substrate 122 by pillars 124, and the substrate has a pixel preamplifier (not shown in the drawing) associated with a particular pixel. Pillar 124 can be made of aluminum, or any other material that meets structural and conductive requirements, such as other metals. Pillars 124 control the distance between the pixels 120 and the substrate mirror 126 formed by the infrared reflective coating deposited on the substrate 122. The reflective coating may be aluminum or any other suitable metal. The mirror 126 reflects the IR radiation that was not absorbed when it first passed through the pixel and returns it to the pixel, acting to be better absorbed. Ideally, the pixel body 120 should have λ / 4μ above the mirror 126 to obtain resonance performance (λ is the wavelength of the IR radiation to be detected, which is typically 7-12 microns). Can only be separated. However, in more practical cases, this interval is determined by processing or other interests. Experiments have shown that the IR absorption of this structure is not strongly dependent on the distance between the mirror and the absorber being about λ / 4, so this distance is usually chosen for ease of manufacture.

【0022】

The mirror 126 can also act as one of the pixel interconnects between the integrated circuit (IC) and the pixel resistor. The conductive pad 128 acts as another interconnect between the pixel and the IC. If the mirror 126 is not one of the pixel interconnects, another pad (not shown in the drawing) can be used. Note that mirror 126 may be omitted in the first pass if the IR absorption efficiency is high enough.

【0023】

The pixel body 120 is composed of successive layers of coating that perform various functions required for detection. The first coating layer 130 is an inactivating layer, which protects the main absorbent layer 132 from damage during the manufacturing process. Any coating with the required chemistry can be used. Examples of the coating include silicon dioxide, amorphous silicon and silicon nitride. The next layer, the absorbent layer 132, is a thin conductive layer that converts the incident IR into heat in the pixel by utilizing the absorption of free electrons. This absorbent layer is formally a metal such as titanium, nickel or chromium. Next, an insulating layer 134 is formed to isolate the absorber layer 132, followed by the next layer, which is the temperature sensing resistor coating 136 of the detector. The insulating coating 134 can also act as a secondary absorber of IR radiation. Any insulating coating can be used for the insulating layer 134, such as silicon dioxide, silicon nitride, or amorphous silicon. The layer 134 may be made of the same material as the inactivated layer 130. The final coating is the temperature sensitive resistor layer 136, which forms the bolometer resistor and can act as a secondary IR absorber. In a preferred embodiment, the bolometer resistor material 136 is 7 × 10.^-4It may be amorphous silicon doped in / Ω-cm. However, semiconductors or metalloids with an appropriate TCR (Temperature Coefficient of Resistance) can be used.

【0024】

An ideal bolometer has four properties: 1) large temperature dependence, 2) 100% IR absorption, 3) very small heat capacity, and 4) high thermal isolation. Therefore, the material chosen to form the device is chosen to optimize these properties. For example, the absorption layer 132 is chosen so that the maximum amount of IR energy is converted to heat. In practice, with a material such as titanium, 80-90% absorption was achieved.

【0025】

If the variable resistor is made of a suitable semiconductor, the spectral range can include visible light. Visible light is absorbed by the semiconductor and a carrier is generated within the bolometer resistor. This changes the resistance value of the detector.

【0026】

Once the IR energy is converted to heat, the temperature sensitive resistor material 136 must change the resistance value so that the heat, and thus the IR radiation, can be detected in the circuit below. In addition, the electrical noise generated within the resistor must be minimized. Formally, noise is 1 / F noise. 1 / F noise is typical of being generated by carrier gatrapped by defects in the coating. Preparing a low noise coating is now an empirical technique. Therefore, materials are selected that maximize thermal resistance dependence but minimize electrical noise. Some examples are amorphous silicon, germanium and metal oxides. However, other materials that meet this criterion may be used.

【0027】

The third property, the low heat capacity, is optimized by choosing a coating with appropriate physical strength so that each coating can be made very thin.

【0028】

The fourth property, good thermal isolation, is optimized by thermally isolating the pixels from the rest of the cell. This goal is achieved by separating the pixel body 120 from the substrate 122. Other thermal isolation schemes will be described later in FIG.

【0029】

A temperature sensing resistor 120 is connected to the pillar 124. This pillar is connected to the IC formed in the substrate 122 via the interconnection portion 138. The interconnect 138 can be made of any suitable conductive material.

【0030】

FIG. 3 shows a plan view of the pixel structure. Explaining FIG. 3 together with FIG. 2, the central portion of the pixel 120 absorbs IR radiation and becomes the main body of the pixel resistor. A support arm 142 along two sides of the pixel creates a long, thin, narrow thermal isolation resistor between the resistor body 120 and the spacer mirror 124 below it at the substrate-side end of the thermal resistor 142. .. The support arm is separated from the resistor body by a gap 146. In this way, the pixel body 140 is thermally isolated from the substrate 122.

【0031】

As shown in FIG. 3, there must be a trade-off between the thermal isolation of the pixel and the structural support of the pixel body. In the illustration, a gap 146 (which may be a gap) separates the support arm 142 from the pixel body 120 on three of the four sides. The gap 146 can be extended along the remaining two sides of the pixel body if further thermal isolation is desired. The mechanical strength of the support arm 142 is substantially reduced by this change. These trade-offs must also be considered for each individual design.

【0032】

A very thin coating of conductive material can be applied along the top surface of the support arm 142 to provide electrical contacts to the resistor body 120 at the center of the pixel. The coating should be as thin as possible so as not to sacrifice thermal isolation of the pixels.

【0033】

The metal piece 144 shown in FIG. 3 serves as a mechanical support and an electrical contact between the end of the support arm 142 and the top of the spacer mirror 124. The contact area shown in the figure is a device of the manufacturing method and does not directly contribute to this structure.

【0034】

An SEM (secondary electron microscope) photograph of the completed pixels is shown in Figure 4a. Figure 4b shows an array of mechanical pixels to demonstrate the manufacturing process for a tightly packed array.

【0035】

Individual pixels manufactured according to the cross-sectional view of FIG. 2 and having the shape of the plan view as shown in FIG. 3 were manufactured and operated as an IR detector using an external amplifier. The NEΔT (noise equivalent temperature difference) measured so far for these devices spans an IR passband of 7 to 12 microns and an electrical passband of 1 to 100 Hz, assuming an f / 1 optical system. When measured, it was as low as 0.18 ° C. The limiting factor in the performance of the device is the excessive noise (formally 1 / F noise) of the bolometer coating. This excess noise can in principle be reduced so that the performance of the device reaches 0.1-0.05 ° C or better.

【0036】

To currently implement these pixel designs, SiO is deposited to a thickness of approximately 250 Å by plasma CVD (Chemical Vapor Deposition).₂The absorbent material inactivating layer 130 of (silicon dioxide) is used. The absorbent layer 132 is composed of 140 Å of Ti (titanium) deposited on the inactivating layer 130. Insulator layer 134 is also SiO₂Formed by the plasma deposit of, the thickness varies between 1,000 and 2,000 Å. The resistance layer 136 is composed of a-Si (amorphous silicon) deposited by plasma CVD and is PF.₅(Phosphorus pentafluoride) Phosphorus extracted from the raw material is doped so as to have conductivity. The temperature coefficient of the resistance of this thin film currently deposited is 3 to 3.5%, and the conductivity is about 8 × 10.^-4cm^-1Ω^-1Is.

【0037】

We chose such a coating for the pixel structure, in part for the convenience of the process and for the important electrical and mechanical considerations. For example, the insulator coating can be silicon nitride, zinc sulfide or amorphous silicon instead of silicon dioxide. Table 1 summarizes some of these electrical and mechanical properties that are important.

【0038】

Next, the operation of one pixel will be briefly described. Infrared radiation enters the upper surface of the pixel body 120 and is absorbed by the absorption layer 132 to raise the temperature of the pixel. At this time, the resistance value of the temperature-sensitive resistance layer 136 changes in response to a temperature change, that is, in response to a change in the intensity of IR radiation. This change in resistance value can be monitored by an integrated circuit formed on the substrate 122.

【0039】

In the embodiment shown in FIG. 2, the current passes from the interconnection portion 138a through the resistance layer 136 in parallel with the substrate 122 and exits from the interconnection portion 138b downward. The conductive passage is considerably longer than in some conventional uses, as the current flows across the pixel in the lateral direction, as opposed to entering and exiting the pixel vertically. This difference is probably from 3,000 Å to 30 μ (two digits), but it brings a significant improvement in the voltage coefficient of the resistance value, thus resulting in a very linear resistance.

【0040】

The main process steps of the examples of the manufacturing method are shown in the cross section of Figure 5-10. First, FIG. 5 will be described by depositing an aluminum coating on the flattened surface of an IC designed for this application and patterning to reveal the electrical contacts 126,128 to the circuit. The polyimide (organic polymer) coating 150 is then deposited to a thickness of 2 μm by the usual rotary coating often used for this material. After this, the coating 150 is fired to ensure stability at high temperatures.

【0041】

Next, FIG. 6 will be described. The absorbent material inactivating film (currently SiO) is placed on the surface of the polyimide film 150.₂) Is formally applied by plasma CVD at a substrate temperature of 175 ° C. After the inactivating film 130, the Ti absorbent film 132 is deposited by DC magnetron sputtering. After this deposit, the Ti coating 132 is BCl as shown in FIG.₃By plasma etching in a mixture of (boron trichloride) and other gases, the pattern is squeezed into the shape of the body of a pixel resistor without a support arm.

【0042】

Then, using plasma CVD, SiO₂Insulator coating 134 is applied to a thickness of 1000-2,000 Å. This coating and the underlying inactivating coating, which is now shown as layer 135 in Figure 7-10, is CF.₄(Carbon tetrafluoride) and O₂(Oxygen) or other known SiO₂Using an etchant, pattern and plasma etch at once. This pattern includes both the pixel center body and the support arm.

【0043】

Next, FIG. 8 will be described. On top of this patterned insulating layer, SiH as a raw material₄(Silane) and PF₅A a-Si (amorphous silicon) coating 136 doped in n-type or p-type is deposited by plasma CVD using (phosphorus pentafluoride, but boron trifluoride may be used). The parameters of this deposit are chosen to obtain the desired electrical and physical properties. Next, with reference to FIG. 9, the a-Si coating 136 is selectively removed where it is necessary to expose the underlying polyimide coating 150 at the pillar location. A plasma of oxygen and argon is then used to remove this polyimide until it reaches the metal contacts 126 or 128 beneath the IC formed within the substrate 122. The patterned a-Si coating 136 is used as an etch mask during this etching process. The temperature-sensitive a-Si coating 136 is repatterned, this time at the contours of both the pixel body and the support arm, using photoresist treatment and plasma etching in carbon tetrafluoride and oxygen.

【0044】

The structure is then recoated with a negative photoresist of the pillar pattern (not shown) and the aluminum pillars 124 are deposited by vacuum metallizing until the thickness of the polyimide coating is 2.0 microns. An excess metal is then stripped from this structure using a specially developed lift-off method, leaving pillars 124 in the holes within the polyimide coating 150 to nest and contact the IC.

【0045】

The electrical boundaries of the resistor body are then limited by a thin (100 Å or less) coating of the conductor that is deposited and patterned as shown in FIG. This coating acts as a contact with a small resistance value to the resistance body at the center of the pixel.

【0046】

Next, with reference to FIG. 10, metallizing of the last element of the structure, the metal piece, is applied using two layers of photoresist. The first layer 152 fills the void between the edge of the polyimide 150 and the body of the pillar 124, and the second layer 154 limits the body of the metal piece pattern. The metal of the metal pieces 138 is deposited on these photoresist coatings and excess metal is removed by conventional lift-off methods. This completes the structure shown in FIG. 2, except for removing the underlying polyimide film 150.

【0047】

Since freely upright pixels can be damaged by immersion in chemicals, the substrate wafers are sawed into individual arrays, the wafers cleaned by conventional chemical means, and then under the pixels. Remove the polyimide film from. After sawing and cleaning after sawing, oxygen and argon plasma are used to remove the underlying polyimide coating from underneath the pixels by etching. The typical etching time is now about 3-5 hours using a substrate temperature of 150 ° C.

【0048】

The structural parameters just described can be further optimized. In addition, the placement of the coating within this structure can be modified to simplify the manufacturing procedure or to improve performance. For example, if this structure is inverted, the pixel body can be limited by one pattern trimming step, and the matching of the insulator coating and the resistance coating can be guaranteed.

【0049】

Although the present invention has been described for the illustrated examples, this description should not be construed as limiting the invention. From the above description, those skilled in the art can easily consider various modifications of the illustrated embodiments and other embodiments of the present invention. Therefore, please be aware that the scope of claims includes such changes or other examples.

【0050】

[table 1]

<img file="JPP3386830B2_D0001.tif" />In connection with the above description, the present invention has the following embodiments.

【0051】

(1) In a bolometer that detects radiation within a certain spectrum range, the bolometer has an integrated circuit board and a pixel body separated from the board by at least one pillar, and the pixel body is within the spectrum range. It has an absorbing material that absorbs radiation and heats the pixel body to a certain temperature in proportion to the absorbed radiation, an insulating material formed on the absorbing material, and an electric resistance corresponding to the temperature of the pixel body. A bolometer composed of a variable resistance material, in which a current flows through the variable resistance material substantially in parallel with the integrated circuit board, and the variable resistance material is formed on the insulating layer.

【0052】

(2) In the bolometer described in item (1), a bolometer having a spectral range of 7 to 12 microns.

【0053】

(3) In the bolometer described in item (1), the bolometer in which the pixel body is about 2 to 3 microns away from the integrated circuit board.

【0054】

(4) In the bolometer described in item (1), a bolometer in which an inactivating layer is formed under the absorbent material.

【0055】

(5) In the bolometer described in item (1), the bolometer whose absorbent material is titanium.

【0056】

(6) In the bolometer described in item (1), the bolometer in which the variable resistance material is amorphous silicon.

【0057】

(7) In the bolometer described in paragraph (1), the bolometer detects radiation in another second spectral range of the spectral range.

【0058】

(8) In the bolometer described in paragraph (7), a bolometer in which the second spectral range is visible light.

【0059】

(9) In the method of forming a bolometer cell on a semiconductor substrate, a temporary layer is formed on the substrate, a layer of an absorbent material is formed on the temporary layer, and the layer of the absorbent material is formed. The insulating layer is formed on the layer of the absorbing material by patterning and etching, the insulating layer is patterned and etched, and the layer of the variable resistance material is formed on the insulating layer, and the variable resistance material is formed. At least one pillar hole is patterned and etched in the layer and the portion below the provisional layer, and the variable resistance material is patterned and etched to form a temperature variable resistance. A method comprising forming a pillar in each of one pillar hole, forming at least two contacts from at least two pillars to a temperature variable resistor, and removing the provisional layer.

【0060】

(10) In the method described in paragraph (9), a method including a step of depositing a mirror material on a substrate before forming a temporary layer.

【0061】

(11) In the method described in paragraph (10), the method in which the mirror material is aluminum.

【0062】

(12) In the method described in paragraph (9), the method in which the provisional layer is polyimide.

【0063】

(13) In the method according to (9), a method including a step of sawing the substrate at least partially before removing the temporary layer.

【0064】

(14) In the method according to (9), a method including a step of forming an inactivating layer before forming a layer of an absorbent material.

【0065】

(15) In the method described in paragraph (9), a method in which the step of forming a layer of an absorbent material includes depositing a metal.

【0066】

(16) In the method described in paragraph (9), a method in which the step of forming a layer of a variable resistance material includes depositing amorphous silicon.

【0067】

(17) In the method described in paragraph (14), about 10 amorphous silicons are used.^-6Ω^-1cm^-2~ 10^-2Ω^-1cm^-2How it is doped into.

【0068】

(18) Consists of an array of bolometers, each bolometer consisting of an integrated circuit board and a pixel body separated by at least one pillar from the board, the pixel body being within the selected spectral range. An absorbing material that absorbs radiation and heats the pixel body to a temperature proportional to the absorbed radiation, an insulating material formed on the absorbing material, and a variable resistance material that has electrical resistance corresponding to the temperature of the pixel body. A current flows through the variable resistance material substantially parallel to the integrated circuit board, the variable resistance material is formed on the insulating layer, and a change in resistance of the variable resistance material is detected. An infrared detection array in which a circuit to be used is formed on the substrate.

【0069】

(19) In the array described in paragraph (18), an array having a spectral range of about 7 to 12 microns.

【0070】

(20) In the array described in paragraph (18), the array in which the absorbent material is titanium.

【0071】

(21) In the array described in paragraph (18), the array in which the variable resistance material is amorphous silicon.

【0072】

(22) In the array described in paragraph (18), an array in which each bolometer detects radiation in a second spectral range in addition to the above spectral range.

【0073】

(23) In the array described in paragraph (22), the array in which the second spectral range is visible light. (24) A bolometer that detects radiation within a certain spectral range has been described. The bolometer includes an integrated circuit board 122 and at least one pillar 124, a pixel body 120 separated from the board 122. The pixel body 120 may be, for example, 7 to 12 microns, but is composed of an absorbing material 132, such as titanium, that absorbs radiation within this spectral range. The absorber 132 heats the pixel body 120 to a temperature proportional to the absorbed radiation. The insulating material 134 is formed on the absorbent material 132. Further, for example, amorphous silicon is considered, and a variable resistance material 136 having an electric resistance corresponding to the temperature of the pixel body 120 is formed on the insulating layer 134. A current flows through the variable resistor material 136 substantially parallel to the integrated circuit board 122 and is detected. Other devices and methods have also been described.

[Simple explanation of drawings]

[Figure 1]

FIG. 6 is a block diagram of an infrared detector including a bolometer array of the first preferred embodiment.

[Figure 2]

Sectional drawing of the bolometer cell of a preferred embodiment.

[Fig. 3]

Top view of the bolometer cell of the preferred embodiment.

[Fig. 4]

Micrograph of infrared detector.

[Fig. 5]

Sectional view to help you understand the manufacturing process of an example.

[Fig. 6]

Sectional view to help you understand the manufacturing process of an example.

[Fig. 7]

Sectional view to help you understand the manufacturing process of an example.

[Fig. 8]

Sectional view to help you understand the manufacturing process of an example.

[Fig. 9]

Sectional view to help you understand the manufacturing process of an example.

[Fig. 10]

Sectional view to help you understand the manufacturing process of an example.

[Explanation of symbols]

120 pixel body 122 Integrated circuit board 124 pillar 132 Absorbent material 134 Insulation material 136 Variable resistance material