Semiconductor device and circuit board for mounting semiconductor element

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention belongs to the technical field of connecting a semiconductor element in a bare chip state to a circuit board, and relates to a new semiconductor device and a circuit board for improving the mountability thereof.

【0002】

[Conventional technology]

A large number of semiconductor elements such as ICs are usually formed on a wafer, then divided into individual chips and connected to a circuit board for use. With the further large-scale integration of ICs, the number of electrodes formed on one chip has increased, and the shape and arrangement pattern of the electrodes have become finer and narrower in pitch. In terms of mounting technology, a method of connecting the chip and the circuit board by making the conductor portion of the circuit board correspond to the electrode position of the chip without using a method of bridging the connection between the chip and the circuit board (for example, a flip chip). Bonding) has come to be used. Further, in relation to the connection method, bare chip mounting is performed in which the chip is mounted on a substrate in a bare state.

【0003】

As described above, one of the connection methods for connecting the electrode of the chip and the conductor portion of the circuit board in correspondence with each other is a method of interposing an anisotropic conductive film between the chip and the circuit board. Be done.

【0004】

The anisotropic conductive film is a film that exhibits anisotropy in terms of conductivity, exhibits conductivity in the direction of penetrating the front and back surfaces of the film, but exhibits insulating properties in the direction in which the surface of the film expands. ..

【0005】

[Problems to be Solved by the Invention]

To mount the chip via the anisotropic conductive film, the chip, the anisotropic conductive film, and the circuit board are overlapped, aligned with each other, and then the chip and the anisotropic conductive film are bonded. The anisotropic conductive film and the circuit board must be joined at once. However, there is a problem that advanced alignment technology is required to align the three parties at once, a simple chip mounting device cannot be used as it is, and the productivity in the mounting process is low.

【0006】

An object of the present invention is to solve the above problems and further improve the productivity in the mounting process when the semiconductor element and the circuit board are connected via an anisotropic conductive film.

【0007】

[Means for solving problems]

The above problem is solved by the following aspects. (1) An anisotropic conductive film having a structure in which a plurality of conduction paths are provided in a film substrate made of an insulating resin with metal conductors insulated from each other and penetrating the film substrate in the thickness direction. However, it is characterized in that it is bonded to the electrode surface of the semiconductor element, and each electrode of the semiconductor element is in a state where it can be electrically connected to the outside through a conduction path in the anisotropic conductive film. Semiconductor device.

【0008】

(2) An anisotropic conductive film having a structure in which a plurality of conduction paths are provided in a film substrate made of an insulating resin with metal conductors insulated from each other and penetrating the film substrate in the thickness direction. Is bonded to all the electrode surfaces of the plurality of semiconductor elements formed on the wafer, and each electrode of the semiconductor element can be electrically connected to the outside through a conduction path in the anisotropic conductive film. A semiconductor device characterized by being in a state.

【0009】

(3) The electrode of the semiconductor element and the end of the conduction path of the anisotropic conductive film are in a state of contact or bonding, and the materials of both are in the state of contact or bonding. The semiconductor device according to (1) or (2) above, wherein the combination is a combination in which the electrode side is aluminum and the conduction path side is gold, or a combination in which the electrode side is barrier metal and the conduction path side is solder.

【0010】

(4) An idiosyncratic conductive film having a structure in which a plurality of conduction paths are provided in a film substrate made of an insulating resin in a state where metal conductors are insulated from each other and penetrate the film substrate in the thickness direction. However, the mounting circuit formed as a conductor pattern corresponding to the electrodes of the semiconductor element is joined to the mounting circuit side surface of the circuit board having the mounting circuit formed on one surface of the insulating substrate, and the mounting circuit of the circuit board is formed. A circuit board for mounting a semiconductor element, which is characterized in that it can be electrically connected to a semiconductor element via an anisotropic conductive film.

【0011】

(5) The mounting circuit of the circuit board and the end of the conduction path of the anisotropic conductive film are in contact or bonded state, and the materials of both are in the contacted or bonded state. The circuit board for mounting a semiconductor element according to (4) above, wherein the combination is a combination in which the mounting circuit side is solder and the conduction path side is gold.

【0012】

BEST MODE FOR CARRYING OUT THE INVENTION

First, the semiconductor device according to the above-mentioned aspects (1) and (2) will be described. As shown in FIG. 1, the semiconductor device according to the above aspect (1) according to the present invention has a surface on the electrode 11 side of the semiconductor element 1 in a bare chip state (a state of a bare chip including a passivation film), which will be described later. The conductive film 2 is integrally bonded to form a single chip. Each electrode 11 of the semiconductor element 1 (11a and 11b appear in the figure) is connected to the end of the conduction path 21 of the anisotropic conductive film 2 in a contacted or bonded state. For example, in FIG. 1, the electrodes 11b correspond to the conduction paths 21a and 21b, and are in a contacted or joined state. As a result, the semiconductor element 1 in the bare chip state becomes one semiconductor device that can be electrically connected to the outside (particularly the circuit board) via the anisotropic conductive film 2, and the chip immediately after being divided. It can be treated in exactly the same way as.

【0013】

With this configuration, the mounting device such as a flip chip bonder can be used as it is, which improves the productivity in the mounting process and efficiently obtains a three-way connection of a chip, an anisotropic conductive film, and a circuit board. Will be able to. Further, since the anisotropic conductive film used is a structure composed of a metal lead wire and an insulating resin and has an appropriate elastic modulus as described later, it can be connected to the outside with high connection reliability. Chip.

【0014】

The bare-chip state semiconductor element, which is one of the components of the semiconductor device of the present invention, may be mounted on a circuit board via an anisotropic conductive film, but is sporadic like one light emitting element. The usefulness of the present invention becomes more remarkable in an element in which a large number of electrodes are arranged at a narrow pitch, such as a CPU, a memory, and a processor in which various arithmetic circuits are integrated.

【0015】

Further, the semiconductor device according to the present invention includes not only one in which elements are individually divided, but also one in which a plurality of semiconductor elements are formed on a wafer and one anisotropic conductive film is bonded to the wafer. Such a semiconductor device may be regarded as an intermediate before division, or may be regarded as a device capable of being connected to the outside regardless of whether or not the semiconductor device is divided. Such a semiconductor device is the aspect (2) above.

【0016】

The circuit board of the other party on which the semiconductor device of the present invention should be mounted may have a conductor portion such as a flexible substrate or a rigid substrate on which the semiconductor device can be mounted. The structure of the circuit board has at least a conductor pattern corresponding to the electrode pattern of the element on one surface of the insulating substrate so that a semiconductor element in a bare chip state can be mounted, and is formed inside the substrate or on the other surface. Some are connected to the circuit, and some have lead contacts, bump contacts, and the like.

【0017】

The anisotropic conductive film, which is one of the components of the semiconductor device of the present invention, has a plurality of metal conductors as conduction paths 21 in the film substrate 22 made of an insulating resin, as shown in FIG. 2 as a single item. It has a provided structure. The conduction paths are insulated from each other and penetrate the film substrate 22 in the thickness direction.

【0018】

Further, as shown in FIGS. 3 and 4 with respect to the aspect of FIG. 2, a layer 23 made of another material may be provided between the resin material of the film substrate 22 and the conduction path 21. Such layers may be provided in multiple layers, and the material may be selected according to the application and required characteristics such as insulation and conductivity. For example, in FIG. 3, a resin material having high adhesiveness is used as a resin material constituting the film substrate 22, and a material having high heat-resistant insulation is used for the layer 23 surrounding the conduction path 21.

【0019】

Examples of the insulating resin constituting the film substrate include thermosetting resins and thermoplastic resins. For example, thermoplastic polyimide resin, epoxy resin, polyetherimide resin, polyamide resin, phenoxy resin, acrylic resin, polycarbodiimide resin, fluorine resin, polyester resin, polyurethane resin, polyamideimide resin and the like can be mentioned as appropriate according to the purpose. Be selected. These resins may be used alone or in combination.

【0020】

The thickness of the film substrate is preferably about 10 μm to 200 μm, particularly preferably about 25 μm to 150 μm from the viewpoint of reliability and thinning.

【0021】

The material of the metal conducting wire constituting the conduction path is preferably copper, gold, aluminum, nickel or the like, and particularly preferably copper or gold from the viewpoint of conductivity. Among the metal conductors, those manufactured to conduct electricity, such as the copper wire specified in JIS C 3103, are more preferable, and they are the most excellent in terms of electrical characteristics, mechanical characteristics, and cost. It becomes a conduction path.

【0022】

The shape, size, and number of the cross section of the conduction path (cut perpendicular to the passage direction) can be appropriately selected according to the electrodes of the chip, but corresponds to a fine pitch electrode arrangement pattern such as a pitch of 50 μm or less. The outer diameter is preferably 5 to 30 μm. As long as the above conditions are satisfied, the cross-sectional shape of the conduction path may be any shape such as a circle or a polygon. It is preferable that one electrode of the chip corresponds to a plurality of conduction paths of about 1 to 3.

【0023】

The end of the conduction path with respect to the surface of the film substrate may be protruding, recessed, or the same surface as the film surface, and these states may be mixed. Further, the conduction path may be projected on one surface of the film substrate and recessed on the other surface, and the combination is free. The mode of the unevenness at the end of the conduction path may be selected according to the electrode of the chip to be joined and according to the circuit board of the mounting partner. Normally, the electrodes of the chip and the conductor portion of the circuit board to be mounted are often pads that have a minute concave shape. Therefore, as shown in FIG. 2 (b), conduction paths are projected on both surfaces of the film substrate. Is preferred for reliable connections.

【0024】

The amount of protrusion when the end of the conduction path is projected from the film surface is preferably about 0.01 μm to 5 μm, particularly preferably about 0.1 μm to 2 μm from the viewpoint of connection reliability. The method of projecting the end of the conduction path from the surface of the film substrate is as described later.

【0025】

The surface of the end of the conduction path may be further coated with a metal material having high conductivity or a material such as gold or nickel having excellent corrosion resistance. Further, as the material of the conduction path, particularly the material for covering the end portion on the semiconductor element side, a preferable material may be selected depending on the material of the surface of the electrode of the semiconductor element. For example, a combination of aluminum (electrode side) and gold (conduction path side), barrier metal (electrode side) and solder (conduction path side) can be mentioned. The barrier metal is a metal used to form a layer for preventing a diffusion reaction between Al used as a wiring material in an element and an external metal, and examples thereof include simple substances such as Cr, Au and Ni, and alloys. Be done.

【0026】

The conduction paths should be more closely arranged within the film substrate. The pattern of the arrangement of the conduction paths when the film surface is viewed may be a close-packed state as shown in FIG. 2 (a), a square matrix as shown in FIG. 4, or a random dense state. , The close-packed state is preferable for dealing with fine electrodes.

【0027】

In order to obtain a structure in which a large number of metal conducting wires penetrate a film substrate as a conduction path, a large number of insulated wires are tightly bundled and fixed so as not to be separated from each other, and a surface angled with each insulating electrode is cut. Examples thereof include a method of slicing to a desired film thickness. Among them, the most preferable method for producing the anisotropic conductive film of the present invention is a production method having the following steps or steps.

【0028】

A process in which one or more coating layers made of an insulating resin are formed on the surface of a metal lead wire having a diameter of a conduction path (for example, 10 to 50 μm) to form an insulating lead wire, and this is wound around a core material. A step of heating and / or pressurizing the coil obtained by the winding, and fusing and / or crimping the coating layers of the wound insulating wires to each other to form a coil block. A step of cutting the coil block obtained in the above step into a predetermined film thickness with a plane intersecting the wound insulating lead wire at an angle as a cross section. A step of etching a portion of the insulating resin of the film-like material obtained above to project a metal lead wire from the film surface. A step of further depositing metal on the end surface of the metal lead wire exposed on the film surface of the film-like material obtained above, and projecting the metal from the film surface.

【0029】

The above steps are a method in which the insulated wires can be bundled most efficiently and densely, and the closest assembly pattern of the conduction path as shown in FIG. 2 (a) can be easily obtained. After the above steps, the above or the above steps may be selected and added by a method of projecting a conduction path.

【0030】

According to the above manufacturing method, the coating layer formed on the surface of the metal lead wire finally becomes a film substrate. When forming a coating layer on the surface of a metal lead wire, it is possible to form a multi-layered material according to various characteristics such as for insulation and for adhesion. Therefore, in the obtained anisotropic conductive film, various electrical and mechanical properties such as conductivity, dielectric, insulating property, adhesiveness, and strength change in the direction in which the film surface expands. .. For each step of ~ in the above manufacturing method, the technique described in WO98 / 07216 Isotropically conductive film and its manufacturing method may be referred to.

【0031】

When bonding a semiconductor element and an anisotropic conductive film, the conduction path corresponding to the electrode of the semiconductor element must be connected (contact, bonded, etc.) to the electrode with high reliability. For that purpose, the entire anisotropic conductive film needs to have appropriate elasticity. The elastic modulus of the isotropically conductive film as a whole has anisotropy as well as conductivity, and is different in the film thickness direction and the film surface direction. In the present invention, the preferred elastic modulus of the anisotropic conductive film as a whole is defined with respect to the film surface direction, and the temperature range is set to 0.1 to 5 GPa in the temperature range of 25 ° C to 125 ° C. It is preferable from the viewpoint of connection reliability later.

【0032】

Factors that determine the elastic modulus of the entire structure of the anisotropic conductive film include the material of the conduction path, the cross-sectional shape and total length of the conduction path, the density and arrangement pattern of the arrangement of the conduction path, the material of the film substrate, and the film substrate. Such as thickness. These elements may be selected and set within the above elastic modulus range.

【0033】

The connection state between the electrode and the conduction path may be a bonding state due to welding of metals or a state in which they are only in contact with each other, and is selected according to the bonding between the semiconductor element and the anisotropic conductive film. do it. For bonding a semiconductor element and an anisotropic conductive film, a film substrate material having adhesiveness is used, and the adhesiveness is used for bonding (the electrode and the conduction path may be only in contact), or the electrode and the conduction path may be bonded. Examples thereof include bonding in which the film substrate is welded and the bonding force is used, and bonding in which an adhesive is used as the material of the film substrate and the electrode and the conduction path are welded.

【0034】

An adhesive material is a material that exhibits adhesiveness as it is or is pressurized, or that does not exhibit adhesiveness as it is but is adhered by heating (may be accompanied by pressure). A material that can be used. Examples of the latter material include thermoplastic resins and thermosetting resins.

【0035】

When joining a semiconductor element and an anisotropic conductive film, a manufacturing method may be used in which the anisotropic conductive films having a size corresponding to the element are joined one by one, but a plurality of states formed on the wafer may be used. A piece of anisotropic conductive film having a size including those semiconductor elements (for example, the same size as a wafer) is bonded to the semiconductor elements of the above, and the electrodes of each element are connected to the conduction path corresponding to them. The manufacturing method of dividing the semiconductor element into individual chips together with the anisotropic conductive film after confirming the above method provides the most productive and highly reliable bonding. Further, as described above, when the device in the state before division at that time is regarded as one independent device, it is the device of the above-mentioned aspect (2).

【0036】

Next, a circuit board for mounting a semiconductor element (hereinafter, also referred to as a mounting board) according to the aspects (4) and (5) above will be described. As shown in FIG. 5, the mounting substrate of the present invention is a circuit board 3 to which an anisotropic conductive film 2 is bonded. The circuit board 3 has a mounting circuit 31 formed on one surface of the insulating board 32, and the mounting circuit 31 is formed as a conductor pattern corresponding to an electrode of a semiconductor element in a bare chip state. is there. The end of the conduction path 21 of the anisotropic conductive film 2 is in contact with or joined to the circuit board 3, so that the chip can be mounted on the circuit board 3 via the anisotropic conductive film 2. It has become.

【0037】

With this configuration, as in the case of the above aspect (1), the mounting device such as the flip chip bonder can be used as it is, so that the productivity in the mounting process is improved, and the chip, the anisotropic conductive film, and the circuit board are used. However, it will be possible to efficiently obtain a three-way connection. Further, as in the case of the above-mentioned aspect (1), the feature of the anisotropic conductive film makes the substrate capable of mounting the chip with high connection reliability.

【0038】

The anisotropic conductive film or circuit board constituting the mounting substrate of the present invention, the bare chip state semiconductor element to be mounted on the mounting substrate of the present invention, and the like are as described in the description of the aspect (1) above. Is. Further, the elastic modulus of the entire anisotropic conductive film, which should be specified in order to preferably bond the semiconductor element, the anisotropic conductive film, and the circuit board, is the same as that described in the description of the aspect (1) above. Is. The bonding between the anisotropic conductive film and the circuit board, and the connection state between the conduction path and the mounting circuit are as follows: the bonding between the anisotropic conductive film and the semiconductor element described in the description of the aspect (1) above, and the conduction path. You may refer to the connection state with the electrode.

【0039】

[Example]

Example 1 In this embodiment, as an example of the aspect (1) above, a large-area anisotropic conductive film covering all of the semiconductor elements arranged on the wafer is bonded, the elements are divided, and the present invention is performed. The semiconductor device of the invention was manufactured. The anisotropic conductive film was produced by a manufacturing method including the steps listed above.

【0040】

[Semiconductor element] A semiconductor element (integrated circuit) of 10 mm × 10 mm formed in a matrix on a disk-shaped silicon wafer substrate having a diameter of 8 inch was used. Each electrode of the element is a flat Al pad.

【0041】

[Iteroconductive film] The specifications of the anisotropic conductive film as a single item before joining to the semiconductor element are as follows. The structure is a structure in which a copper wire having a diameter of 18 μm is held through a film substrate made of a polycarbodiimide resin to form a conduction path. The thickness of the film substrate is 60 μm, and both ends of the conduction path are projected from both sides of the film. The amount of the protrusions was the same on both sides, 0.5 μm each, and the protruding parts were further plated with gold with a thickness of 0.1 μm. Therefore, the total length of each conduction path is about 61.2 μm (= total thickness of the anisotropic conductive film). The outer peripheral shape of the anisotropic conductive film is the same as that of the wafer substrate, and all the semiconductor elements formed on the wafer substrate can be covered.

【0042】

The insulating conductor used for the winding in the manufacturing process of the anisotropic conductive film is a copper wire having a diameter of 18 μm coated with a polycarbodiimide resin to form a coating layer. As shown in Fig. 2 (a), the conduction paths are gathered in a nearly close-packed state due to the aligned winding at the time of winding, and the distance between the central axes of the two adjacent conduction paths is 40 μm. .. The elastic modulus of the entire structure of this anisotropic conductive film in the film plane direction was 3.0 GPa.

【0043】

The anisotropic conductive film is placed on a silicon wafer substrate in which the semiconductor elements are formed in a matrix, covered with a fluorine film, placed in an autoclave can, and different from the wafer under the conditions of 200 ° C and 10 kgf. A conductive film was attached. This state is the semiconductor device according to the above-mentioned (2), and the electrodes of all the elements are in a state where they can be connected to the outside via an anisotropic conductive film.

【0044】

The obtained semiconductor device according to the above (2) (a device in which a plurality of elements formed on a wafer are bonded with an anisotropic conductive film) is individually subjected to a semiconductor device (10 mm × 10 mm) by a dicing machine. The semiconductor device according to the above (1) was obtained.

【0045】

The obtained semiconductor device according to the above (1) can be mounted on the circuit board of the other party by using the flip chip bonder, which is a conventional mounting device, as it is. As a result, it was found that a three-layer structure mounting body in which an anisotropic conductive film is interposed, which is called [semiconductor element / anisotropic conductive film / circuit board], can be assembled with high productivity. In addition, the connection state between the semiconductor element and the circuit board with the anisotropic conductive film interposed is preferable because the occurrence rate of conduction failure is 0/200 in the thermal cycle test (-25 ° C to 125 ° C). there were.

【0046】

Example 2 In this embodiment, as an example of the aspect (4) above, the surface of the circuit board for enclosing the chip in the package (the surface of the circuit is solder-plated with a thickness of 21 μm) is anisotropically conductive. The films were joined to produce a mounting substrate of the present invention. The anisotropic conductive film was produced by a manufacturing method including the steps mentioned above, as in Example 1.

【0047】

[Semiconductor element to be mounted] This is a bare-chip integrated circuit with a thickness of 370 μm and an outer diameter of 10 mm × 10 mm. The electrodes are flat Al pads.

【0048】

[Circuit board] A circuit pattern made of copper is formed on a glass epoxy board (FR-4) with a thickness of 1 mm. The circuit pattern is formed as a circuit pattern corresponding to the electrodes of the semiconductor element to be mounted. The circuit width of the circuit pattern is 100 μm, and the width of the gap between adjacent circuits is 100 μm.

【0049】

[Anteroconductive film] The structural specifications and manufacturing method are the same as those used in Example 1. The outer shape of the film was 10 mm x 10 mm in consideration of the outer shape of the chip to be mounted.

【0050】

The anisotropic conductive film was placed on the area (position where the chips are bonded) to be occupied by the element on the mounting side surface of the circuit board, and bonded with a flip chip bonder to obtain the mounting substrate of the present invention. .. The joining conditions at this time are 180 ° C, 20 seconds, and a load of 20 kgf. Further, when using the flip chip bonder, a fluorine film is attached to the head portion (the portion originally in contact with the chip) of the bonder so that only the bonding function can be used.

【0051】

When the above-mentioned bare-chip state semiconductor element was tried to be mounted on the mounting substrate obtained above by using a flip-chip bonder which is a conventional mounting device, it was possible to mount the semiconductor element preferably. As a result, it was found that, as in Example 1, a three-layer structure mounting body in which an anisotropic conductive film is interposed, which is called [semiconductor element / anisotropic conductive film / circuit board], can be assembled with high productivity. .. Further, the connection state between the semiconductor element and the circuit board with the anisotropic conductive film interposed was preferable as in Example 1.

【0052】

[Effect of the invention]

According to the present invention, a conventional mounting device can be used while mounting a chip via an anisotropic conductive film. This has improved the productivity in the mounting process when manufacturing a three-way mounting body of a semiconductor element / anisotropic conductive film / circuit board.

[Simple explanation of drawings]

[Figure 1]

It is sectional drawing which shows the structure of the semiconductor device of this invention. The detailed internal structure of the semiconductor element 1 is omitted, and only the position of the electrode is shown. For the sake of explanation, the dimensional ratio of each part is exaggerated and changed. Hatching is used to distinguish between areas.

[Figure 2]

It is a schematic diagram which shows an example of an anisotropic conductive film used in this invention. FIG. 2A is a view of the film surface, and a part of the film surface is enlarged to show the arrangement pattern of the conduction path. FIG. 2 (b) shows the XX cross section of FIG. 2 (a).

[Fig. 3]

It is a schematic diagram which shows another example of the anisotropic conductive film used in this invention.

[Fig. 4]

It is a figure which shows an example of the arrangement pattern of the conduction path of the anisotropic conductive film used in this invention. Similar to FIG. 2A, it is a view of the film surface, and a part of the film surface is enlarged and shown, and does not show the outer peripheral shape of the film.

[Fig. 5]

It is sectional drawing which shows the structure of the board for mounting of this invention. The internal structure, interlayer connection structure, etc. of the circuit board 3 are omitted, and only the position of the mounting circuit 31 on the connection side with the anisotropic conductive film is shown. Also, because the mounting circuit 31 is exaggerated and drawn thick, the figure shows that there is a large gap between the anisotropic conductive film 2 and the circuit board 3, but in reality most of the parts are It is in close contact with.

[Explanation of symbols]

1 Semiconductor element 11 electrodes 2 Heteroconductive film 21 Conduction path 22 Film substrate