JP2002176121A - Method for manufacturing semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device for realizing a small thin package suitable for mounting a small semiconductor chip by making a supporting board thin. SOLUTION: Two sheet of conductive foils 82 and 83, and a thermoplastic resin film 81 between them are subjected to thermo compression bonding in a body to form a supporting board 80. During the thermo compression bonding, a conductive material 87 for connecting both conductive foils 82 and 83 is so formed that the conductive material 87 is passed through the thermoplastic resin film 81 without using a via hole. Each electrode is formed from the conductive foil 82 and a semiconductor chip 88 is mounted. In the final step, each connection electrode is formed from the conductive foil 83, so the semiconductor chip 88 during the bonding can be prevented from the vertical shift. In this way, a greatly thin mounting structure can be realized by using a simple structure, and a semiconductor device optimum for mounting the small semiconductor chip can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device, and more particularly to a method of manufacturing a resin-sealed semiconductor device accommodating a small chip capable of forming an ultra-compact and thin package.

[0002]

2. Description of the Related Art In a conventional semiconductor device assembling process, a semiconductor chip separated by dicing from a wafer is fixed to a lead frame, and the semiconductor chip is sealed by a transfer mold using a mold and resin injection. A process of cutting and separating each semiconductor device is performed. In the semiconductor device obtained by this method, as shown in FIG. 8, the periphery of the semiconductor chip 1 is covered with the resin layer 2, and the lead terminals 3 for external connection are led out from the side of the resin layer 2. (For example, JP-A-05-129473).

[0003] This structure reduces the external dimensions and the mounting area due to the protrusion of the lead terminals 3 outside the resin layer 2, the problem of the processing accuracy of the lead frame and the problem of the positioning accuracy with the mold. Was seeing the limits.

In recent years, attention has been paid to a wafer-scale CSP (chip size package) capable of reducing an outer dimension to a size similar to or close to a semiconductor chip size. 9A, the semiconductor wafer 11 is subjected to various pretreatments such as diffusion to form a large number of semiconductor chips 12, and the upper portion of the semiconductor wafer 11 is formed as shown in FIG. 9B. Is covered with a resin layer 13, electrodes 14 for external connection are led out on the surface of the resin layer 13, and then the semiconductor chips 11 are divided along dicing lines of the semiconductor wafer 11, as shown in FIG. 9C. It is a finished product. The resin layer 13 only covers the front surface (the back surface may be covered) of the semiconductor chip 12, and the silicon substrate is exposed on the side wall of the semiconductor chip 12. The electrode 14 is electrically connected to an integrated circuit network formed below the resin layer 13, and the semiconductor device is mounted by bonding the electrode 14 to a conductive pattern formed on a mounting substrate. .

[0005] Such a semiconductor device has the advantage that the package size of the device is equivalent to the chip size of the semiconductor chip, and the device can be adhered to the mounting substrate by opposing, so that the area occupied by the mounting can be greatly reduced. Further, there is an advantage that the cost associated with the post-process can be significantly reduced. (For example, Japanese Patent Laid-Open No. 9-64049)
Although it is possible to arrange a large number of electrodes within the dimensions of a chip, for example, for a transistor chip having a chip size of less than 1 mm square, it is necessary to arrange a plurality of electrodes within this dimension. Has the drawback that it is physically unreasonable and difficult to implement even if realized.

Therefore, chips having a chip size of less than 1 mm square are mounted as shown in FIGS. 10A, 10B, and 10C. In the figure, reference numeral 21 denotes an insulating substrate made of ceramic, glass epoxy, or the like, and one or several of them are stacked to have a thickness of 250 to 350 μm, which can maintain the mechanical strength in the manufacturing process, and a long side. X It has a rectangular shape with a short side of about 1.0 mm x 0.8 mm.

On the surface of the insulating substrate 21, a conductive pattern is formed by printing a metal paste such as tungsten and gold plating on the metal paste by an electrolytic plating method to form an island portion 22 and electrode portions 23a and 23b. are doing. A semiconductor chip 25 is fixed on the island portion 22 by a conductive adhesive 24 such as an Ag paste.

An aluminum electrode pad 26 is formed on the surface of the semiconductor chip 25, and the electrode pad 26 and the electrode portion 23a are formed.
23b are electrically connected to each other by a bonding wire 27. 1st bond on electrode pad 26 side, electrode section 23
A 2nd bond is struck on the side. If it is a bipolar transistor, the electrode portions 23a and 23b correspond to the emitter and the base, and if it is a power MOSFET, it corresponds to the source and the gate.

A first external connection electrode 28 and second external connection electrodes 29a and 29b are formed on the back surface of the insulating substrate 21 by the same gold plating layer. A circular first via hole 30 and a second
Are formed, and the inside of each via hole 30, 31a, 31b is buried with a conductive material such as tungsten. The material is buried with a material having excellent electrical and thermal conductivity. The via hole 3
0, 31a and 31b, the island portion 22 and the first
Of the external connection electrode 28 and the electrode portions 23a and 23b and the second
Are electrically connected to the external connection electrodes 29a and 29b, respectively. The first external connection electrodes 28 are, for example, collector electrodes, and the second external connection electrodes 29a, 29b are, for example, base and emitter electrodes.

The semiconductor chip 25 is located above the insulating substrate 21.
And the bonding wire 27 is covered with a resin layer 32. The resin layer 32 forms an outer shape of the package together with the insulating substrate 21. The four sides around the package are resin layers 32
The upper surface of the package is formed on the flattened surface of the resin layer 32, and the lower surface of the package is formed on the back surface side of the insulating substrate 21.

However, there are various problems in the mounting structure shown in FIG. First, since an expensive metal paste such as tungsten is used, it cannot be said that the mounting structure is low cost. Secondly, in order to connect the electrodes and the like on both surfaces, a via hole penetrating the insulating substrate is indispensable.
Since the processing accuracy is limited to about 0.15 mm, it is an obstacle to further miniaturization. Third, since the inside of the via hole is filled with a metal paste, workability is extremely poor, which causes an increase in cost. Fourth, since the insulating substrate needs to have a thickness of 0.25 mm to 0.35 mm in order to maintain the mechanical strength, there are many problems such as hindrance to thinning.

Here, in order to solve the various problems described above, the following semiconductor device using a liquid crystal polymer for a supporting substrate has been proposed.

This embodiment will be described with reference to FIG.
FIGS. 11A and 11B are diagrams illustrating completed individual semiconductor devices. FIG. 11A is a plan view, FIG.
Is a sectional view at the time of bonding.

A support substrate 50 which is a feature of this semiconductor device
Is formed by thermocompression bonding two conductive foils on both surfaces of a thermoplastic resin film 51. The thermoplastic resin is softened by heating and is easily subjected to secondary processing, and is much easier to handle than a conventionally used ceramic or glass epoxy hard substrate. A liquid crystal polymer is most suitable as the thermoplastic resin. In this example, a wholly aromatic polyester liquid crystal polymer (Vectra) was used.

Two conductive foils which are separated by the resin film and electrically insulated are pressure-bonded to both surfaces of the thermoplastic resin film 51. As the conductive foil, an inexpensive copper foil having a small electric resistance is optimal. Specifically, 50μ
m on each side of the thermoplastic resin film 51 having a thickness of 20 m.
A copper foil having a thickness of μm is pressed. One conductive foil is etched and processed into a desired shape pattern to form the fixed electrode 54 and the extraction electrodes 55a and 55b. The fixed electrode 54 has a size and a shape at least on which the semiconductor chip 58 can be mounted, and a plurality of extraction electrodes 55a and 55b are formed adjacent to the fixed electrode 54 and slightly apart therefrom. The other conductive foil is also etched and processed into a desired shape pattern, and the fixed electrode 54 and the extraction electrode 5 are formed.
The connection electrodes 56, 56a,
Form 56b. The connection electrodes 56, 56 a, 56 b are formed in a size that can be soldered to a printed circuit board, are separated so that a solder bridge is not formed at the time of soldering, and the corresponding fixed electrodes 54 and extraction electrodes 55 are formed.
a and 55b. Note that the fixed electrode 5
4, extraction electrodes 55a and 55b and connection electrodes 56,
The surfaces 56a and 56b are covered with a nickel plating layer and a gold plating layer by electrolytic plating to reduce the contact resistance with the conductive paste and to enable the bonding of the fine bonding wires.

The conductive material 57 includes a fixed electrode 54 and lead electrodes 55a and 55b formed of one conductive foil and corresponding connection electrodes 56, 56a and 56b formed of the other conductive foil.
And are connected. A silver paste is used as the conductive material 57, and the thermoplastic resin 51 is heated and softened by heating.
Through. Therefore, it is not necessary to provide a via hole in advance. The position where the conductive material 57 is penetrated is shown in FIG.
(A) and (B), two fixed electrodes 54 are provided near the upper and lower ends on the side remote from the extraction electrodes 55a and 55b, and one is formed substantially at the center of the extraction electrodes 55a and 55b, as indicated by the broken circles. are doing.

The semiconductor chip 58 has Ag fixed on the fixed electrode 54.
It is fixed by a conductive paste 59 such as a paste. The semiconductor chip 58 is supplied from a wafer on which a three-terminal element such as a bipolar transistor or a power MOSFET or a two-terminal element such as a diode is formed. The semiconductor chip 58 itself has a high-concentration impurity layer on the back side like an N + / N-type structure, and through the high-concentration layer, connects one terminal of an anode or a cathode if it is a diode element. In the case of a bipolar transistor, the collector terminal is provided, and in the case of a power MOSFET, the drain terminal is provided, so that this high concentration layer is ohmically connected to the fixed electrode 54 via the conductive paste 59. .

An aluminum electrode pad 60 is formed on the surface of the semiconductor chip 58, and the electrode pad 60 and the extraction electrode 5 are formed.
5a and 55b are electrically connected by a gold wire bonding wire 61. 1st bond on the electrode pad 60 side,
A second bond is formed on the side of the extraction electrodes 55a and 55b55b. If it is a bipolar transistor, the extraction electrodes 55a and 55b correspond to the emitter and the base, and if it is a power MOSFET, it corresponds to the source and the gate.

The upper surface of the supporting substrate 50 is
8. Sealed with insulating resin 62 covering fixed electrode 54, extraction electrodes 55a and 55b and bonding wire 61. The insulating resin 62 forms a package outer shape together with the support substrate 51. The four peripheral sides of the package are formed by the cut surface of the insulating resin 62 and the support substrate 51, the upper surface of the package is formed by the flattened surface of the insulating resin layer 62, and the lower surface of the package is formed by the back surface of the support substrate 50. Insulating resin 6
2 uses a commonly used epoxy resin.

Here, a method of manufacturing this semiconductor device is shown in FIG.
This will be described with reference to FIG.

First Step: See FIGS. 13A, 13B and 13C In this step, first, a support substrate 50 is formed. As shown in FIG. 13A, a first conductive foil 52, a film 51 made of a thermoplastic resin, and a second conductive foil 53 are prepared. As the first and second conductive foils 52 and 53, inexpensive and low-resistance copper foil is suitable, and the surface in contact with the film 51 made of a thermoplastic resin and having a thickness of 20 μm is roughened into irregularities to increase the bonding strength. Like that. As the thermoplastic resin film 51, a liquid crystal polymer is optimal. On the surface of the second conductive foil 53, a silver paste, which is a conductive material 57, is screen-printed at a predetermined position, and the thermoplastic resin film 51 is formed.
The bump 110 is formed in advance at a height that penetrates.

Next, as shown in FIG. 13B, the first conductive foil 52, the thermoplastic resin film 51, and the second conductive foil 53 are thermocompression-bonded to form an integrated support substrate 50. During this thermocompression bonding, the thermoplastic resin film 51 is heated and softened, so that the bumps 110 serving as the conductive material 57 attached to the second conductive foil 53 are formed of the thermoplastic resin film 51.
And reaches the first conductive foil 52.

Further, when the thermocompression bonding is completed as shown in FIG. 13 (C), the first conductive foil 52, the thermoplastic resin film 51, and the second conductive foil 53 are tightly integrated and integrated.
The bump 110 made of the conductive paste is also crushed to 0.15.
A columnar conductive material 57 having a diameter of mm is formed.

Second step: See FIGS. 14A and 14B Both main surfaces of the support substrate 50 are covered with first and second conductive foils 52 and 53. As shown in FIG. 14A, a resist film 11 is formed on the first conductive foil 52 so as to cover the fixed electrode 54 having a predetermined shape and the extraction electrode 55.
1 on the second conductive foil 53,
Then, a resist film 111 is attached so as to cover the second connection electrodes 56, 56a, and 56b.

Subsequently, as shown in FIG. 14B, using the resist film 111 as a mask, the first and second conductive foils 52 and 5 are used.
3 is chemically etched using a ferric chloride solution,
The fixed electrode 54 and the extraction electrode 55 are formed by the first conductive foil 52.
a and 55b are formed, and the first and second connection electrodes 56, 56a and 56b are formed by the second conductive foil 53.

Third Step: See FIG. 15 A semiconductor chip 58 is die-bonded to the support substrate 50 on which the electrodes are formed as described above. The semiconductor chip 58 has a conductive paste 59 such as an Ag paste on the surface of the fixed electrode 54.
Fixed by

Fourth step: See FIGS. 16A and 16B The electrode pad 60 and the extraction electrode 55 of the semiconductor chip 58
a and 55b are connected by bonding wires 61 such as gold. In the case of performing ball bonding with a gold wire, the supporting substrate 50 is heated to 150 ° C., and the ball portion formed at one end of the gold wire is thermocompression-bonded to the electrode pad 60 of the semiconductor chip 58, and multiple ends are taken out to the electrodes 55a and 55b. Thermocompression bonding.

Fifth step: See FIG. 17 When the die bonding of the semiconductor chip 58 and the connection by the bonding thin wire 61 to each mounting portion of the support substrate 50 are completed, the entire molding is performed by the insulating resin 62. In this step, the connection electrodes 56, 56a, 5
Except for 6b, the semiconductor chip 58, the fixed electrode 54, the extraction electrodes 55a and 55b, and the bonding thin wires 61 are covered with an epoxy resin 62.

[0029]

However, there is an important problem in the mounting structure shown in FIG. That is, the liquid crystal polymer serving as the support substrate is very soft. In such a semiconductor device, the connection electrode is formed smaller in structure than the fixed electrode and the extraction electrode. As a result, as shown in FIG. 13A, when a portion having no connection electrode is electrically connected by a gold bonding wire, the substrate cannot withstand the pressing force and is distorted. There is a problem of not being transmitted.

[0030]

SUMMARY OF THE INVENTION The present invention has been made in view of the various problems described above, and comprises a first conductive foil,
A soft resin and a second conductive foil having a conductive material adhered to a desired position are thermocompressed to penetrate the conductive material through the soft resin to electrically connect the first and second conductive foils. A step of forming a support substrate, a step of forming a fixed electrode and a take-out electrode with the first conductive foil, a step of fixing a semiconductor element to the fixed electrode using a conductive paste, A step of bonding and connecting the extraction electrode, a step of exposing the second conductive foil and covering the whole with an insulating resin, and a step of electrically connecting the second conductive foil with the conductive material corresponding to the fixed electrode and the extraction electrode. Forming a connection electrode that is electrically connected.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. 1A and 1B are diagrams illustrating a completed individual semiconductor device of the present invention, wherein FIG.
(B) is a sectional view, and (C) is a back view. 2A and 2B are diagrams illustrating a support substrate used in the present invention, wherein FIG. 2A is a plan view and FIG. 2B is a rear view.

The support substrate 80 of the present invention is formed by thermocompression bonding two conductive foils 82 and 83 (see FIG. 3) on both surfaces of a thermoplastic resin film 81. The thermoplastic resin is softened by heating and is easily subjected to secondary processing, and is much easier to handle than a conventionally used ceramic or glass epoxy hard substrate. As described above, a liquid crystal polymer is most suitable as the thermoplastic resin. In this embodiment, a wholly aromatic polyester-based liquid crystal polymer (Vectra) is used.

Two conductive foils 82 and 83 which are separated by the resin film and electrically insulated are pressed on both surfaces of the thermoplastic resin film 81. As the conductive foil, an inexpensive copper foil having a small electric resistance is optimal. Specifically, copper foils 82 and 83 each having a thickness of 20 μm are pressure-bonded to both surfaces of a thermoplastic resin film 81 having a thickness of 50 μm. One conductive foil 82 is etched and processed into a desired shape pattern, and the fixed electrode 84 and the extraction electrode 85 are formed.
a and 85b are formed. The fixed electrode 84 has at least a size and a shape on which the semiconductor chip 88 can be mounted.
A plurality of extraction electrodes 85a and 85b are formed adjacent to the fixed electrode 84 and slightly apart therefrom.

The other conductive foil 83 is also etched and processed into a desired pattern, and the connection electrodes 86 and 86 are located at positions facing the fixed electrode 84 and the extraction electrodes 85a and 85b.
a and 86b are formed. Connection electrodes 86, 86a, 86b
Is formed in a size that can be soldered to a printed circuit board,
In order to prevent formation of a solder bridge during soldering, the corresponding fixed electrode 84 and extraction electrode 8 are separated.
It is formed smaller than 5a and 85b. Note that the fixed electrode 8
4, take-out electrodes 85a, 85b and connection electrodes 86,
The surfaces 86a and 86b are covered with a nickel plating layer and a gold plating layer by electrolytic plating to reduce the contact resistance with the conductive paste and to enable the bonding of the bonding thin wires.

The conductive material 87 connects the fixed electrode 84 and the lead electrodes 85a and 85b formed of one conductive foil 82 to the other connection electrodes 86a and 86b. A silver paste is used as the conductive material 87, and the thermoplastic resin 81 is heated and softened to penetrate the conductive material 87. Therefore, it is not necessary to provide a via hole in advance. The position through which the conductive material 87 is penetrated is indicated by a broken-line circle in FIGS.
Two fixed electrodes 84 are provided near the upper and lower ends on the side distant from the extraction electrodes 85a and 85b.
5b, one is formed almost at the center.

The semiconductor chip 88 has Ag fixed on the fixed electrode 84.
It is fixed by a conductive paste 89 such as a paste. The semiconductor chip 88 is supplied from a wafer on which a three-terminal element such as a bipolar transistor or a power MOSFET or a two-terminal element such as a diode is formed. The semiconductor chip 88 itself has a high-concentration impurity layer on the back surface like an N + / N-type structure, and through the high-concentration layer, connects one terminal of an anode or a cathode if it is a diode element. In the case of a bipolar transistor, the collector terminal is provided, and in the case of a power MOSFET, the drain terminal is provided, so that this high-concentration layer is ohmically connected to the fixed electrode 84 via the conductive paste 89. .

An aluminum electrode pad 90 is formed on the surface of the semiconductor chip 88, and the electrode pad 90 and the extraction electrode 8 are formed.
5a and 85b are electrically connected by a gold wire bonding wire 91. 1st bond on the electrode pad 90 side,
A second bond is formed on the extraction electrodes 85a and 85b. If it is a bipolar transistor, the extraction electrode 8
5a and 85b correspond to the emitter and the base, respectively.
If it is an SFET, it corresponds to the source and the gate.

The upper surface of the thermoplastic resin film 81 has the semiconductor chip 88, the fixed electrode 84, and the mounting electrodes 85a, 8
5b and the bonding wire 91 are sealed with an insulating resin 92. The insulating resin 92 forms a package outer shape together with the thermoplastic resin film 81. The four sides around the package are insulating resin 92 and thermoplastic resin film 8
1, the upper surface of the package is formed on the flattened surface of the insulating resin layer 92, and the lower surface of the package is formed on the back surface of the thermoplastic resin film 81. As the insulating resin 92, a commonly used epoxy resin is used.

Next, referring to FIG. 2, fixed electrode 84 and extraction electrodes 85a and 85b formed from one conductive foil 82 on the upper surface of support substrate 81, and the other conductive foil 8 on the back surface.
The relationship between the connection electrodes 86, 86a and 86b formed from 3 will be described.

Each mounting section 100 surrounded by a dotted line has a rectangular shape of, for example, 0.9 mm × 0.8 mm long side × short side, and these are spaced apart from each other by 20 to 50 μm.
They are arranged vertically and horizontally on a matrix of 4 rows and 24 columns. The interval becomes a dicing line 101 in a later step. The conductive pattern forms the fixed electrode 84 and the extraction electrodes 85a and 85b in each mounting portion 100, and these patterns have the same shape in each mounting portion 100.

From the fixed electrode 84, two connecting portions 102 are extended in a continuous pattern. These line widths are narrower than the fixed electrode 84 and extend with a line width of, for example, 0.075 mm. The connecting portion 102 extends beyond the dicing line 101 to the extraction electrodes 85a, 85b of the adjacent mounting portion 100.
Extend until connected to Further, the connecting portion 103 extends vertically from the fixed electrode 84 in a direction perpendicular to the connecting portion 102 and extends beyond the dicing line 101 until the connecting portion 103 is connected to the fixed electrode 84 of the adjacent mounting portion 100. . The connection portion 103 is further connected to a common connection portion 104 surrounding the periphery of the mounting portion 100, and the fixed electrode 84 of each mounting portion 100 is connected.
And the extraction electrodes 85a and 85b are electrically connected in common.

On the back side of the thermoplastic resin film 81,
First and second connection electrodes 86, 86a, 86b are formed. These connection electrodes 86, 86a, 86b are formed in a pattern recessed from the end of the mounting portion 100 by about 0.05 to 0.1 mm. The thermoplastic resin film 81 separating the two conductive foils 82 and 83 is penetrated by a conductive material 87 at a position shown by a circle to be electrically connected. Specifically, the fixed electrode 84 and the first connection electrode 86 are connected to each other by two conductive materials 87 provided on the upper and lower sides.
a and 85b are connected to the second connection electrodes 86a and 86b by a conductive material 87 provided at the center thereof. Therefore, each electrode is connected to the common connection portion 104 on the front surface side of the thermoplastic resin film 81 via the conductive material 87. Therefore, each of the thin connecting portions 103 and 104 is cut after dicing to function as an individual electrode. Since all the patterns are electrically connected in common, it is possible to cover the surface of each electrode with a nickel plating layer and a gold plating layer by an electrolytic plating method.

Since the thermoplastic resin 81 is softer than a ceramic or glass epoxy substrate, there is a disadvantage that a bonding pressure is diverged during bonding. In order to prevent this, the manufacturing method of the present invention is effective.

In the present invention, in the final step, the conductive foil 83 is etched and processed into a desired shape pattern,
Since the connection electrodes 86, 86a, 86b are formed at positions facing the electrode 4 and the extraction electrodes 85a, 85b, bonding pressure does not diverge during bonding, so that a soft failure caused by thermoplasticity can be removed. is there. Moreover, there are many advantages of using a liquid crystal polymer as the thermoplastic resin film. In electrical characteristics, the dielectric constant is 1 MH (20 ° C., 96 H, 65% R
H) is 3.0, and 2.9 at 1 GHz, which is considerably better than that of a glass epoxy substrate having a dielectric constant of 4.7 to 5.0 at 1 MHz. The surface resistance is 14 × 10 ¹³ Ω, which is much higher than the polyimide resin 1.1 × 10 ¹³ Ω. From these, it is apparent that the support substrate of the present invention has excellent characteristics in an extremely high frequency range. Further, the folding resistance is 44 times at R = 0.38 mm according to the JIS C5016 evaluation standard, and under the same conditions, the number of breaks in the fine wire is smaller than that of the polyimide resin 33 times. Furthermore, it has a water absorption of 0.04%, good insulation under humidity, high gas barrier properties, and is environmentally friendly with no halogen and no through-hole plating.

Next, a method of manufacturing a semiconductor device according to the present invention will be described with reference to FIGS.

First Step: See FIGS. 3A, 3B and 3C In this step, first, a support substrate 80 is formed. As shown in FIG. 3A, a first conductive foil 82, a film 81 made of a thermoplastic resin, and a second conductive foil 83 are prepared. As the first and second conductive foils 82 and 83, an inexpensive and low-resistance copper foil is suitable, and the surface contacting the film 81 made of a thermoplastic resin having a thickness of 20 μm is roughened into irregularities to increase the bonding strength. Like that. As the thermoplastic resin film 81, a liquid crystal polymer is most suitable. In this example, a wholly aromatic polyester liquid crystal polymer (Vectra) was used. As described above, this wholly aromatic polyester-based liquid crystal polymer has a melting point of 325 as a physical property.
° C and solder heat resistance are 320 ° C, and can be sufficiently used as a mounting substrate for a semiconductor element. This can be easily understood from the fact that the solder heat resistance of the glass epoxy substrate is 260 ° C., for example. On the surface of the second conductive foil 83, a silver paste as a conductive material 87 is screen-printed at a predetermined position, and a bump 120 is formed in advance at a height (for example, 50 μm or more) penetrating the thermoplastic resin film 81. .

The first and second conductive foils 82 and 83 and the thermoplastic resin film 81 are initially supplied in the form of a roll having a width of 1 m, formed into a large number of support substrates 80, and then separated into individual support substrates 80. . This individual support substrate 80 is shown in FIG.
The mounting portion 100 of 576 semiconductor elements is formed in four rows.

Next, as shown in FIG. 3B, the first conductive foil 82, the thermoplastic resin film 81 and the second conductive foil 83 are thermocompression-bonded to form an integrated support substrate 80. During this thermocompression bonding, the thermoplastic resin film 81 is heated and softened, so that the bumps 120 serving as the conductive material 87 attached to the second conductive foil 83 are formed of the thermoplastic resin film 81.
And reaches the first conductive foil 82. When a liquid crystal polymer is used as the thermoplastic resin film 81, vacuum thermocompression is performed at a heating temperature of 300 ° C. and a compression pressure of 4.4 to 8.7 kPa. At this time, since the liquid crystal polymer is considerably softened near the glass transition point, a bump 120 having a sharp tip made of a conductive paste penetrates the liquid crystal polymer. At this time, no adhesive was used.

Further, when the thermocompression bonding is completed as shown in FIG. 3C, the first conductive foil 82 and the thermoplastic resin film 8
Since the first and second conductive foils 83 are tightly integrated, the bumps 120 made of the conductive paste are also crushed by 0.15 m.
A columnar conductive material 87 having a diameter of m is formed.

Second step: See FIGS. 4A and 4B Both main surfaces of the support substrate 80 are covered with first and second conductive foils 82 and 83. As shown in FIG.
The fixed electrode 8 having a predetermined shape is formed on the first conductive foil 82.
4. A resist film 112 is formed so as to cover the extraction electrode 85.
And the second conductive foil 83 is kept flat. As the resist film 112, a liquid resist material may be spin-coated and subjected to photosensitive development, or a film-shaped resist material may be attached and subjected to photosensitive development.

Subsequently, as shown in FIG. 4B, using the resist film 112 as a mask, the first conductive foil 82 is chemically etched using a ferric chloride solution to form the first conductive foil 82.
To form the fixed electrode 84 and the extraction electrodes 85a and 85b. Since all of these electrodes are electrically connected by the connection electrodes 102 and 103 and the conductive material 87, a nickel plating layer (5 μm or more) serving as a base for gold plating is formed on these electrodes by electrolytic plating, and gold plating is performed thereon. Layer (0.5μ
m or more).

Third step: see FIG. 5 A semiconductor chip 88 is die-bonded to each mounting portion 100 of the support substrate 80 on which the electrodes are formed as described above. The semiconductor chip 88 is fixed to the surface of the fixed electrode 84 by a conductive paste 89 such as an Ag paste. After the conductive paste 89 is attached by screen printing on the fixed electrodes 84 of the individual support substrates 80, the semiconductor chip 88 is placed thereon,
The thermoplastic resin film is cured in an electric furnace in a reducing atmosphere at a temperature of about 150 ° C. below a glass transition point of 205 ° C. for about 30 minutes.

Fourth step: See FIG. 6 The electrode pads 90 of the semiconductor chip 88 and the extraction electrodes 85
a and 85b are connected by bonding wires 91 such as gold. In the case of performing ball bonding with a gold wire, the supporting substrate 80 is heated to 150 ° C., and a ball portion formed at one end of the gold wire is thermocompression-bonded to the electrode pad 90 of the semiconductor chip 88, and multiple ends are taken out to the electrodes 85a and 85b. Thermocompression bonding.
At this time, since the second conductive foil 83 on the back surface side of the support substrate 80 is in a flat state, the bonding pressure does not diverge during bonding, so that it is possible to remove a soft failure caused by thermoplasticity. The sinking of the chip 88 in the vertical direction can be suppressed, and the loop shape of the bonding thin wire can be stabilized.

Fifth Step: See FIGS. 7A, 7B and 7C When the die bonding of the semiconductor chip 88 and the connection by the fine bonding wires 91 are completed on each mounting portion of the supporting substrate 80, the entire molding is performed by the insulating resin 92. I do. In this step, except for the second conductive foil 83 exposed on the back surface of the support substrate 80,
Semiconductor chip 88, fixed electrode 84, extraction electrode 85
a, 85 b and the bonding thin wire 91 are covered with an epoxy resin 92.

Subsequently, as shown in FIG.
Fixed electrode 54 and extraction electrode 55a on conductive foil 83 of
Connection electrodes 56, 56a, 56b
A resist film 112 is attached so as to cover.

Subsequently, as shown in FIG. 7C, the second conductive foil 83 is chemically etched using a resist film 112 as a mask using a ferric chloride solution to form a second conductive foil 8.
3, the connection electrodes 56, 56a and 56b are formed.

[0057]

According to the present invention, firstly, the entire surface of the soft resin is supported by the second conductive foil at the time of bonding by forming the connection electrodes after the completion of the bonding. Stable bonding can be realized.

Second, since each electrode is formed of two conductive foils and a conductive material, an expensive metal paste such as tungsten conventionally used is not required, and there is an advantage that an extremely inexpensive mounting structure can be realized. When a copper foil is used as the conductive foil, the electric resistance can be reduced, and the saturation on-resistance can be greatly improved.

Third, since a thermoplastic resin film is used as an interlayer insulating film between the two conductive foils, the formation of via holes and through-hole plating can be eliminated, and the conductive material can be used when the thermoplastic resin film is thermocompressed. It is possible to provide a very simple mounting structure that can electrically connect the electrodes formed of both conductive foils only by penetrating. For this reason, a non-halogen, no through-hole plating and extremely environmentally friendly mounting structure is obtained.

Fourth, the supporting substrate of the present invention has a copper foil of about 20 μm.
m, since the thermoplastic resin film is formed with a thickness of about 50 μm, the overall thickness can be at most 90 μm, and the thickness of a conventional ceramic substrate is only 0.25 mm to 0.35 mm with ceramic alone, and is about 1/3 thin. It has the advantage that it can be. For this reason, it can greatly contribute to the reduction in thickness of the completed semiconductor device, and is most suitable for a mounting structure of an extremely fine transistor chip of 1 mm × 1 mm or less.

Fifth, the thermoplastic resin film used in the present invention has the same dielectric constant in the high-frequency region as the polyimide resin, and has the same surface resistance as the glass epoxy substrate, so that good high-frequency characteristics can be obtained.

[Brief description of the drawings]

FIG. 1A is a plan view illustrating a semiconductor device of the present invention,
(B) is a sectional view, (C) is a back view.

FIGS. 2A and 2B are a plan view and a rear view illustrating a support substrate used in the present invention. FIGS.

FIG. 3 is a cross-sectional view illustrating a method for manufacturing a semiconductor device of the present invention.

FIG. 4 is a cross-sectional view illustrating a method for manufacturing a semiconductor device of the present invention.

FIG. 5 is a sectional view illustrating the method for manufacturing a semiconductor device according to the present invention;

FIG. 6 is a cross-sectional view illustrating a method for manufacturing a semiconductor device of the present invention.

FIG. 7 is a sectional view illustrating the method for manufacturing a semiconductor device according to the present invention;

FIG. 8 is a cross-sectional view illustrating a conventional semiconductor device.

9A is a plan view, FIG. 9B is a sectional view, and FIG. 9C is a perspective view illustrating a conventional semiconductor device.

10A is a plan view, FIG. 10B is a cross-sectional view, and FIG. 10C is a rear view illustrating a conventional semiconductor device.

11A is a plan view and FIG. 11B is a rear view illustrating a conventional semiconductor device.

FIG. 12 is a cross-sectional view illustrating a conventional semiconductor device.

FIG. 13 is a cross-sectional view illustrating a conventional method for manufacturing a semiconductor device.

FIG. 14 is a cross-sectional view illustrating a method for manufacturing a conventional semiconductor device.

FIG. 15 is a cross-sectional view illustrating a method for manufacturing a conventional semiconductor device.

FIG. 16 is a cross-sectional view illustrating a conventional method for manufacturing a semiconductor device.

FIG. 17 is a cross-sectional view illustrating a conventional method for manufacturing a semiconductor device.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Shigeru Fujii 2-5-2-5 Keihanhondori, Moriguchi-shi, Osaka F-term (reference) in Sanyo Electric Co., Ltd. 5F044 AA02 CC07

Claims (7)

[Claims] 1. A first conductive foil, a soft resin, and a second conductive foil having a conductive material adhered to a desired position are thermocompression-bonded to penetrate the conductive material through the soft resin to form the first conductive foil. And the second
Forming a support substrate for electrically connecting the conductive foils, forming a fixed electrode and a lead-out electrode with the first conductive foil, and fixing a semiconductor element to the fixed electrode using a conductive paste. Bonding the electrode of the semiconductor element to the take-out electrode; exposing the second conductive foil to cover the whole with an insulating resin; and taking the fixed electrode and take-out with the second conductive foil. Forming a connection electrode corresponding to the electrode and electrically connected by the conductive material. 2. The fixed electrode, the extraction electrode and the connection electrode are formed by chemical etching using a copper foil as the first and second conductive foils.
The manufacturing method of the semiconductor device described in the above. 3. The method according to claim 1, wherein a thermoplastic resin is used as the soft resin. 4. The method according to claim 1, wherein a liquid crystal polymer is used as the thermoplastic resin. 5. The method according to claim 1, wherein a silver paste is used as the conductive material. 6. The method according to claim 1, wherein a silver paste is used as the conductive paste for fixing the semiconductor element, and the silver paste is cured at a temperature equal to or lower than a glass transition point of the thermoplastic resin film. A method for manufacturing a semiconductor device. 7. The method of manufacturing a semiconductor device according to claim 1, wherein the coating of the insulating resin is performed by transfer molding at a temperature equal to or lower than a glass transition point of the thermoplastic resin film.