JP2000114280A - Adhesive film and semiconductor device employing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent undue projection of adhesive form adhesive layers formed on the opposite sides of an insulation film by setting the melting viscosity of the adhesive on the semiconductor chip side higher than that of the adhesive on the external wired joint member side at the hot press temperature thereby eliminating voids from the adhesion interface between the joint member and the semiconductor chip. SOLUTION: An adhesive has a semi-cured thermosetting resin layer 5 formed on the opposite sides of a core material, i.e., a heat resistant thermoplastic film 4, where the adhesive on the semiconductor chip side is cured more than the adhesive on the external wired joint member side so that the melting viscosity will be different on the opposite sides. In order to fill the irregularities formed on the surface of the external wired joint member due to a wiring layer or lands at hot press, melt viscosity of the adhesive on the external wired joint member side is preferably set in the range of 1 to 5×104 [P] at the hot press temperature. The melting viscosity of the adhesive on the semiconductor chip side is preferably set in the range of 2 to 8×104 [P] at the hot press temperature and is set higher than that of the adhesive on the external wired joint member side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double-sided adhesive film for bonding a semiconductor chip to a supporting member thereof, and a semiconductor device using the same.

[0002]

2. Description of the Related Art In recent years, with the increase in mounting density, semiconductor packages have been required to be smaller and lighter, and packages having been downsized to substantially the same size as semiconductor chips have been developed. The general structure of these semiconductor packages, so-called chip size packages, is to bond and hold a semiconductor chip to an external connection member having a wiring layer with an adhesive, and connect the chip and the external connection terminal by wire bonding or T-bonding.
Electrical connection is made by various methods such as inner lead bonding of AB (Tape Automated Bonding), and a part or the whole of the package is resin-sealed as required. In these semiconductor packages, a method in which a wiring layer of an external connection member made of a film substrate of polyimide or the like is arranged on a side in contact with an adhesive is called a circuit-in method. FIG. 1 shows a cross-sectional structure of the external connection member with wiring. In the circuit-in method, the surface of the external connection member on the side to be bonded to the adhesive film has unevenness due to a pattern called a land 2 for mounting a wiring 2 or a solder ball having a thickness of about 20 μm.

[0003] For this reason, when the adhesive film is thermocompression-bonded to the external connection member, voids are apt to be generated around the uneven portion of the external connection member. In addition, the film surface after bonding,
In order to adhere and adhere to the irregularities of the external connection member to some extent, slight irregularities also occur on the semiconductor chip bonding surface side, which causes voids at the semiconductor chip side interface. The voids generated on the external connection member side are improved by improving the embedding property of the adhesive between the wirings, and it is effective to reduce the melt viscosity of the adhesive at the thermocompression bonding temperature. However, if the melt viscosity is too low, the followability and the fluidity are increased, so that voids on the semiconductor chip side are liable to occur, the adhesive is protruded at the time of pressure bonding, the dimensional accuracy of the adhesive is deteriorated, and the pressure The tackiness to the tool increases, and the workability decreases. When the protrusion of the adhesive reaches the semiconductor chip pad portion or the inner lead bonding portion of the TAB of the external connection member, bonding may not be performed in some cases. In addition, if there is uneven adhesive protruding around the cutting edge of the adhesive film, this part will be the starting point and the package will be mounted on the mounting board in the reflow process and temperature cycle test at the interface between the external connection member or semiconductor chip and the adhesive film. There is a problem that large peeling occurs and the reliability of the package deteriorates.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a double-sided adhesive which is free from voids at an adhesive interface and does not cause excessive adhesive to protrude when an external connecting member with wiring and a semiconductor chip are thermocompression bonded with an adhesive film. Material film.

[0005]

The adhesive film of the present invention is an adhesive film for connecting a semiconductor chip and an external connection member with wiring supporting the semiconductor chip, the adhesive film having an adhesive layer on both sides of the insulating film, The semiconductor chip-side adhesive is characterized by having a higher melt viscosity at the thermocompression bonding temperature than the wiring-connected external connection member-side adhesive. Further, the adhesive film of the present invention is an adhesive film for connecting a semiconductor chip and an external connection member with wiring supporting the semiconductor chip, and has a thermosetting resin adhesive layer in a semi-cured state on both surfaces of the insulating film. The melt viscosity at the thermocompression bonding temperature of the adhesive is different on both surfaces. The adhesive film of the present invention is an adhesive film for connecting a semiconductor chip and an external connection member with wiring supporting the semiconductor chip, and is a thermosetting resin adhesive in a semi-cured state on both surfaces of an insulating film made of a polyimide resin. The semiconductor chip-side adhesive has a hardened state, which is hardened by the hardened state of the wiring-side external connection member-side adhesive. The semiconductor device of the present invention is one in which a semiconductor chip is bonded to an external connection member with wiring supporting the semiconductor chip with the above-mentioned adhesive film. In order to solve the above problems, the present inventors have proposed that an adhesive film connecting a semiconductor chip and an external connection member with wiring supporting the semiconductor chip has an adhesive layer on both surfaces of an insulating film, and a semiconductor chip-side adhesive. It was found that, by making the melt viscosity at the thermocompression bonding temperature higher than that of the adhesive on the side of the external connection member with wiring, voids at both bonding interfaces could be reduced and excess adhesive did not protrude. FIG.
Shows the cross-sectional shape of the adhesive film. The adhesive has a thermosetting resin layer 5 in a semi-cured state on both sides of a heat-resistant thermoplastic film 4 as a core material, and the adhesive on the semiconductor chip side is harder than the cured state on the external connection member side with wiring. As the curing proceeds, different melt viscosities are obtained on both surfaces.

More specifically, the adhesive film is made of an epoxy resin and its curing agent, a high molecular weight resin compatible with the epoxy resin, an epoxy group-containing acrylic resin on both sides of a heat-resistant thermoplastic film such as polyimide as a core material. It has a structure in which a semi-cured thermosetting adhesive composed of a copolymer and a curing accelerator is formed. Core material thickness is 25μ
Although the thickness of the adhesive layers on both sides may be the same or different at about m, the thickness of the adhesive on the side of the external connection member may be reduced in order to improve the embedding of the adhesive into the wiring layer of the external connection member. It is preferable to make it thicker than the side adhesive. The adhesive film can be produced by applying a thermosetting resin varnish to a base film in advance, producing a semi-cured film, and laminating the film on both sides of the core material. At this time, by laminating films in different states, adhesive films having different melt viscosities on both surfaces can be produced.

The adhesive on the side of the external connection member with wiring has a melt viscosity at a compression temperature of 1 to 5 × 10 ^{4 in} order to bury irregularities due to a wiring layer or a land on the surface of the external connection member during thermocompression.
[P] (measurement frequency: 10 [rad / s]) is preferable. FIG. 3 shows a cross-sectional view of the void 6 generated near the external connection member due to insufficient embedding. On the other hand, on the semiconductor chip side, since the adhesive film is in contact with the back surface of the semiconductor element (face-up method), there is no unevenness on the semiconductor chip surface adhesion surface. Therefore, the cause of void generation on the semiconductor chip side is that the adhesive film adhered first follows the unevenness of the external connection member with wiring, and the unevenness 7 is generated on the surface of the adhesive film. FIG. 4 shows a cross-sectional shape of the void 8 of the semiconductor chip caused by the unevenness of the surface of the adhesive film. Therefore,
If the melt viscosity of the adhesive on the semiconductor chip side is about the same as that of the external connection member with wiring, unevenness is transferred to the surface of the adhesive on the semiconductor chip side, which is not preferable. Further, if the pressure is increased or the temperature is increased in order to reduce voids due to the generated irregularities, the adhesive is excessively protruded, which is not preferable. The melt viscosity at the pressure bonding temperature of the adhesive on the semiconductor chip side is preferably 2 to 8 × 10 ⁴ [P]. As described above, by making the melt viscosity of the adhesive on the semiconductor chip side higher than that of the external connection member with wiring, voids at both bonding interfaces can be reduced, and excessive protrusion of the adhesive can be reduced.

[0008] The specific melt viscosity of the adhesive can be adjusted by controlling the semi-cured state of the adhesive varnish depending on the temperature and time during coating. It is also possible to adjust the resin composition and additives of the adhesive composition by adding inorganic fillers such as crystalline silica, amorphous silica, aluminum hydroxide, alumina, aluminum nitride and boron nitride.

In the method of connecting the semiconductor chip and the external connection member with wiring supporting the semiconductor chip by the adhesive film, first, the adhesive film cut into a predetermined size to the external connection member is aligned and thermocompression-bonded. The cutting method may be any method as long as it is cut to a predetermined size, but it is preferable to perform punching using a punching die in consideration of workability. Further, the semiconductor chip is thermocompression-bonded to an adhesive film adhered to the external connection member. The bonding condition of the adhesive to the external connection member with wiring and the semiconductor chip is not particularly limited as long as the adhesive can be adhered to the external connection member without defects such as voids or peeling, but the temperature is not limited to the heat resistance of the external connection member. From the viewpoint, the temperature is preferably from 60 to 250C, particularly preferably from 80 to 200C. The pressing pressure is preferably 5 to ²⁰ kgf / cm ² . If the pressure is lower than this, the adhesive is less likely to be embedded between the wirings on the side of the external connection member, and voids are likely to occur. If the pressure is higher than this, the dimensional accuracy of the extruded film of the adhesive deteriorates.
The pressing time is preferably 0.5 to 10 seconds in consideration of productivity.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Three types (A to C) of different semi-cured states consisting of an epoxy resin and its curing agent, a high molecular weight resin compatible with the epoxy resin, an epoxy group-containing acrylic copolymer, a curing agent accelerator and the like. A film of the thermosetting resin alone was produced. The melt viscosities of the individual films measured by a rheometer (Ares viscoelasticity measurement system manufactured by Rheometrics) are A: 4 × 10 ⁴ [P], B: 2.
5 × 10 ⁴ [P], C: 1.5 × 10 ⁴ [P]. The measurement frequency is 10 [rad / s] and the measurement temperature is 120
° C. Next, 25 μm Iupirex was used as a core material, and the above three types of films were laminated on both surfaces of the core material to produce an adhesive film. The adhesive film thickness on the external connection member side was 75 μm, and the adhesive film thickness on the semiconductor chip side was 50 μm. Using this adhesive film as an external connection member with wiring, a TAB made of a polyimide-based film
The tape was thermocompressed. The wiring width of the wiring layer is 30 μm,
A tape having a minimum wiring interval of 40 μm and a wiring layer thickness of 20 μm was used. Further, the semiconductor chip was pressed against the adhesive film, and the void at each adhesive interface and the protrusion amount of the adhesive were measured.

Example 1 An adhesive film on the side of the external connection member was used as C, and an adhesive film made of A was used as the adhesive film on the semiconductor chip side. The adhesive film was thermocompression-bonded to a TAB tape, and the semiconductor chip was thermocompression-bonded. Each crimping condition is 120 ℃ / 10kgf
/ Cm was ^2/5 seconds. After crimping, no defects such as voids were found at the bonding interface on the external connection member side and the bonding interface on the semiconductor chip side, and the protruding amount of the bonding material was approximately 60 μm.
This was within a range that would not cause a problem in inner lead bonding using a TAB film.

Example 2 Thermocompression bonding was performed in the same manner as in Example 1 except that the adhesive film on the external connection member side was changed to C and the adhesive film on the semiconductor chip side was changed to B in Example 1. After crimping, no defects such as voids were found at the bonding interface on the external connection member side and the bonding interface on the semiconductor chip side, and the protruding amount of the bonding material was about 80 μm, which was a range that would not cause a problem in inner lead bonding using a TAB film. Was.

Comparative Example 1 Thermocompression bonding was performed in the same manner as in Example 1 except that the adhesive film on the external connection member side was changed to C and the adhesive film on the semiconductor chip side was changed to C. After crimping, no defects such as voids were found at both the bonding interface on the external connection member side and the bonding interface on the semiconductor chip side. However, the amount of protrusion of the bonding material was about 200 μm and reached the lead portion of the TAB film, and the inner lead bonding was not performed. It was possible.

Comparative Example 2 Thermocompression bonding was performed in the same manner as in Example 1 except that the adhesive film on the external connection member side was changed to A and the adhesive film on the semiconductor chip side was changed to A. After bonding, no defects such as voids were found at the bonding interface on the semiconductor chip side, but voids were found at the bonding interface on the external connection member side due to insufficient embedding of the adhesive. On the other hand, the protruding amount of the adhesive was about 30 μm, which was a range that would not cause a problem in inner lead bonding using a TAB film.

Comparative Example 3 A thermocompression bonding was performed in the same manner as in Example 1 except that the adhesive film on the external connection member side was changed to A and the adhesive film on the semiconductor chip side was changed to C in Example 1. After bonding, no defects such as voids were found at the bonding interface on the semiconductor chip side, but voids were found at the bonding interface on the external connection member side due to insufficient embedding of the adhesive. On the other hand, the protruding amount of the adhesive was about 50 μm, which was a range that would not cause a problem in inner lead bonding using a TAB film.

[0016]

[Table 1]

[0017]

According to the present invention, a semiconductor device using a conventional adhesive film can be connected to an external connection member with wiring and a semiconductor chip without causing voids at the interface and extruding excessive adhesive. As compared with the first embodiment, an adhesive film having higher reliability and a semiconductor device using the same can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an external connection member with wiring to which an adhesive film of the present invention is applied.

FIG. 2 is a sectional view of an adhesive film according to the present invention.

FIG. 3 is a cross-sectional view when a conventional adhesive film is bonded to an external connection member.

FIG. 4 is a cross-sectional view when a semiconductor chip is bonded to a conventional adhesive film.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Film board 2 Wiring of wiring layer 3 Land of wiring layer 4 Core material of adhesive film 5 Adhesive layer of adhesive film 6 Void generated near external connection member with wiring 7 Adhesive film after bonding to external connection part Irregularities generated on the surface 8 Voids generated near the semiconductor chip

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masaaki Yasuda 48 Wadai, Tsukuba, Ibaraki Prefecture Hitachi Chemical Co., Ltd. Tsukuba Development Laboratories (72) Inventor Keiichi Hatakeyama 48 Wadai, Tsukuba City, Ibaraki Prefecture (72) Inventor: Hiroko Hara 48, Wadai, Tsukuba, Ibaraki Prefecture Within Tsukuba Development Laboratory, Hitachi Chemical Co., Ltd. (72) Inventor: Yoshihiro Nomura 14 Goi Minamikaigan, Ichihara, Chiba Pref. (72) Inventor Youichi Hosokawa 14 Goi South Coast, Ichihara City, Chiba Prefecture Hitachi Chemical Co., Ltd. Goi Plant F-term (reference) 5F047 BA33 BB03 BB13

Claims (4)

[Claims] 1. An adhesive film for connecting a semiconductor chip and an external connection member with wiring for supporting the semiconductor chip, the adhesive film having an adhesive layer on both surfaces of the insulating film, and the adhesive on the semiconductor chip side being an external connection with wiring. An adhesive film having a higher melt viscosity at a thermocompression bonding temperature than a member-side adhesive. 2. An adhesive film for connecting a semiconductor chip and an external connection member with wiring for supporting the semiconductor chip, wherein the adhesive film has a semi-cured thermosetting resin adhesive layer on both surfaces of the insulating film. An adhesive film characterized in that the melt viscosity at the thermocompression bonding temperature is different on both surfaces. 3. An adhesive film for connecting a semiconductor chip and an external connection member with wiring supporting the semiconductor chip, wherein a semi-cured thermosetting resin adhesive layer is provided on both surfaces of an insulating film made of a polyimide resin. An adhesive film, wherein the semiconductor chip-side adhesive is hardened by the hardened state of the wiring-connected external connection member-side adhesive. 4. A semiconductor device wherein a semiconductor chip is adhered to an external connection member with wiring supporting the semiconductor chip with the adhesive film according to claim 1.