JPH09249861A - Bonding material and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a bonding material, excellent in thermal conductivity and adhesion, initiating no crack and useful for production, etc., of a semiconductor device having high reliability without short-circuiting between the wirings, etc., by including a thermoplastic resin having reactive functional groups, a tackifier, a cross-linking agent and a specific filler therein. SOLUTION: This adhesive substance comprises (A) a main component composed of a thermoplastic resin having reactive functional groups, (B) a tackifier, (C) a cross-linking agent and (D) a filler having the smooth surface (e.g. a spherical or ellipsoidal material which is a fused or a crystal silica previously coupling-treated by a glycidyl-based silane coupling agent, having 3-30&mu;m number-average particle diameter D50, containing no particle having <=1&mu;m or having >=1&mu;m particle diameter D5 at 5% point). A semiconductor device is obtained by using the bonding material for adhering between a base plate and a wiring layer in the device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive material and a semiconductor device using the same. In recent years, electronic devices such as personal computers have been downsized,
There is a demand for miniaturization, and accordingly, there is a demand for miniaturization of semiconductor devices mounted in electronic devices.

Further, since the heat radiation characteristic is deteriorated by miniaturizing the semiconductor device, it is necessary to provide an efficient heat radiation means. Therefore, there is a demand for a semiconductor device that can realize miniaturization and has a high heat conduction (heat dissipation) rate.
An adhesive material required to form the semiconductor device is desired. Further, also in fields other than semiconductor devices, there is a widespread demand for adhesive materials that can be obtained at low cost and have a reliable adhesive force for bonding different or similar materials.

[0003]

2. Description of the Related Art FIG. 1 shows a semiconductor device 2 having a good heat dissipation property.
00 shows an example. FIG. 2 shows AA ′ in FIG.
It is sectional drawing along the line. In each figure, reference numeral 1 denotes a semiconductor element, which is fixed on a die pad 39 of a base substrate 2 (hereinafter, simply referred to as a substrate) by a dan bond layer 18. The substrate 2 is made of a metal material having good thermal conductivity, and a resin-filled recess 53 is formed in the lower portion thereof.

A multi-layer wiring board 55 is arranged on the surface of the substrate 2 on which the semiconductor element 1 is arranged. The wiring board 55 is composed of the insulating layer 9 and the wiring layer 15, and the multilayer wiring board 55 is sandwiched between the insulating layers 9 and insulated. The wiring layer 15 is generally formed of a polyimide film to which copper wiring is applied, an epoxy-based or maleimide-based printed board, or the like.

A frame body 5 is arranged at a predetermined position on the substrate 2 so as to surround the semiconductor element 1, and an upper lid body 7a is arranged above the frame body 5. The frame body 5 and the upper lid body 7a are both formed of a metal material having good thermal conductivity, and are joined by brazing, adhesion, welding, or the like. The insulating layer 9 that adheres the wiring layer 15 and the substrate 2 is made of an insulating adhesive material. Specifically, the adhesive layer is formed by a liquid paste and an adhesive sheet, or a liquid is previously formed on the substrate or the frame. It was formed by a method (precoating method) of applying the adhesive material, then drying to remove the solvent, and thermocompression-bonding the wiring layer 15 and the substrate 2.

Further, the insulating layer 9 used for bonding the frame 5 and the substrate 2 is also a liquid paste, an adhesive sheet,
Or by a method such as bonding by the precoat method,
Had been formed. The precoat method will be further described. In the adhesive material used in the precoating method, a thermosetting resin or a thermoplastic resin is added as a binder resin, which is diluted with a solvent to a viscosity at which it can be precoated, and a filler or the like is further added if necessary. When manufacturing the semiconductor device 200, the adhesive material is applied to the substrate 2 or the frame 5 and exposed to a temperature of 40 to 120 ° C. to scatter the solvent. Then, the wiring layer 15 is set to 60 to 1
Pressure bonding is performed at a temperature of 70 ° C., and if necessary, the adhesive material is post-cured to form an insulating layer.

At the time of thermocompression bonding, the dried and solidified binder resin is melted and the substrate 2 and the wiring layer 15, and further the insulating layer is fused to the substrate 2 and the frame 5, so that the substrate 2 and the wiring layer 15, and further , The substrate 2 and the frame body 5,
Glued. As a binder resin, thermosetting resin,
Epoxy resins, maleimide resins, and the like are used, and thermoplastic resins include phenoxy resins, butyral resins, and styrene-ethylene-containing a reactive functional group such as a carboxyl group, which are described in JP-A-5-182515. Butylene-styrene copolymer and the like are used. It is advantageous to use a thermoplastic resin as the binder resin in order to relieve the stress generated by bonding different materials.

[0008]

As described above, it is essential that the insulating layer 9 efficiently conducts the heat generated by the operation of the semiconductor element 1 to the substrate 2 and the frame body 5. Therefore, it is essential that voids are unlikely to occur in the layer as the form of the die bond layer and the insulating layer. However, in the conventional die bond material, since many voids are generated when the die bond agent is cured, it is difficult to efficiently conduct the heat generated by the semiconductor element to the substrate.

On the other hand, as an adhesive material used in the precoating method, which is advantageous in terms of voidlessness and workability, Japanese Patent Laid-Open No.
An adhesive to which a filler is added in order to increase the thermal conductivity is used in the adhesive material described in Japanese Patent Publication No. 182515. In order to improve the heat conduction of the adhesive layer itself, a means for increasing the surface area of the filler in the adhesive has been taken by making the shape of the added filler amorphous. However, since an adhesive containing an amorphous filler has poor fluidity during thermocompression bonding, adhesion at the interface of the adherend cannot be ensured, and the thermal conductivity between the adhesive layer and the adherend is significantly reduced. There was a problem. Also, usually 1 in the filler
A large number of particles smaller than μm are also included. An adhesive to which a filler containing particles of less than 1 μm is added has a problem that the fine powder reduces the fluidity during thermocompression bonding, resulting in a decrease in the adhesiveness at the adherend interface.

When a heat-crosslinking type adhesive is used,
It goes through a curing process of heating (150 to 170 degrees) and cooling (heating temperature to room temperature). The morphology after curing of the adhesive has a sea-island structure in which the reactive rubber elastic polymer is used as a matrix and the crosslinking agent forms domains. Therefore, during cooling during curing of the adhesive, a difference in thermal expansion between the rubber / crosslinking agent causes stress at the rubber / crosslinking agent interface, so that the cured adhesive has a width of 0.1 to 0.5 μm and a length of 2 μm. ~ 10 μm
Some microcracks occur. In an LSI package using an adhesive having microcracks, moisture enters through the cracks during operation, causing a problem such as a short circuit between wirings.

On the other hand, when a hygroscopic package using an adhesive having microcracks is mounted on a mounting board, the package may absorb moisture depending on the storage condition. In that case, the adhesive layer cracks due to thermal stress during mounting. Since the moisture inside expands and vaporizes rapidly, so-called popcorn cracks occur in the adhesive layer. There is a problem that this popcorn crack becomes a factor that further reduces the reliability of the package.

[0012]

In order to solve the above-mentioned problems, the present invention comprises, in one aspect, a thermoplastic resin having a reactive functional group as a main component, and a tackifier, a cross-linking agent and a filler. In the adhesive material, the adhesive material is characterized in that the filler has a smooth surface shape.

In another aspect of the present invention, a filler is preliminarily subjected to a coupling treatment in an adhesive material containing a thermoplastic resin having a reactive functional group as a main component and a tackifier, a crosslinking agent and a filler. Provided is an adhesive material characterized in that It is preferable that these fillers have a number average particle size D50 of 3 to 30 μm and do not contain particles having a particle size of less than 1 μm or have a 5% particle size D5 of 1 μm or more.

The above-mentioned adhesive material may be a sheet-like adhesive material. In a third aspect of the present invention, the above adhesive material is used as a substrate on which a semiconductor element is mounted, a semiconductor device using the adhesive material between wiring layers, a substrate on which the semiconductor element is mounted, and a semiconductor element There is also provided a semiconductor device used as an adhesive material between.

[0015]

The above means will be described in more detail. The reactive thermoplastic resin that is the main component,
Any resin may be used as long as it is soluble in a solvent to form a varnish, but in particular, a styrene-ethylene / butylene-styrene copolymer having a reactive functional group such as a carboxyl group, a styrene-butadiene-styrene copolymer, etc. Polymers, styrene-polyisoprene-styrene copolymers, and hydrogenated products of the above copolymers. Maleic anhydride grafted polypropylene, carboxylic acid modified polyethylene, maleic anhydride grafted polypropylene, maleic anhydride grafted ethylene propylene rubber and the like are used.

As the filler, an insulating inorganic substance such as fused silica, alumina and aluminum nitride, and a metal powder such as silver, copper and aluminum can be used according to the purpose. In the first aspect of the present invention, the filler has a smooth surface,
For example, the shape may be spherical, elliptical, or the like. If the surface has a smooth surface shape such as a sphere compared to a rough irregular-shaped particle, the fluidity of the adhesive during thermocompression bonding will be good, resulting in improved adhesion to the adherend interface and thermal conduction. This is because the sex is improved.
The shape of the filler is preferably a true sphere, but the shape is not limited to a true sphere, and a shape may be slightly distorted.

In the second aspect of the present invention, a functional group capable of reacting with a resin component can be added to the surface of the filler by coupling the surface of the filler. Therefore, a chemical bond is generated between the filler and the resin at the same time when the adhesive is cured, so that the cohesive force of the entire adhesive bulk after curing is increased.
As a result, it is possible to suppress the generation of microcracks that occur when the adhesive is cured. Further, by using an adhesive agent without microcracks for the LSI package, it is possible to prevent the intrusion of moisture into the inside and to obtain a highly reliable package.

As the coupling agent, glycidyl silane coupling agents such as γ-glycidoxypropyltrimethoxysilane and γ-glycidoxypropyltriethoxysilane, amine silane coupling agents, titanium coupling agents, etc. Is used. In particular, it is desirable to use a glycidyl silane coupling agent from the viewpoint of the storage stability of the adhesive. On the other hand, as fillers, fused silica (spherical, crushed type), crystalline silica, alumina, boron nitride, silicon nitride, magnesium oxide, diamond powder, insulating fillers such as silicon carbide, and silver, gold, copper, aluminum, etc. A conductive filler is used. In particular, when a glycidyl silane coupling agent is used, the effect of the present invention on fused silica and crystalline silica is remarkably exhibited. The mixing ratio of filler / coupling agent during the coupling treatment is 100: 0.3.
It is preferably about 100: 10 (weight ratio).

It is desirable that the filler added to the adhesive material has a number average particle diameter D50 of 3 to 30 μm and does not include particles less than 1 μm, or a 5% particle diameter D5 is 1 μm or more. By not including particles smaller than 1 μm,
This is because the fluidity of the adhesive during thermocompression bonding is improved. Further, it is desirable that the 80% diameter D80 of the filler is (D50 value + D50 value × 2) or less. This is because the irregularities on the surface of the adhesive become large and a gap is created between the adhesive and the interface of the adherend.

The addition amount of the filler is preferably 5 to 50 vol% of the total adhesive after curing. This is because if it is less than 5 vol%, there is no effect of addition, and if it exceeds 50 vol%, peeling occurs at the interface, and in any case, heat generation of the device cannot be efficiently conducted. Further, as a tackifier, synthetic C5 resin, hydrogenated hydrocarbon resin, polyterpene resin, polyterpene phenol resin, rosin ester resin, alkylallyl resin, alphamethylstyrene resin, coumarone indene resin, alkyl Allyl resin, alkyl aromatic polyindene resin, etc. are used.

As the epoxy resin which is a cross-linking agent, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin,
Epoxy compounds having two or more epoxy groups in one molecule, such as novolac type epoxy resin, silicon modified epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, biphenol type epoxy resin, alicyclic epoxy resin, and epoxidized polybutadiene Such as C = C
A polyepoxy compound obtained by oxidizing a compound having a double bond is used.

Also, by forming an adhesive sheet from the adhesive material of the present invention and using it for the adhesion, it is possible to obtain the same adhesion as in the precoat method. As a method for forming an adhesive sheet, a fluorine release sheet (eg, Tedler, manufactured by DuPont Co., Ltd.) is coated with an adhesive varnish using a screen or a stencil, and the solvent is scattered by preliminary drying,
There is a method of forming a sheet. After transferring the sheet to an adherend, the release sheet is peeled off and thermocompression bonded to another adherend, whereby the same adhesion as in the precoat method can be obtained.

As the auxiliary curing agent for the epoxy compound, a phenol-based cured product (phenol novolac, cresol novolac, etc.), an amine-based cured product (diamines), an acid anhydride, etc. may be used in combination. To precoat,
The viscosity of the adhesive is adjusted with a diluent. As the diluent, a solvent that can dissolve the reactive thermoplastic resin such as toluene, xylene, turpentine oil, and tetralin and other additive components is used.

If desired, the adhesive may be triphenylphosphine, imidazole or JP-A-5-182515.
There is no problem even if a curing accelerator such as an imidazole compound adduct described in JP-A No. 1993-242242 is added. The adhesive material forming the insulating layer is applied to the surface of the substrate by screen printing or the like, and the thickness of the insulating layer is determined by the mask thickness of the screen printing and the amount of non-volatile components in the adhesive material. The thickness of the insulating layer is involved in adhesiveness, electrical insulation, low stress when adhering different materials, and the like.
It is desirable that the thickness is 5 μm.

[0025]

Next, an embodiment of the present invention will be described. (Examples 1 and 2) Hydrogenated styrene-ethylene-butylene-styrene copolymer (Kreton G-165) was used as the main component.
(2, shell chemistry) was put into a three-necked flask together with toluene, a reflux ring was attached, and the toluene reflux temperature (about 11
The mixture was stirred at 4 ° C. for 30 minutes. The blending ratio of toluene is 8
It was set to 0 wt%. After dissolving the main agent, while continuing stirring, 20 parts by weight of cresol novolac type epoxy resin (N-660 Dainippon Ink and Chemicals, Inc.) per 100 parts by weight of the main agent and tackifier (Stevelite ester 10, Rika Hercules) as the main agent 100 parts by weight was added to 100 parts by weight, and stirring was continued until a uniform mixed state was obtained. After the varnish became uniform, it was immediately cooled to room temperature.

Next, with respect to the varnish, spherical alumina (AO-509, a product cut by less than 1 μm in diameter, Admatex) whose particle size distribution is shown in FIG. 3 and spherical alumina (AO-502, Admatex) having an average diameter of 0.7 μm are dried. It was added so that the filling amount afterwards would be 30 vol%, mixed by a roll, and a curing accelerator (Nova Cure H
X-3921, Asahi Kasei) to 100 parts by weight of the main agent,
An adhesive material was obtained by adding 10 parts by weight.

The following tests were conducted on the obtained adhesive material. (1) Adhesive strength The obtained adhesive material was applied to a copper plate (20 mm opening) in an area of 10 × 3 mm by screen printing (mask thickness 80 μm).
m), the applied adhesive material was dried at 80 ° C. for 20 minutes.

The copper-clad side of a 10 × 50 mm copper-clad printed board was pressure-bonded onto a dry adhesive material on a copper plate under the conditions of 90 ° C./1 MPa / 20 seconds, and further post-cured at 170 ° C./5 h. . A 90 ° peel strength test was performed on the adhesive samples. In addition, the pressure cooker tester (121 ° C / 1
The peel strength when moisture was absorbed at 00% RH / 48 h) was measured. (2) Thermal resistance A semiconductor device according to 200 was prototyped using the obtained adhesive material, and the thermal resistance of the semiconductor device was measured when the adhesive of the present invention was used as a die bonding agent.

Table 1 shows the adhesive material composition and the evaluation results for the above examples. (Comparative Examples 1 to 3) Hydrogenated styrene-ethylene-butylene-styrene copolymer (Kreton G-165) was used as the main agent.
(2, shell chemistry) was put into a three-necked flask together with toluene, a reflux ring was attached, and the toluene reflux temperature (about 11
The mixture was stirred at 4 ° C. for 30 minutes. The blending ratio of toluene is 8
It was set to 0 wt%. After dissolving the main agent, while continuing stirring, 20 parts by weight of cresol novolac type epoxy resin (N-660 Dainippon Ink and Chemicals, Inc.) per 100 parts by weight of the main agent and tackifier (Stevelite ester 10, Rika Hercules) as the main agent 100 parts by weight was added to 100 parts by weight, and stirring was continued until a uniform mixed state was obtained. After the varnish became uniform, it was immediately cooled to room temperature.

Next, an amorphous alumina having a spherical shape with respect to the varnish and a particle size distribution shown in Table 2 (AS-40, Showa Denko)
(Comparative Example 3) had a total filling amount of 30 after drying.
After adding so as to be vol%, they were mixed by a roll, and 10 parts by weight of a curing accelerator (Novacure HX-3921, Asahi Kasei) was added to 100 parts by weight of the main component just before the completion of kneading to obtain an adhesive material.

The obtained adhesive material was tested in the same manner as in the examples. Table 1 shows the adhesive material composition and the evaluation results for the comparative examples.

[0032]

[Table 1]

[0033]

[Table 2] (Example 3) Fused silica (FB-6S, manufactured by Denki Kagaku Co., Ltd.) and γ-glycidoxypropyltriethoxysilane were dry-blended with a high speed mixer at 100: 1 (weight ratio), and then the fused silica 2 at room temperature
After standing for 4 hours, the filler was subjected to coupling treatment.

Hydrogenated styrene / ethylene / butylene / styrene copolymer (clint G1652) 10 as a main agent
20 parts by weight of cresol novolac type epoxy resin (N660), 100 parts by weight of powdering agent (stevelite ester 40), and 80% by weight of toluene compounding ratio to 0 parts by weight.
The fused adhesive resin component was mixed with fused silica subjected to the coupling treatment to obtain an adhesive paste. The presence or absence of microcracks in the obtained cured adhesive was confirmed by SEM. There were no microcracks.

An LSI package using the above adhesive was produced, subjected to a moisture absorption treatment at 85 ° C./85% RH / 24 h, and then the popcorn crack of the adhesive layer after mounting on the mounting board was observed and the package about,
A pressure cooker test was performed when a bias was applied to evaluate the occurrence of short circuits between wirings. (Comparative Example 4) With respect to the adhesive in Example 3, a sample to which fused silica not subjected to the coupling treatment was added was prepared, and similarly, presence or absence of microcracks and popcorn cracks and occurrence of short circuit between wirings of the LSI package were evaluated. did. Microcracks were seen.

The results of inter-wiring sheet generation in Example 3 and Comparative Example 4 are shown in FIG. (Examples 4 to 5) The adhesive material of the present invention was used as a semiconductor element,
In a semiconductor device including a substrate on which the semiconductor element is mounted and a resin for sealing the semiconductor element, the semiconductor element and the substrate on which the semiconductor element is mounted are used as an adhesive material for the substrate and the wiring layer. In a semiconductor device including a resin for sealing the semiconductor element, a resin filling hole is formed in the substrate, and the resin is filled through the resin filling hole from a surface of the substrate different from a surface on which the semiconductor element is arranged. In the semiconductor device in which the semiconductor element is introduced by sealing the semiconductor element, a semiconductor device excellent in heat dissipation, adhesiveness, and workability can be obtained by using it as an adhesive material for a frame body and a wiring layer and a die bond material. You can get it. (See FIGS. 1 and 2)

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a semiconductor device according to the present invention.

FIG. 2 is an overall view of a semiconductor device according to the present invention.

FIG. 3 shows a particle size distribution of spherical alumina of an example.

FIG. 4 shows rates of occurrence of short circuits between wirings in Example 3 and Comparative Example 4.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Semiconductor element 2 ... Substrate 3 ... Resin 4 ... Outer lead 5 ... Frame 7a ... Upper lid 7b ... Lower lid 9 ... Insulating layer 10 ... Wire 14 ... Resin filling hole 15 ... Wiring layer 16 ... Conductive bonding material 18 ... die bonding layer 52 ... test pad portion 53 ... resin-filled recess 200 ... semiconductor device

Claims (5)

[Claims] 1. An adhesive material comprising a thermoplastic resin having a reactive functional group as a main ingredient and a tackifier, a cross-linking agent and a filler, wherein the filler has a smooth surface shape. Adhesive material. 2. An adhesive material containing a thermoplastic resin having a reactive functional group as a main component and a tackifier, a cross-linking agent and a filler, wherein the filler is previously subjected to a coupling treatment. Adhesive material to do. 3. The number average particle diameter D50 of the filler is 3 to
The adhesive material according to claim 1 or 2, which has a particle size of 30 μm and does not contain particles having a particle size of less than 1 μm or has a 5% particle size D5 of 1 μm or more. 4. A semiconductor device, wherein the adhesive material according to claim 1, 2 or 3 is used as an adhesive material between a substrate on which a semiconductor element is mounted and a wiring layer. 5. A semiconductor device, wherein the adhesive material according to claim 1, 2 or 3 is used as an adhesive material between a substrate on which a semiconductor element is mounted and the semiconductor element.