JPH11100564A - Adhesive based on polyamic acid and epoxy resin and method for manufacturing semiconductor device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a semiconductor device which is excellent in workability, can bond a chip and a metal frame with a high bonding force at a low temperature, and has high resistance to reflow cracks. SOLUTION: a) Polyamic acid 96-6 soluble in a solvent.
0 parts by weight, b) 3-39 parts by weight of epoxy resin and c)
1 to 20 parts by weight of a curing agent, and further, a chip is adhered to an adhesive containing a solvent and a metal frame using the adhesive, and the whole is resin-sealed. Manufacturing method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device in which a chip and a metal frame are bonded and then sealed with a resin, and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand for reliability of semiconductor devices such as ICs. On the other hand, as packages become thinner and smaller, mounting on a substrate by a so-called surface mounting method is performed, and the use of an infrared reflow furnace or the like makes the heat load on the semiconductor device more severe.
Under such circumstances, the phenomenon that water absorbed in the semiconductor device expands in the reflow furnace during mounting, peels off the sealing material and causes cracks in the semiconductor device (hereinafter, referred to as reflow crack) has become a problem. I have.

In an IC manufacturing process, a chip is bonded to a so-called die pad, which is a part of a lead frame, using an adhesive in order to hold and fix the chip (hereinafter, this process is referred to as die bonding). In a subsequent step, the silicon chip is electrically connected to the lead frame (a process of wire bonding). At this time, since the silicon chip is connected by a gold wire, the silicon chip is generally heated to a temperature close to 300 ° C.

As an adhesive for die bonding, an adhesive (die bonding material) such as a so-called silver paste in which a thermosetting epoxy resin is filled with a filler such as silver powder is widely used. These die bonding materials are widely used because they are liquid and easy to apply, and form an adhesive layer having excellent heat resistance in a short time.

However, epoxy resin-based die bonding materials generate a large amount of volatile substances such as diluents and pyrolysis gases, and consequently contaminate the surroundings of the chip, deteriorating the adhesion with the sealing material, There is a problem that the agent easily absorbs water and easily causes reflow cracks. In particular, when the size of the chip used is large, reflow cracks are more likely to occur due to an increase in water absorption and an increase in stress accompanying curing shrinkage.

On the other hand, aromatic polyimides are used in various forms in semiconductor devices because of their excellent heat resistance and electrical characteristics. Have also been studied in various ways. However, since aromatic polyimides with high heat resistance do not dissolve in general-purpose solvents, they are applied to the adhesive surface in the form of polyamic acid and imidized over a long period of time. In addition, the process becomes complicated, such as bonding to a lead frame, resulting in poor productivity. In addition, a very high processing temperature exceeding the temperature in the wire bonding process is required. There is a problem.
In addition, when polyamic acid is used as an adhesive, the adhesive strength to metal is generally inferior to epoxy resin and the like.

[0007]

SUMMARY OF THE INVENTION The present invention according to claim 1 or 2 provides an adhesive which is excellent in workability and can bond a chip and a metal frame at a low temperature with a high adhesive strength. The third aspect of the present invention provides a method for manufacturing a semiconductor device having high resistance to reflow cracks.

[0008]

The present invention comprises: a) 96 to 60 parts by weight of a polyamic acid soluble in a solvent; b) 3 to 39 parts by weight of an epoxy resin; and c) 1 to 20 parts by weight of a curing agent. And an adhesive further containing a solvent.

According to the present invention, there is also provided a polyamic acid comprising: a) a compound represented by the following general formula (I):

Embedded image (However, in the general formula (I), n represents an integer of 4 to 12) 40 to 95 mol% of tetracarboxylic dianhydride, b) the following general formula (II)

Embedded image (Wherein, n represents an integer of 4 to 12 in the general formula (II)) 5 to 20 mol% of an aliphatic dicarboxylic acid shown in c) and a carboxylic acid component comprising 0 to 55 mol% of other carboxylic anhydrides And d) the above adhesive obtained by reacting a diamine component.

[0010] The present invention also relates to a method of manufacturing a semiconductor device, comprising bonding a chip on a metal frame using any one of the above adhesives and sealing the whole with a resin.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Examples of the tetracarboxylic dianhydride represented by the general formula (I) include hexamethylene bis trimellitate dianhydride, decamethylene bis trimellitate dianhydride, dodecamethylene bis trimellitate dianhydride and the like. There is. -By using the tetracarboxylic dianhydride represented by the general formula (I), the glass transition temperature can be lowered without impairing the heat resistance of the polyamic acid.
For this purpose, it is preferable to use at least 40 mol% of the acid component of the polyamic acid. Since it is necessary to use the dicarboxylic acid represented by the general formula (II) from the viewpoint of solvent solubility and low melt viscosity, it is preferable to use the dicarboxylic acid in an acid component at 95 mol% or less, and to use 60 to 92 mol%. More preferably,

The dicarboxylic acids represented by the general formula (II) include adipic acid, sebacic acid, dodecane-2 acid and the like. Further, the aliphatic dicarboxylic acid represented by the general formula (II) can improve the solubility of polyamic acid in a solvent and lower the glass transition temperature. Further, it is possible to lower the melt viscosity of the polyamic acid by copolymerizing the aliphatic dicarboxylic acid. Aliphatic dicarboxylic acids are
It is preferable to use 5 to 20 mol% of the acid component,
It is more preferable to use 15 mol%. If the amount of the aliphatic dicarboxylic acid is too small, the solubility in the solvent is insufficiently improved. If the amount is too large, the heat resistance of the polyamic acid resin is reduced, and when heated to a high temperature, a decomposition gas is generated to lower the reflow crack resistance.

Other acid components are 3,3 ', 4,4'
-Tetracarboxybenzophenone dianhydride, bis (3,4-dicarboxyphenyl) dimethylsilane dianhydride, 1,2,3,4-butanetetracarboxylic dianhydride, bis (exo-bicyclo [2,2, 1] heptane
2,3-dicarboxylic acid) sulfone dianhydride, 2,2-bis (3,4-dicarboxyphenoxyphenyl) hexafluoropropane dianhydride, 1,3-bis (2-hydroxyhexafluoroisopropyl) benzenebis ( Trimellitic dianhydride), pyromellitic dianhydride, 3,
3 ', 4,4'-biphenyltetracarboxylic dianhydride, 2,3,3', 4'-benzophenonetetracarboxylic dianhydride, 2,3,6,7-tetracarboxynaphthalene dianhydride, , 2'-bis (3,4-dicarboxyphenyl) propane dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, benzene-1,2,2
3,4-tetracarboxylic dianhydride, 2,6-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, pyrrolidine-2,3,4,5-tetracarboxylic dianhydride And the like. These are preferably used in the range of 0 to 55 mol% in the acid component,
More preferably, it is used in an amount of 2 mol% or less.

As the diamine component, o-phenylenediamine, m-xylylenediamine, 3,3'-diaminodiphenyl ether, 3,3'-diaminodiphenyldifluoromethane, 3,3'-diaminodiphenylmethane, 3,3'- Diaminodiphenyl sulfone, 3,3 '
-Diaminodiphenyl ketone, 2,2-bis (3-aminophenyl) propane, 2,2-bis (4- (4-aminophenoxy) phenyl) propane, 2,2-bis (3
-Aminophenyl) hexafluoropropane, 1,1-
Aromatic diamines such as bis (4- (4-aminophenoxy) phenyl) cyclohexane and isomers thereof,
Examples include aliphatic diaminoalkanes such as 6-diaminohexane and 1,12-diaminododecane.

As a raw material actually used for the synthesis of polyamic acid, a lower alcohol ester or an acid halide derived from an acid component may be used, or a lower carboxylic acid capable of deriving a corresponding amine as an amine component. Amides and the like may be used. As a method for synthesizing the polyamic acid, the polyamic acid can be synthesized by reacting the acid component and the diamine component at 5 to 40 ° C. in a solvent capable of dissolving the polyamic acid. As a method for adding the aliphatic dicarboxylic acid, a polyamide having an amino terminal may be synthesized by reacting an aliphatic dicarboxylic acid and a diamine in excess of a diamine in advance, and this may be used.

The aromatic polyamic acid used in the present invention has a glass transition temperature of a polyimide resin obtained by heating the aromatic polyamic acid.
g Colorimeter (DSC) at a heating rate of 10 ° C./min, preferably 80 ° C. to 200 ° C., more preferably 80 ° C. to 150 ° C. If the glass transition temperature is too low, the adhesive strength at high temperatures becomes insufficient, water absorption increases, and reflow cracks easily occur.If the glass transition temperature is too high, the epoxy resin cures during bonding and the resin coatability increases. Adhesive strength tends to decrease due to decrease.

As a method for obtaining the adhesive, a solution of the polyamic acid obtained at the time of synthesis may be used as it is as an adhesive, and the solution of the polyamic acid obtained at the time of synthesis may be used as a poor solvent for the polyamic acid, such as methanol. And the polyamic acid may be isolated and dissolved again.

The epoxy resin used in the present invention is not particularly limited as long as it is a compound having two or more epoxy groups in one molecule. For example, a phenol novolak type epoxy resin [N-730S (Dainippon Ink Chemicals, Inc.) Industry
(Trade name), Quatrex-2010 (trade name of Dow Chemical Company)], cresol novolak type epoxy resin [Y
DCN-702 (trade name of Toto Kasei Kogyo Co., Ltd.), EOCN
-100 (trade name of Nippon Kayaku Co., Ltd.), bisphenol A type epoxy resin [AER-X8501 (trade name of Asahi Kasei Kogyo Co., Ltd.), Epicoat 828, YL-980 (all of these are Yuka Shell Epoxy Co., Ltd.) ) Trade name)], bisphenol F type epoxy resin [YDF-170 (Toto Kasei Co., Ltd. trade name)], bisphenol AD type epoxy resin [R-1710 (Mitsui Petrochemical Industry Co., Ltd. trade name)],
Multifunctional epoxy resin [EPPN-501 (Nippon Kayaku Co., Ltd.)
Trade name), TACTIX-742 (trade name of Dow Chemical Company), VG-3010 (trade name of Mitsui Petrochemical Industry Co., Ltd.), 1032S (trade name of Yuka Shell Epoxy Co., Ltd.), epoxy having a naphthalene skeleton Resin [HP-
4032 (trade name of Dainippon Ink and Chemicals, Inc.)], alicyclic epoxy resin [EHPE-3150 (trade name of Daicel Chemical Industries, Ltd.)], amine type epoxy resin [ELM-1]
00 (trade name of Sumitomo Chemical Co., Ltd.), YH-434L (trade name of Toto Kasei Co., Ltd.), resorcinol type epoxy resin [Denacol EX-201 (trade name of Nagase Kasei Kogyo Co., Ltd.)]
Neopentyl glycol type epoxy resin [Denacol E
X-212 (trade name of Nagase Kasei Kogyo Co., Ltd.), ethylene
Propylene glycol type epoxy resin [Denacol EX
−810, 811, 850, 851, 821, 830,
832, 841, 861 (trade name of Nagase Kasei Kogyo Co., Ltd.), an epoxy resin represented by the following formula (III) [E
-XL-24, E-XL-3L (trade name of Mitsui Toatsu Chemicals, Inc.), etc. These epoxy resins may be used in an appropriate combination.

[0019]

Embedded image (Where n is an integer of 0 to 5)

As the curing agent, a phenol novolak type resin, a cresol novolak type resin, an imidazole derivative such as dicyandiamide, imidazole or 2-ethyl-4-methyl-imidazole can be used.
Further, as a curing accelerator, triarylphosphine such as triphenylphosphine, tricycloalkylphosphine such as tricyclohexylphosphine, tributylphosphine, and tertiary phosphine compound such as trialkylphosphine such as trioctylphosphine; A quaternary phosphonium salt such as tetraphenylphosphinetetraphenylborate may be contained. For the purpose of improving the adhesive strength of the adhesive at room temperature, commonly used additives such as a silane coupling agent, a titanium coupling agent, and a metal acetylacetone complex may be added.

Examples of the solvent used in the adhesive of the present invention include N-methylpyrrolidone, dimethylacetamide, dimethylsulfoxide, dioxane, diglyme and the like. If it is a solvent that can be
There is no particular limitation. In particular, the above-mentioned polyamic acid X is
Cyclohexanone, xylene, tetrahydrofuran (T
Since it can be dissolved in general-purpose solvents such as HF), the effect on the environment and workers can be reduced, and the solvent solubility of polyamic acid is excellent, the solid content can be increased, and the drying time of the adhesive can be shortened. Can provide higher productivity.

The polyamic acid, the epoxy resin and the curing agent comprise 96 to 60 parts by weight, preferably 95 to 80 parts by weight of a polyamic acid soluble in a solvent, 3 to 39 parts by weight, preferably 5 to 20 parts by weight of an epoxy resin. 1 to 20 parts by weight of a curing agent, preferably 2 to 10 parts by weight, and 0 to 3 of a curing accelerator
It is blended so as to be 1 part by weight, preferably 1 to 2 parts by weight. If the amount of the polyamic acid is too large, the adhesive strength is inferior. If the amount is too small, the adhesive after adhesion and drying becomes brittle, and the reflow crack resistance decreases. If the amount of the epoxy resin is too large, the adhesive after adhesion and drying becomes brittle, the water absorption increases, and the reflow crack resistance decreases. If the amount of the epoxy resin is too small, the adhesive strength decreases. Too much curing agent will result in excess,
An increase in water absorption and a decrease in adhesive strength are likely to occur.If the amount of the curing agent is too small, the curing of the epoxy resin becomes insufficient,
Heat resistance decreases.

The curing accelerator is preferably used in order to completely promote the reaction of the epoxy resin at the time of bonding and to enhance the adhesive strength. However, if it is too much, the stability of the adhesive at room temperature tends to be reduced. Is used in an amount of 0 to 3 parts by weight, more preferably 1 to 2 parts by weight. The polyamic acid, the epoxy resin, the curing agent, and the curing accelerator used as needed are used so that the total amount becomes 100 parts by weight in the above composition. These components are preferably used after being dissolved in a solvent.
It is preferable to use 50 to 400 parts by weight based on parts by weight.

The adhesive of the present invention is applied to a bonding surface of a silicon wafer or a metal frame in advance, and a solvent is evaporated to form an adhesive coating film. You can do it. Further, by dispensing the adhesive on the metal frame as in the case of the silver paste and providing a heating step for evaporating the solvent before the die bonding step, productivity equal to or higher than that of the silver paste can be realized.

The metal frame used in the semiconductor device in the present invention is more preferably a tab-shaped frame having a small bonding area and a part of the chip exposed on the back side of the metal frame. Specific tab shapes are illustrated in FIGS. 1, 2, and 3. FIGS. 1, 2, and 3 are plan views each showing an example of the tab shape of the metal frame. The metal frame must be shaped so that the chip can be sucked from the lower surface of the metal frame to prevent the chip from moving due to heating during the wire bonding process, or that the chip can be fixed by holding the chip from the upper surface of the chip with the metal frame Is preferred. In general, the adhesive strength between the chip and the sealing resin is preferably higher than that of the metal frame and the sealing material since the reflow crack due to the expansion of water can be suppressed when the chip back surface is exposed. Also, by minimizing the bonding area to the minimum necessary for obtaining the bonding strength, the adhesive which easily absorbs water and the bonding portion where stress is concentrated are reduced, and the reflow crack resistance is improved.

[0026]

The present invention will be described below in detail with reference to examples. Synthesis Example 1 (Synthesis of Polyamide) 180.0 g of water-free N-methylpyrrolidone and 120.0 g of xylene were put into a reactor equipped with a heating / cooling device, a stirrer, and a reflux device.
123.0 g of 2-bis (4- (4-aminophenoxy) phenyl) propane (hereinafter referred to as BAPP) and 40.4 g of sebacic acid were added. This was heated to 100 ° C. and reacted for 2 hours, further heated to 160 ° C. and reacted for 3 hours while keeping the reflux device at 120 ° C. to obtain a polyamide solution. The solid content of the solution was 50% by weight, and the amino group equivalent of the polyamide calculated from the amount of amino groups in the solution and the solid content was 800 g / eq.

Synthesis Example 2 (Synthesis of Polyamic Acid a) 441.2 g of water-free N-methylpyrrolidone was placed in a reactor equipped with a heating / cooling device, a stirrer and a reflux device, and 34.9 g of dried BAPP was added thereto. After dissolution, the polyamide solution 16.09 synthesized in Synthesis Example 1 was added thereto. Further, 47.0 g of dried decamethylene bistrimellitate dianhydride (hereinafter referred to as DBTA) was added thereto while cooling the reactor to 20 ° C. or lower, and reacted for 4 hours to obtain a polyamic acid solution. This polyamic acid solution is heated to 120 ° C.
The glass transition temperature of the polyimide obtained by heating at 180 ° C for 3 hours and then at 300 ° C for 2 hours was 118 hours.
° C.

Synthesis Example 3 (Synthesis of Polyamic Acid b) 502.6 g of N-methylpyrrolidone N-methylpyrrolidone containing no water was placed in a reactor equipped with a heating / cooling device, a stirrer and a reflux device, and dried. 24.8 g of 3,3'-diaminodiphenylsulfone was dissolved, and the polyamide solution 16.09 synthesized in Synthesis Example 1 was added thereto. Further, 31.0 g of dried 2,3,3 ', 4'-tetracarboxydiphenyl ether was added to the reactor while cooling the reactor to 20 ° C or lower, and reacted for 4 hours to obtain a polyamic acid solution. The glass transition temperature of the polyimide obtained by heating this polyamic acid solution in the same manner as in Synthesis Example 2 was 242.
° C.

Synthesis Example 4 (Synthesis of Polyamic Acid c) 370.0 g of water-free cyclohexanone was placed in a reactor equipped with a heating and cooling device, a stirrer and a reflux device, and 41.0 g of dried BAPP was dissolved therein. To this, 16.0 g of the polyamide solution synthesized in Synthesis Example 1 was added.
Further, 52.2 g of dried DBTA was added thereto while cooling the reactor to 20 ° C. or lower, and reacted for 4 hours to obtain a polyamic acid solution. The glass transition temperature of the polyimide obtained by heating this polyamic acid solution in the same manner as in Synthesis Example 2 was 122.
° C.

Examples 1 to 3 and Comparative Examples 1 to 3 Each component was mixed in the composition shown in Table 1 to prepare an adhesive. Each adhesive was applied to a metal frame having the shape shown in FIG. 1 using a dispenser. Next, the metal frame was heated on a heating stage at 200 ° C. for 20 seconds to evaporate the solvent in the adhesive, and then the metal frame was placed on a heating stage heated to 280 ° C. in a die bonding apparatus. A 5 mm square chip was placed on the chip, and a load of 130 g was applied for 10 seconds to bond the chip. At this time, contamination of the heating stage was examined. At this time, those with no adhesion of the resin on the heating stage were evaluated as ○. Contamination of the heating stage causes non-uniform heating, induces contamination of the frame, and lowers reflow crack resistance.

Further, with respect to the obtained metal frame and chip joint, a load was applied to the exposed portion of the chip from the back side of the frame using a tension gauge, and the peel adhesion at room temperature was evaluated. Table 1 shows the results. If the adhesive strength at room temperature is 100 gf / chip or less, the chip may peel off during movement. Subsequently, the metal frame and the chip joined product were resin-sealed with a transfer molding device to manufacture a semiconductor device. CEL manufactured by Hitachi Chemical Co., Ltd. as a sealing material
-9200 was used. In order to evaluate the reflow crack resistance, the manufactured semiconductor device was absorbed at 85 ° C. and a humidity of 85%, and treated at 240 ° C. for 10 seconds in an infrared reflow furnace. The time during which swelling or cracking occurred in 10% or more of the semiconductor device was measured as the anti-reflow time. Table 1 shows the results.
Shown in In Table 1, HP-850N is phenol novolak resin (manufactured by Hitachi Chemical Co., Ltd.), 2E4MZ is 2-ethyl-4-methyl-imidazole, and TPPK is tetraphenylphosphonium tetraphenylborate.

[0032]

[Table 1]

[0033]

The adhesive according to claim 1 or 2 can adhere the chip and the metal frame with a high adhesive strength.
Excellent reflow crack resistance when sealed with resin. According to the method of claim 3, a semiconductor device can be manufactured with high productivity.

[Brief description of the drawings]

FIG. 1 is a plan view showing an example of a tab shape of a metal frame.

FIG. 2 is a plan view showing another example of the tab shape of the metal frame.

FIG. 3 is a plan view showing another example of the tab shape of the metal frame.

[Explanation of symbols]

 1 Metal frame 2 Chip

Claims (3)

[Claims] 1. A) Polyamic acid 96 to 6 soluble in a solvent
0 parts by weight, b) 3-39 parts by weight of epoxy resin and c)
An adhesive comprising 1 to 20 parts by weight of a curing agent and further containing a solvent. 2. The polyamic acid is a) having the following general formula (I): (Where n is an integer of 4 to 12 in the general formula (I)) 40 to 95 mol% of tetracarboxylic dianhydride, b) the following general formula (II) (Wherein, n represents an integer of 4 to 12 in the general formula (II)) 5 to 20 mol% of an aliphatic dicarboxylic acid shown in c) and a carboxylic acid component comprising 0 to 55 mol% of other carboxylic anhydrides And d) reacting the diamine component to obtain the adhesive according to claim 1. 3. A method for manufacturing a semiconductor device, comprising: bonding a chip onto a metal frame using the adhesive according to claim 1; and sealing the whole with a resin.