JP2002105428A - Adhesive film for die bond and semiconductor device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an adhesive film for die bond which can form readily a uniform adhesive layer on an electrode member, fix at a low temperature such as an ordinary temperature and maintain easily quality. SOLUTION: An adhesive film for a die bond comprises a polycarbodiimide copolymer represented by the following formula (wherein k is an integer of 0 to 30; m is an integer of 2 to 100; n is an integer of 0 to 30; R1 is a 2-10C alkylene group; R2 is an aromatic diisocyanate residue; and R3 is an aromatic monoisocyanate residue).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an adhesive film for die bonding, which is a material for fixing a semiconductor chip and an electrode member. The present invention also relates to a semiconductor device using the film.

[0002]

2. Description of the Related Art Conventionally, in a process of manufacturing a semiconductor device, a semiconductor chip is fixed to a lead frame or an electrode member by a conventional method.
Silver paste is used. Such a fixing process is performed by
A paste is applied on a die frame die pad or the like, a semiconductor chip is mounted on the paste, and the paste layer is cured.

[0003] However, as a result of large variations in the coating amount and the coating shape due to the viscosity behavior and deterioration of the paste, the formed paste thickness is not uniform and the bonding strength of the semiconductor chip is unreliable. poor. That is, if the amount of paste applied is insufficient and the bonding strength between the semiconductor chip and the electrode member is low, the semiconductor chip peels in the subsequent wire bonding step. On the other hand, if the coating amount of the paste is too large, the paste is cast over the semiconductor chip, causing poor characteristics, and the yield and reliability are reduced. Such a problem in the fixing process has become particularly remarkable as the size of the semiconductor chip increases. Therefore, it is necessary to frequently control the amount of paste applied, which often impairs workability and productivity.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a semiconductor chip and an electrode member with a stable bonding strength with no variation in the coating amount and a workability and productivity during coating. An object of the present invention is to provide an excellent adhesive film for die bonding. The present inventors have conducted various studies on such problems, and as a result, obtained the knowledge that the above problems can be solved by using a specific polycarbodiimide film, and completed the present invention.

When the adhesive film for die bonding of the present invention is used, an excellent adhesive layer having a uniform thickness and the like can be formed on an electrode member, and the above problem can be solved. Further, the semiconductor chip can be fixed at a low temperature and can withstand subsequent processing such as wire bonding connection and resin mold sealing.

[0006]

According to the present invention, there is provided the following formula:

[0007]

Embedded image(Where k is an integer of 0 to 30, m is an integer of 2 to 100,
n is an integer of 0 to 30, R ₁Is alkylene having 2 to 10 carbon atoms
Group, R₂Is an aromatic diisocyanate residue, R₃Is aromatic
A group monoisocyanate residue is meant. )
Adhesive die for die bonding consisting of recarbodiimide copolymer
Film. Is provided.

[0008]

DETAILED DESCRIPTION OF THE INVENTION Next, the polycarbodiimide copolymer used in the adhesive film for die bonding of the present invention and a method for producing the same will be described. To prepare the polycarbodiimide of the formula (I), the following formula (II):

[0009]

Embedded image (In the formula, m is an integer of 2 to 100, and R ₁ has 2 to 10 carbon atoms.
Means an alkylene group. ) Is reacted with an aromatic diisocyanate to obtain a polyurethane. Then, in the presence of a carbodiimidization catalyst, it is preferable to carry out carbodiimidation with a terminal isocyanate group and an aromatic diisocyanate, and to block the end with an aromatic monoisocyanate to obtain a polycarbodiimide copolymer.

That is, 2 moles or more, preferably 4 to 80 moles per mole of the polycarbonate of the formula (II).
Times, more preferably 5 to 50 times by mole of aromatic diisocyanate, usually in the presence of a solvent, usually at 0 to 120 ° C,
The reaction is preferably performed at 20 to 100 ° C. for about 1 minute to 5 hours. The point that almost no hydroxyl group was present in the system
This is the end point of the reaction for producing the CO-containing polyurethane.

Then, in the presence of a carbodiimidation catalyst,
The polyurethane and the aromatic diisocyanate present in the system in excess are usually at 40 to 150 ° C, preferably at 50 to 150 ° C.
The reaction is carried out at 140 ° C. to obtain the copolymer of the formula (I).

Here, the required aromatic diisocyanate is at least twice the mole of 1 mole of the above-mentioned polycarbonate, and may be added at this reaction stage. There may be. In addition, terminal blocking by aromatic monoisocyanate is carried out at the beginning of carbodiimidation,
It is preferred to add aromatic monoisocyanate during the middle stage, end stage or overall.

[0013] The end point of the reaction, the absorption derived from the carbodiimide group by IR measurement can be confirmed by the disappearance of absorption attributable to preparative groups ^{(2280cm -1) - (2140cm -} 1) observation and isocyanate.

(Polycarbonatediol) In the formula (II), R ₁ is an alkylene group having 2 to 10 carbon atoms, and examples thereof include ethylene, tetramethylene, hexamethylene, and octamethylene. Also, m is 2 to 10
It is an integer of 0, preferably 5 to 80.

Polycarbonate todiol is carbonate
Polycarbonate diols containing a thiol group may be used. Specific examples include polyethylene carbonate diols, polytetramethylene carbonate diols, and polyhexamethylene carbonate diols. , Polyoctamethylene carbonate
Toditol, polydodecamethylene carbonate and the like can be mentioned, and polyhexamethylene carbonate todiol is particularly preferred. These polycarbonate diols may be used alone or in combination of two or more.

(Aromatic diisocyanate) In the formula (II), R ₂
Is an aromatic diisocyanate residue, and R ₂ is
For example, tolylene diisocyanate residue, diphenylmethane diisocyanate residue and the like can be mentioned. Also,
k is an integer of 0 to 30, and preferably 2 to 20. N is an integer of 0 to 30, preferably 2 to 30.
20.

Therefore, the aromatic diisocyanate is
Specifically, 4,4'-diphenylmethane diisocyanate, 2,6-tolylene diisocyanate, 2,4-tolylene diisocyanate, 1-methoxyphenyl-2,4
-Diisocyanate, 3,3'-dimethoxy-4,4'-
Diphenylmethane diisocyanate, 4,4'-diphenyl ether diisocyanate, 3,3'-dimethyl-
4,4'-diphenyl ether diisocyanate, 2,2
-Bis [4- (4-isocyanate-tophenoxy) phenyl]
Hexafluoropropane, 2,2-bis [4- (4-isocyanate-tophenoxy) phenyl] propane and the like can be mentioned, and tolylene diisocyanate can be particularly preferably used. These diisocyanates may be used alone or in combination of two or more.

(Aromatic Monoisocyanate) Also, during any one of the last, middle and early stages of the polymerization reaction, or the whole, an aromatic monoisocyanate having an R ₃ group in the molecule is added to perform a terminal blocking treatment. Is preferred. Aromatic monoisocyanate used for such terminal blocking treatment
Specifically, phenyl isocyanate, p
-Nitrophenyl isocyanate, p- and m-tolyl isocyanate, p-formylphenyl isocyanate
And p-isopropylphenyl isocyanate. Particularly, p-isopropylphenyl isocyanate is preferably used. The polycarbodiimide copolymer solution whose terminal is blocked in this way has excellent storage stability of the solution.

(Reaction) The polymerization temperature is preferably from 40 to 150 ° C, more preferably from 50 to 140 ° C. Reaction temperature 40
If the temperature is lower than ℃, the reaction time becomes too long and is not practical. If the reaction temperature exceeds 150 ° C., it is difficult to select a solvent.

The concentration of diisocyanate monomer in the reaction solution is 5 to 80% by weight (hereinafter simply referred to as%). If the concentration is lower than 5%, the carbodiimidization reaction may not proceed. If it exceeds 80%, the control of the reaction may be difficult.

The solvent used for producing the polycarbodiimide and the organic solvent used for the polycarbodiimide solution may be those conventionally known. Specifically, halogenated hydrocarbons such as tetrachloroethylene, 1,2-dichloroethane and chloroform; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; cyclic ether solvents such as tetrahydrofuran and dioxane; toluene, xylene And other aromatic hydrocarbon solvents. These solvents may be used alone or as a mixture of two or more.

As the catalyst used for the carbodiimidization, any of the known phosphorus catalysts is suitably used. For example, 1-phenyl-2-phospholene-1-oxide, 3
-Methyl-2-phospholene-1-oxide, 1-ethyl-2-phospholene-1-oxide, 3-methyl-1-phenyl-2-phospholene-1-oxide, or phosphodies such as 3-phospholene isomers thereof And lenoxide.

After the completion of the copolymerization reaction, the reaction solution is poured into a poor solvent such as methanol, ethanol, isopropyl alcohol or hexane to precipitate a polycarbodiimide copolymer as a precipitate. Or the catalyst may be removed.

In order to prepare a polycarbodiimide solution, a polymer precipitated as a precipitate is washed and dried by a predetermined operation, and is dissolved again in an organic solvent. By performing such an operation, the solution stability of the polycarbodiimide copolymer can be improved.

Further, by-products contained in the polymer solution may be purified by adsorbing them on a suitable adsorbent or the like. As an adsorbent, for example, alumina gel, silica gel, activated carbon,
Zeolites, activated magnesium oxide, activated bauxite, flourace, activated clay, molecular sieve carbon and the like can be used alone or in combination.

The average degree of polymerization of the polycarbodiimide copolymer of the present invention is from 2 to 160, preferably from 9 to 120.
If the degree of polymerization of the polycarbodiimide copolymer is higher than this, gelation easily occurs within several minutes to several hours even at room temperature, which is not practically preferable. On the other hand, if the degree of polymerization is smaller than the above range, the reliability of the film is poor, which is not preferable.

(Production of Adhesive Film) In order to produce the adhesive film for die bonding of the present invention, a polycarbodiimide copolymer varnish is prepared by a known method (casting, spin coating, roll coating, etc.). The film is formed to an appropriate thickness. The formed film is usually dried at a temperature required for removing the solvent. That is, the coating temperature is, for example, 20 to 3 so that the curing reaction is dried without progressing much.
50 ° C., preferably 50-250 ° C., most preferably 7
0-200 ° C. If the drying temperature is lower than 20 ° C., the solvent remains in the film, and the reliability of the film becomes poor, which is not preferable. When the drying temperature is higher than 350 ° C.,
Thermal curing of the film is easy to proceed.

In producing the adhesive film of the present invention, a fine inorganic filler may be blended as long as the processability and heat resistance are not impaired. Various additives such as a smoothing agent, a leveling agent, and a defoaming agent for improving surface smoothness may be added as necessary. These blending amounts are based on the copolymer 1
The amount is 0.1 to 100 parts by weight, preferably 0.2 to 50 parts by weight based on 00 parts by weight.

The thickness of the adhesive film of the present invention is generally from 1 to 200 μm. Further, the shape and size of the sheet may be appropriately changed according to the adherend such as a lead frame or a semiconductor chip.

Further, in order to improve the adhesive strength, various additives such as a silane coupling agent, a titanium coupling agent, a nonionic surfactant, a fluorine surfactant, and a silicone additive are required for the adhesive film. May be added according to

In the production of the adhesive film, for example, aluminum, copper, silver, gold, nickel, chromium, lead, tin, zinc, palladium, etc. in order to impart conductivity, improve thermal conductivity, and adjust the elastic modulus. One or two or more of various inorganic powders composed of metals such as solder, alloys, ceramics such as alumina, silica, magnesia and silicon nitride, and other carbons may be added as necessary.

Further, these films may be used as a laminated adhesive sheet provided on a support. In order to manufacture such a laminated adhesive sheet, a varnish of the polycarbodiimide may be applied on a support, or a film may be formed in advance, and the film may be applied to the support by pressing or the like. -You may choose.

The support used here is a metal foil,
Insulating films and the like can be mentioned. As the metal foil, any of aluminum, copper, silver, gold, nickel, indium, chromium, lead, tin, zinc, palladium and the like may be used, and these may be used alone or as an alloy. As the insulating film, any film having heat resistance and chemical resistance, such as polyimide, polyester, and polyethylene terephthalate, can be used.

The above-mentioned metal foil and insulating film may be used alone, or two or more layers may be laminated.
For example, a two-layer substrate such as a metal foil / insulating film may be used. Examples of such a two-layer substrate include a copper / polyimide two-layer substrate.

Next, a bonding method using the adhesive film for die bonding of the present invention will be described. The adhesive film for die bonding of the present invention is preferably a long wound ribbon such as a reel. This is cut into predetermined dimensions (length, shape, etc.) by an appropriate means such as a cutter, and an adhesive layer having excellent uniformity in thickness, amount, etc. is supplied.

The cut piece thus formed is temporarily bonded to an electrode member, for example, a die pad of a lead frame, and a semiconductor chip is mounted thereon and heated.

For the heat treatment, known appropriate means such as a heater, an ultrasonic wave, and an ultraviolet ray may be used. The heating temperature is usually 50 to 300C, preferably 100 to 250C, and the heating time is 1 second to 30 minutes, preferably 1 second to 3 minutes. By such heating, the polycarbodiimide copolymer in the adhesive layer is cured, and the semiconductor chip and the electrode member are fixed.

As another method, first, the bonding film is fixed on a dicing apparatus, and one surface of the silicon wafer is temporarily bonded to the bonding film at room temperature to 90 ° C. and fixed. Next, the silicon wafer to which the bonding film has been temporarily bonded is cut by a dicing apparatus to obtain a semiconductor chip holding the adhesive. In this manner, the semiconductor chip to which the adhesive has been temporarily bonded is placed on an electrode member, for example, a die pad of a lead frame and heated. Note that the heat treatment can be performed under the same means and processing conditions as described above.

[0039]

Next, the present invention will be described more specifically with reference to examples and comparative examples. All syntheses were performed under a stream of nitrogen. In addition, the characteristic of the obtained polycarbodiimide was measured as follows.

The present invention is further embodied by Examples and Comparative Examples.
Explain physically. All syntheses were performed under a stream of nitrogen. What
The properties of the obtained polycarbodiimide are as follows.
Measured.IR  It measured using FT / IR-230 (made by JEOL).Number average molecular weight  HLC8120 (manufactured by Toso Co., Ltd.) as an apparatus, and G
MH_HR-H+ GMH_{H RH}+ G2000H
_HR(Toso Co., Ltd.) to develop tetrahydrofuran
The measurement was performed using the solvent.

[Production Example 1] (Production of polycarbodiimide) Tolylene diisocyanate was placed in a 500 mL four-necked flask equipped with a stirrer, a dropping funnel, a reflux condenser, and a thermometer.
(100 g, 0.57 mol) (Takenate 80 manufactured by Takeda Pharmaceutical Co., Ltd.), polyhexamethylene carbonate
(100 g, 0.10 mol) (UH-C manufactured by Ube Industries, Ltd.)
ARB100), xylene 75 g, cyclohexanone 2
5 g was charged and urethanization was performed at 100 ° C. for 3 hours.

After returning the solution to room temperature, the carbodiimidation catalyst (3-methyl-1-phenyl-2-phospholene-1) was used.
-Oxide) (0.883 g, 4.59 mmol), p-isopropylphenyl isocyanate (6.4793 g, 40.
2 mmol) and stirred at 100 ° C. for 2 hours to carry out polymerization. Carbodiimidization was confirmed by IR spectrum. The number average molecular weight (Mn) of this polycarbodiimide copolymer was 6,300.

[Production Example 2] (Production of polycarbodiimide) Tolylene diisocyanate was placed in a 500 mL four-necked flask equipped with a stirrer, a dropping funnel, a reflux condenser, and a thermometer.
(100 g, 0.57 mol) (Takenate 80 manufactured by Takeda Pharmaceutical Co., Ltd.), polyhexamethylene carbonate
UH-CARB200 (100 g, 0.05 mol) (UH-CARB200 manufactured by Ube Industries, Ltd.), xylene 75
g, and 25 g of cyclohexanone, and urethanized at 100 ° C. for 3 hours.

After returning the solution to room temperature, the carbodiimidation catalyst (3-methyl-1-phenyl-2-phospholene-1) was used.
-Oxide) (0.883 g, 4.59 mmol), p-isopropylphenyl isocyanate (6.4793 g, 40.
2 mmol) and stirred at 100 ° C. for 1 hour to carry out polymerization. Carbodiimidization was confirmed by IR spectrum. The number average molecular weight of this polycarbodiimide (M
n) was 6000.

[Production Example 3] (Production of polycarbodiimide) Tolylene diisocyanate was placed in a 500 mL four-necked flask equipped with a stirrer, a dropping funnel, a reflux condenser, and a thermometer.
(100 g, 0.57 mol) (Takenate 80 manufactured by Takeda Pharmaceutical Co., Ltd.), polyhexamethylene carbonate
(100 g, 0.034 mol) (UH-san manufactured by Ube Industries, Ltd.)
CARB300), 112.5 g of xylene and 37.5 g of cyclohexanone were charged and urethanized at 100 ° C. for 3 hours.

After returning the solution to room temperature, the carbodiimidation catalyst (3-methyl-1-phenyl-2-phospholene-1) was used.
-Oxide) (0.883 g, 4.59 mmol), p-isopropylphenyl isocyanate (6.4793 g, 40.
2 mmol) and stirred at 100 ° C. for 1 hour to carry out polymerization. Carbodiimidization was confirmed by IR spectrum. The number average molecular weight of this polycarbodiimide (M
n) was 5,400.

Example 1 The varnish produced in Production Example 1 was applied on a separator (thickness: 50 μm) composed of a polyethylene terephthalate film treated with a release agent. This was heated at 90 ° C. for 30 minutes and then at 150 ° C. for 30 minutes.
Heat the adhesive film (thickness of adhesive film layer 50
μm).

The adhesive strength between the obtained adhesive film and the silicon chip was measured as follows. That is, after peeling off the obtained adhesive film from the separator, 3
It was cut into cm □. This film is 2mm x 2mm x 7
Silicon chips (passive base) diced to 60 μm
Flip chip bonder sandwiched between a 3cm x 5cm glass epoxy substrate.
Using (Shibuya Kogyo DB100), a load (2.94 MPa) was applied at a temperature of 50 to 200 ° C., and heating was performed for 40 seconds for bonding, and the shear adhesive strength was measured. The results are summarized in Table 1.

Example 2 An adhesive film was obtained in the same manner as in Example 1 except that the varnish produced in Production Example 2 was used. The adhesive force between the adhesive film and the silicon chip was measured in the same manner as in Example 1. The results are summarized in Table 1.

Example 3 An adhesive film was obtained in the same manner as in Example 1 except that the varnish produced in Production Example 3 was used. The adhesive force between the adhesive film and the silicon chip was measured in the same manner as in Example 1. The results are summarized in Table 1.

Comparative Example 1 Tolylene diisocyanate (100 g, 0.57 mol) was placed in a 500 mL four-necked flask equipped with a stirrer, a dropping funnel, a reflux condenser, and a thermometer.
(Takenate 80 manufactured by Takeda Pharmaceutical Co., Ltd.), xylene 75
g, and 25 g of cyclohexanone.

Carbodiimidization catalyst (3-methyl-1-
Phenyl-2-phospholene-1-oxide) (0.883)
g, 4.59 mmol) and p-isopropylphenyl isocyanate (6.4793 g, 40.2 mmol), and the mixture was stirred at 100 ° C. for 1 hour to carry out polymerization. Carbodiimidization was confirmed by IR spectrum. The number average molecular weight (Mn) of this polycarbodiimide was 4,800. An adhesive film was obtained in the same manner as in Example 1 except that this varnish was used. The adhesive force between the adhesive film and the silicon chip was measured in the same manner as in Example 1. The results are summarized in Table 1.

Comparative Example 2 Tolylene diisocyanate (100 g, 0.57 mol) was placed in a 500 mL four-necked flask equipped with a stirrer, a dropping funnel, a reflux condenser, and a thermometer.
(Takenate 80 manufactured by Takeda Pharmaceutical Co., Ltd.), polyethylene glycol (100 g, 0.10 mol) (P manufactured by Sanyo Chemical Co., Ltd.)
EG-1000), 112.5 g of xylene and 37.5 g of cyclohexanone were charged and urethanized at 100 ° C. for 3 hours.

After returning the solution to room temperature, the carbodiimidation catalyst (3-methyl-1-phenyl-2-phospholene-1) was used.
-Oxide) (0.883 g, 4.59 mmol), p-isopropylphenyl isocyanate (6.4793 g, 40.
2 mmol) and stirred at 100 ° C. for 1 hour to carry out polymerization.

The carbodiimidization was confirmed by IR spectrum. The number average molecular weight of this polycarbodiimide (M
n) was 5,800.

Example 1 was repeated except that this varnish was used.
In the same manner as in the above, an adhesive film was obtained. The adhesive force between the adhesive film and the silicon chip was measured in the same manner as in Example 1. The results are summarized in Table 1.

Table 1 shows the above results. As is clear from Table 1, all of the examples show excellent adhesive strength at all temperatures from low to high temperatures as compared with the comparative examples.

[0058]

[Table 1] Physical properties of adhesive film of polycarbodiimide copolymer

[0059]

The adhesive film for die bonding of the present invention is
An adhesive layer having a uniform thickness and shape can be easily formed on the electrode member, can be fixed at a low temperature such as a normal temperature, and quality can be easily maintained. Further, the semiconductor chip can be fixed without requiring high temperature and high pressure, and the subsequent wire
It has heat resistance enough to withstand bonding connection and resin mold sealing.

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[Procedure amendment]

[Submission date] April 4, 2001 (2001.4.4)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction contents]

(Aromatic diisocyanate) In the formula ( I ), R2
Is an aromatic diisocyanate residue, and R ₂ is
For example, tolylene diisocyanate residue, diphenylmethane diisocyanate residue and the like can be mentioned. Also,
k is an integer of 0 to 30, and preferably 2 to 20. N is an integer of 0 to 30, preferably 2 to 30.
20.

Continued on the front page F-term (reference) 4J004 AA14 AB05 BA02 CA06 CA08 CB03 EA01 FA05 FA08 4J040 EF121 EF351 JA09 JB02 LA06 LA08 MA02 MB03 NA19 PA30 5F047 AA11 AA17 BA23 BA39 BB03 BB16

Claims (4)

[Claims] 1. The following formula:(Where k is an integer of 0 to 30, m is an integer of 2 to 100,
n is an integer of 0 to 30, R ₁Is alkylene having 2 to 10 carbon atoms
Group, R₂Is an aromatic diisocyanate residue, R₃Is aromatic
A group monoisocyanate residue is meant. )
Adhesive die for die bonding consisting of recarbodiimide copolymer
Film. 2. The adhesive film for die bonding according to claim 1, wherein, in the formula (I), R ₁ is a hexamethylene group, and R ₂ is a tolylene diisocyanate residue or a diphenylmethane diisocyanate residue. . 3. The adhesive film for die bonding according to claim 2, wherein in the formula (I), R ₃ is a p-isopropylphenyl isocyanate residue. 4. A semiconductor device comprising a semiconductor chip and electrodes fixed by the die-bonding adhesive film according to claim 1.