JP2003268203A - Liquid epoxy resin composition for wafer mold and semiconductor apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid epoxy resin composition which is not affected by a warp even in a large-sized wafer such as 8 in., 12 in. or the like and which can be cut in individual semiconductor elements and attach a solder ball in a wafer state. <P>SOLUTION: The liquid epoxy resin composition for a wafer mold comprises the liquid epoxy resin composition using (A) a liquid epoxy resin, (B) a curing agent, and (C) an inorganic filler as essential components, wherein a tensile elastic modulus of the curing substance is 40-300 MPa and a surface altitude is 60-90 by a type D durometer. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid epoxy resin composition for wafer molding which can be suitably used for encapsulating electronic parts at the wafer level, and a semiconductor device using the same.

[0002]

2. Description of the Related Art The flip chip (FC) mounting method has been changed from the wire bonding method to the requirements for high integration and high density of IC chips and miniaturization and thinning of IC packages. It was
In the flip chip (FC) mounting method, metal bumps (solder balls, gold bumps) are generally used to electrically connect the silicon chip and the printed circuit board, but the thermal expansion coefficient is different, so thermal shock Thermal stress is generated during the test. In particular, local stress concentrates on the metal bumps around the chip. Therefore, the underfill material is used for sealing for the purpose of relaxing local stress. In this method, generally, a method of hardening after injecting the underfill material into the gap between the chip and the substrate by capillarity or pressure injection, but the process is complicated and it takes a long time, so that the cost is low. It becomes high. Furthermore, recently, with the increase in chip size, the increase in the number of bumps, and the reduction in the gap between the chip and the substrate, there is a problem that it takes a longer time to inject the underfill material.

Therefore, a large number of semiconductor elements having bumps (copper posts) for electrically connecting to a substrate are formed on a wafer and sealed with a liquid epoxy resin composition or a solid epoxy resin composition. A method of stopping has been proposed. When sealed by this method, a large number of semiconductor elements can be molded in a short time and can be easily obtained by dividing them into individual pieces. However, due to the recent demand for further cost reduction, the size of silicon wafers (8 inches, 12 inches, etc.) is increasing in order to obtain more semiconductor elements at one time,
The warpage of the substrate after sealing, which has not been a problem until now, has become a problem. This warpage becomes a great obstacle when solder balls are attached in a wafer state or when the wafer is cut into individual semiconductor elements. Also, if there is a large difference in the coefficient of thermal expansion between the resin layer and the silicon wafer, or between the copper posts, cracks may occur in the resin layer due to heating during mounting on the board or reliability test (temperature cycle) performed after mounting. However, there is a problem of reducing the reliability of the semiconductor device.

The present invention has been made in view of the above circumstances.
Liquid epoxy resin composition for wafer molding, which is not affected by warpage even when a large wafer is sealed, solves the problem of crack generation, and can provide a highly reliable semiconductor device, and a semiconductor device using the same The purpose is to provide.

[0005]

Means for Solving the Problems and Modes for Carrying Out the Invention As a result of earnest studies to achieve the above object, the present inventor contains a liquid epoxy resin, a curing agent, and an inorganic filler, and in this case, it is preferable. Contains a silicone-modified epoxy resin and / or a silicone-modified phenolic resin and uses an inorganic filler having a specific particle size distribution. By encapsulating with a liquid epoxy resin composition of ~ 90, even large wafers of 8 inches, 12 inches, etc. can be cut into individual semiconductor elements or wafers without being affected by warpage. Solder balls can be attached in this state, and the difference in thermal expansion coefficient between the resin layer and the silicon wafer and between the copper posts The present invention found that a highly reliable semiconductor device can be obtained in order to absorb the thermal stress caused by heating during mounting on a substrate and the temperature cycle after mounting and prevent the problem of cracking in the resin layer. Came to make.

Therefore, the present invention is a liquid epoxy resin composition containing (A) liquid epoxy resin (B) curing agent (C) inorganic filler as an essential component, and the cured product has a tensile modulus of 40 to 40. 300 MPa,
Also provided is a liquid epoxy resin composition for wafer molding, which has a surface hardness of 60 to 90 as measured by a type D durometer, and a semiconductor device which is sealed with the liquid epoxy resin composition.

The present invention will be described in more detail below.
The liquid epoxy resin composition of the present invention contains (A) liquid epoxy resin (B) curing agent (C) inorganic filler.

Liquid epoxy resin (A) used in the present invention
Any known liquid may be used as long as it is a liquid having two or more epoxy groups per molecule known in the related art. For example, bisphenol A type epoxy resin, bisphenol AD type epoxy resin, bisphenol F type epoxy resin, naphthalene type epoxy resin, biphenyl type epoxy resin, glycidyl amine type epoxy resin, alicyclic epoxy resin, dicyclopentadiene type epoxy resin, etc. Can be mentioned. These may be used alone or in combination of two or more. Of these, naphthalene type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD type epoxy resin and the like are preferable because they have relatively low viscosity and excellent heat resistance and moisture resistance.

The total chlorine content of these liquid epoxy resins is preferably 1500 ppm or less, more preferably 1000 ppm or less, and the extracted water chlorine at 100 ° C. at 50% epoxy resin concentration for 20 hours has a chlorine content of 10 p.
It is preferably pm or less. Total chlorine content is 150
If it exceeds 0 ppm, or if the amount of extracted water chlorine exceeds 10 ppm, the reliability of the semiconductor element, particularly the moisture resistance, may be adversely affected.

As the curing agent (B) for the liquid epoxy resin, any one can be used as long as it cures the liquid epoxy resin, but a phenol resin having two or more phenolic hydroxyl groups in one molecule is used. Particularly preferably used. For example, phenol novolac resin, cresol novolac resin, triphenol methane type resin,
Phenol aralkyl resins and the like are listed.

In the present invention, in order to reduce the stress, it is preferable to blend a silicone-modified epoxy resin and a silicone-modified phenol resin as the epoxy resin and the phenol resin. In this case, as such components, the alkenyl group of the alkenyl group-containing epoxy resin or phenol resin and the number of silicon atoms in one molecule represented by the following average composition formula (1) are 20 to 400, and the number of SiH groups is It is preferable to add a copolymer obtained by an addition reaction of the organopolysiloxane of 1 to 5 with the SiH group. H _a R _b SiO _{(4-ab) / 2} (1) (wherein R is a substituted or unsubstituted monovalent hydrocarbon group,
a is 0.01 to 0.1, b is 1.8 to 2.2, 1.81
It is a positive number of ≦ a + b ≦ 2.3. )

As the monovalent hydrocarbon group for R, one having 1 to 10 carbon atoms, particularly 1 to 8 carbon atoms is preferable, and a methyl group,
Alkyl groups such as ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, hexyl group, octyl group, decyl group, vinyl group, allyl group,
Alkenyl groups such as propenyl group, butenyl group, hexenyl group, aryl groups such as phenyl group, xylyl group, tolyl group, aralkyl groups such as benzyl group, phenylethyl group, phenylpropyl group, and hydrogen of these hydrocarbon groups. Examples thereof include halogen-substituted monovalent hydrocarbon groups such as a fluoromethyl group, a bromoethyl group, and a trifluoropropyl group in which some or all of the atoms are substituted with halogen atoms such as chlorine, fluorine, and bromine.

Of the above copolymers, those having the following structures (2) and (3) are preferable.

[0014]

[Chemical 1] (In the formula, R is the same as above, and R¹Is a hydrogen atom or
Lysidyl group, R²Is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.
R group, R³Is -CH₂CH₂CH₂-, -OCH ₂−
CH (OH) -CH₂-O-CH₂CH₂CH₂-Or-O
-CH₂CH₂CH₂− n is 0 to 100, preferably
Or an integer of 2 to 60, p is an integer of 1 to 10, and q is 1 to 1.
It is an integer of 0. )

[0015]

[Chemical 2] (In the formula, R is the same as above, R³Is a hydrogen atom or glycidyl
Lu group, R^FourIs a hydrogen atom, R ^FiveIs a divalent hydrocarbon group
Preferably 1 to 5 carbon atoms, more preferably 1 carbon atom
To 3 alkylene groups. m is an integer of 0 or more, preferably
It is 0 to 60, and more preferably 10 to 40. )

Here, the glycidyl group of R ¹ and R ³ is represented by the following formula.

[0017]

[Chemical 3]

The silicone-modified epoxy resin and the silicone-modified phenolic resin are blended in an amount of 10 to 50 parts by weight, preferably 30 to 40 parts by weight, and 40 to 40 parts by weight of the silicone-modified phenolic resin, based on 100 parts by weight of the resin. -60 parts by weight, preferably 50-60
Parts by weight.

The above silicone-modified phenol resin acts as a curing agent for the epoxy resin, and thus it can be used as a curing agent.

In the resin composition of the present invention, the compounding ratio of the silicone-modified epoxy resin, the epoxy resin containing the silicone-modified phenolic resin and the phenolic resin is 0.8 in terms of an equivalent ratio in consideration of known epoxy resin and phenolic resin. ≤
It is desirable that (epoxy group) / (phenolic hydroxyl group) ≦ 1.25, particularly 0.9 ≦ (epoxy group) /
It is desirable that (phenolic hydroxyl group) ≦ 1.1. If the equivalent ratio is not within this range, some unreacted,
The characteristics of the cured product and the performance of the semiconductor device using the cured product may be impaired.

In the present invention, as the curing agent,
For example, all acid anhydrides such as methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylhymic acid anhydride, and trialkyltetrahydrophthalic anhydride are preferably used. When such an acid anhydride is used as the curing agent, 0.7 to 1.3 mol, particularly 0.9 to 1.1 mol of the acid anhydride is added to 1 mol of the epoxy group in the epoxy resin. If it is less than 0.7 mol, the curability may be insufficient, and if it exceeds 1.3 mol, unreacted acid anhydride remains, lowering the glass transition temperature and reducing heat resistance. It may decrease.

In addition to the above, organic acid hydrazides such as dicyandiamide, adipic acid dihydrazide and isophthalic acid hydrazide can be used as the curing agent.

In the present invention, various conventionally known inorganic fillers (C) are added for the purpose of reducing the expansion coefficient. As the inorganic filler, for example, fused silica,
Crystalline silica, alumina, boron nitride, aluminum nitride, silicon nitride, magnesia, magnesium silicate and the like are used. In addition,
These inorganic fillers may be used alone or in combination. The content of the inorganic filler is 60 to 80 in the entire composition.
It is desirable that the content is 65% by weight, and more desirably 65 to
A range of 75% by weight is preferred. If it is less than 60% by weight, the expansion coefficient is large, which may cause a problem of warpage after curing. If it exceeds 80% by weight, the viscosity may be high and the surface condition may be poor.

The inorganic filler has a maximum particle size of 45 μm.
The above content is 1% by weight or less, and the average particle size is 1 to 1.
It is preferably 0 μm. Here, the maximum particle size is 45μ
When the content of m or more exceeds 1% by weight, not only the surface condition after sealing is deteriorated, but also when the epoxy resin composition is screen-printed, the openings are clogged with the inorganic filler and the coating amount is unsatisfactory. It may become uniform.

If the average particle size is less than 1 μm,
Since the viscosity of the epoxy resin composition is too high and the coating amount by one screen printing is small, multiple printing is required and the printing time becomes long, which is not practical.
When it exceeds 0 μm, when the epoxy resin composition is screen-printed, the openings are filled with the inorganic filler and the coating amount becomes uneven.

From the viewpoint of dispersibility, it is preferable to use those inorganic fillers which have been surface-treated with a coupling agent such as a silane coupling agent or a titanium coupling agent in advance.

Furthermore, the liquid epoxy resin composition of the present invention contains 2-methylimidazole and 2-methylimidazole as a curing accelerator.
Ethyl-4-methylimidazole, 1-cyanoethyl-
Imidazole derivatives such as 2-methylimidazole and 2-phenyl-4,5-dihydroxymethylimidazole,
Organic phosphine compounds such as triphenylphosphine (hereinafter referred to as TPP) and tri (p-methylphenyl) phosphine are used.

These imidazole derivatives can be used both as a curing accelerator for an acid anhydride type curing agent and as a curing agent for an epoxy resin. When used as a curing accelerator, the epoxy resin and the curing agent are used. The total amount of 100
It is preferable to add it in the range of 0.1 to 10 parts by weight, particularly 0.5 to 6 parts by weight with respect to parts by weight. Addition amount is 0.
If the amount is less than 1 part by weight, the curability may decrease, and
If it exceeds 0 parts by weight, the curability is excellent, but the storage stability tends to decrease. When the curing agent is a phenol resin, a curing effective amount of the organic phosphine compound is preferably used as the curing accelerator.

The liquid epoxy resin composition of the present invention may be blended with silicone powder, silicone rubber, silicone oil, liquid polybutadiene rubber, acrylic core shell resin or the like for the purpose of reducing stress.

If necessary, the liquid epoxy resin composition of the present invention further comprises an adhesion improver such as a silane coupling agent,
A pigment such as carbon black, a dye, an antioxidant, an ion trap agent, a surface treatment agent (γ-glycidoxypropyltrimethoxysilane, etc.), and other additives can be added.

The liquid epoxy resin composition of the present invention comprises 80
It can be cured under conditions of from ~ 200 ° C for 30 minutes to 5 hours. In this case, the cured product has a tensile elastic modulus of 40.
˜300 MPa, preferably 40 to 100 MPa, more preferably 50 to 60 MPa, and the surface hardness of the cured product must be 60 to 90, especially 65 to 85 by a type D durometer. When the tensile modulus after curing is less than 40 MPa or the hardness is less than 60,
After sealing, the smoothness of the surface deteriorates in the polishing process for exposing the electrodes. On the other hand, when the tensile elastic modulus exceeds 100 MPa or the hardness exceeds 90, the substrate is warped and the obtained semiconductor element is adversely affected when the wafer is cut into individual pieces.

In the liquid epoxy resin composition of the present invention, for example, a liquid epoxy resin, a curing agent, an inorganic filler and other components are stirred, dissolved, mixed or dispersed simultaneously or separately with heating treatment if necessary. . Equipment for mixing, stirring, dispersing and the like of these mixtures is not particularly limited, but a liquor machine equipped with a stirring and heating device, three rolls,
A ball mill, planetary mixer or the like can be used. You may combine these apparatuses suitably.

Regarding the step of sealing the wafer, there is no particular problem even at room temperature, but the wafer and the resin are heated in advance, and the resin is obtained by printing or compression molding in the heated state. The viscosity can be lowered, and the printability and leveling property are improved.

Further, in the printing and sealing step, it is general that printing is carried out under normal pressure and then air and the like taken into the sealing resin is defoamed in a vacuum container or the like, but printing under reduced pressure is carried out. But there is no particular problem.

The viscosity of the liquid epoxy resin composition of the present invention at 25 ° C. is preferably 150 to 400 Pa · s, and more preferably 200 to 300 Pa · s.

[0036]

EFFECTS OF THE INVENTION By using the liquid epoxy resin composition of the present invention, even large wafers such as 8 inches and 12 inches can be cut into individual semiconductor elements or wafers without being affected by warpage. Solder balls can be attached in this state. Also, it absorbs the difference in thermal expansion coefficient between the resin layer and the silicon wafer and between the copper posts, and absorbs the thermal stress due to heating during mounting on the board and the temperature cycle after mounting, preventing the problem of cracking in the resin layer. Therefore, a highly reliable semiconductor device can be obtained.

[0037]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples. In the following examples, all parts are parts by weight. Further, silica is represented by weight% when the total amount of the epoxy resin composition is 100% by weight.

[Examples 1 to 3 and Comparative Examples 1 to 4] As shown in Table 1, the silicone-modified epoxy resin of the above formula (2) (wherein R is a methyl group, R ¹ is a glycidyl group, and R ^{2 is} Is a hydrogen atom, R ³ is —OCH ₂ —CH (OH) —CH ₂ —O—
CH ₂ CH ₂ CH ₂ —, p = 5, q = 5, n = 10), RE-310S as a bisphenol A type epoxy resin
(Nippon Kayaku Co., Ltd.), H as naphthalene type epoxy resin
P4032D (manufactured by Dainippon Ink and Chemicals, Inc.) and a silicone-modified phenol resin of the above formula (2) as a curing agent (wherein R is a methyl group, R ¹ is a hydrogen atom, R ² is a hydrogen atom, R
³ _{-OCH 2 -CH (OH) -CH 2} -O-CH 2 CH 2
CH ₂ −, p = 5, q = 5, n = 10), and 1 part of TPP (triphenylphosphine) as a curing accelerator,
1 part of KBM-403 (manufactured by Shin-Etsu Chemical Co., Ltd.) was added, and spherical fused silica (Tatsumori Co., Ltd. average particle diameter 2 μm, maximum particle diameter 10 μm) was further compounded at the content shown in Table 1 as an inorganic filler. Then, the liquid epoxy resin composition was obtained by uniformly kneading.

The following tests (a) to (f) were conducted on these resin compositions, and the evaluation results are shown in Table 1.

The curing conditions are 100 ° C. × 1 hour + 150 ° C. × 2 hours. (A) Viscosity According to JIS Z 8803, Bro at a measurement temperature of 25 ° C.
okfield HBDV III Cone & Pla
The value after 2 minutes was measured with te. (B) Tensile elastic modulus of the cured product The tensile elastic modulus at 25 ° C. was measured based on JIS K 7113. (C) Amount of warp The liquid epoxy resin composition was applied to an 8-inch wafer at 100%.
Screen-printed to a thickness of μm, and after printing 1
It was cured under the conditions of 00 ° C. × 1 hour + 150 ° C. × 2 hours. After cooling, the resin-coated surface of the prepared test piece (8-inch wafer) was placed on the upper side, the height difference of the wafer was measured using a laser displacement meter, and the amount of warpage was measured. (D) Surface hardness The surface hardness of the cured product was measured with a Durometer type D. (E) Moisture resistance reliability One 20 semiconductor device in which 14 pin DIP (a silicon chip with aluminum wiring is mounted on a 42 alloy frame and wired with a gold wire) with the resin composition shown in Table 1 is sealed.
21 ° C./100% RH / 2 atm / 100 hours, 300
After being left for 1000 hours, the number of packages showing an abnormal value due to disconnection / total number of packages was measured. (F) Thermal cycle resistant BT substrate and UPILEX (manufactured by Ube Industries: 50 μm thick)
Was coated with the resin composition of Table 1 at 8 mm × 8 mm × 50 μm, a silicon chip of 7 mm × 7 mm × 0.3 mm was mounted thereon, and 20 test pieces obtained by curing the resin composition were soldered at 240 ° C. / 10 seconds and liquid nitrogen / 10 seconds 10
The test piece was reciprocated once, 30 times, and 100 times to measure the number of test pieces with cracks and peeling / total number of test pieces.

[0041]

[Table 1]

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Haruyoshi Kuwahara             Gunma Prefecture Usui District, Matsuida Town             Shin-Etsu Chemical Co., Ltd. Silicone electronic materials             Inside the technical laboratory (72) Inventor Toshio Shiobara             Gunma Prefecture Usui District, Matsuida Town             Shin-Etsu Chemical Co., Ltd. Silicone electronic materials             Inside the technical laboratory F-term (reference) 4J002 CD02W CD03W CD05W CD13W                       CP17X DE077 DE147 DF017                       DJ007 DJ017 DK007 EL136                       EQ026 ET006 FB097 FB167                       FD017 FD090 FD146 FD150                       FD200 GJ02 GQ01                 4M109 AA01 CA12 GA10

Claims (4)

[Claims] 1. A liquid epoxy resin composition comprising (A) liquid epoxy resin (B) curing agent (C) inorganic filler as an essential component, wherein the cured product has a tensile elastic modulus of 40 to 300 MPa,
A liquid epoxy resin composition for wafer molding, which has a surface hardness of 60 to 90 as measured by a type D durometer. 2. The liquid epoxy resin composition for a wafer mold according to claim 1, which contains a silicone-modified epoxy resin and / or a silicone-modified phenol resin. 3. A maximum particle size of 4 as the inorganic filler (C).
An inorganic filler having a content of 5 μm or more and 1% by weight or less and an average particle diameter of 1 to 10 μm is contained in the range of 60 to 80% by weight based on the entire liquid epoxy resin composition. Item 3. A liquid epoxy resin composition for wafer molding according to Item 1 or 2. 4. A semiconductor device which is encapsulated with the liquid epoxy resin composition for wafer molding according to claim 1. Description: