CN110684319A

CN110684319A - Method for manufacturing semiconductor packaging composition

Info

Publication number: CN110684319A
Application number: CN201810729076.6A
Authority: CN
Inventors: 刘程秀
Original assignee: Individual
Current assignee: Individual
Priority date: 2018-07-05
Filing date: 2018-07-05
Publication date: 2020-01-14

Abstract

The present invention relates to a method for producing a semiconductor encapsulating composition, characterized in that a semiconductor element is encapsulated with an epoxy resin composition comprising an epoxy resin (A), a curing agent (B) and an inorganic filler, wherein the inorganic filler contains silica (C) as an essential component, the curing agent (B) is a curing agent containing at least 2 phenolic hydroxyl groups and/or naphthol hydroxyl groups per molecule, and the silica (C) contains 2 to 99% by weight of synthetic silica and 99 to 2% by weight of natural fused silica.

Description

Method for manufacturing semiconductor packaging composition

Technical Field

The present invention relates to a method for producing a semiconductor encapsulating composition, and more particularly to a method for producing an epoxy resin composition for a semiconductor encapsulating composition, an epoxy resin composition having excellent moldability, and a semiconductor device encapsulated with the epoxy resin composition and having excellent moisture resistance reliability, high temperature reliability and solder heat resistance.

Background

The resin-encapsulated semiconductor device is now available in the market, and compared with a semiconductor device manufactured by another encapsulation method, the resin-encapsulated semiconductor device has low encapsulation cost, good mass productivity, and an increased range of application. As the encapsulating resin for the application in the market, a composition of phenol resin, silicone resin, epoxy resin, and the like can be used, and a resin encapsulation using an epoxy resin composition is becoming a trend from the viewpoint of balance among economy, productivity, and physical properties. However, with the actual demands for semiconductor devices such as larger area, thinner size, and more pins, there are problems in that the resin composition is used for encapsulation in production. The problems of moldability are mainly expressed (a) when the resin composition is used for packaging, the resin filling is insufficient during transfer molding along with the increase of the area of the package shape, and pores are easily generated on the package; second, the problem of resin peeling is that when a package having a complicated shape such as a multi-pin package is formed, a part of the resin of the package peels off. Third, as the thickness of the package is reduced, the allowable offset width for molding of the chip or the gold wire is extremely small, and thus it is very difficult to adapt the semiconductor package resin composition to the use of the conventional resin composition. In order to solve these problems, attempts have been made to improve the fluidity of a resin composition, reduce the amount of an inorganic filler, change the gel time or change the resin itself to lower the viscosity, but these methods have been difficult to satisfy all the required properties, such as improvement of the fluidity, and in the case where transfer molding is repeated, the resin composition flows into a corner of a mold to cause a problem of corner-block, and attempts have been made to improve the fluidity of the resin composition at the time of molding by specifying the shape of the filler of the inorganic filler, and to improve the fluidity, but the composition has been improved in europe, and an epoxy resin composition comprising a combination of an epoxy resin having a biphenyl skeleton, a curing agent, and silica having a specific size has been used, and has been insufficient for improving solder heat resistance, moisture resistance reliability, moldability, and particularly resin peeling of a semiconductor device, but the problems are not solved very well on the basis of other problems.

Disclosure of Invention

In order to solve the above problems, the present invention provides an epoxy resin composition having a low melt viscosity, which can be repeatedly molded without corner plugging of a metal mold, and can provide a molded article free from resin peeling, voids, and table surface offset; to provide a semiconductor device which ensures moisture-proof reliability, high-temperature reliability and solder heat resistance when a semiconductor element is packaged. The epoxy resin composition of the present invention is an epoxy resin composition comprising an epoxy resin (A), a curing agent (B) and an inorganic filler. An epoxy resin composition in which the inorganic filler contains silica (C) containing 2 to 99 wt% of synthetic silica and 99 to 2 wt% of natural fused silica; the curing agent (B) contains at least 2 phenolic hydroxyl groups and/or naphtholic hydroxyl groups per molecule. The preparation method comprises the following steps: the epoxy resin composition is composed of a synthetic silica containing SiO2 as a main component, which is obtained by chemical reaction of natural SiO2, and a step of mixing an epoxy resin (A), a curing agent (B) containing at least 2 phenolic hydroxyl groups and/or naphthol hydroxyl groups per molecule, and a synthetic silica (2 to 99% by weight of the total weight of the silica), and a natural fused silica (99 to 2% by weight of the total weight of the silica).

The present invention can improve the moldability of an epoxy resin composition to a large extent, and can mold a semiconductor device without causing defects such as unfilled resin, resin falling, gold wire slipping, mesa shift, and corner clogging during molding. The semiconductor device encapsulated with the epoxy resin composition is excellent in moisture resistance reliability, high temperature reliability and solder heat resistance, and can exhibit desirable characteristics as an electronic component. The resin composition has good moldability and is also suitable for precision molded parts.

Detailed Description

The production and effect of the present invention will be described in detail below.

The epoxy resin (a) used in the present invention is not particularly limited, and may be any resin having an epoxy group in the molecule. The epoxy resin (a) used may be a bisphenol a type epoxy resin, a bisphenol C type epoxy resin, a hydrogenated bisphenol type epoxy resin, a bisphenol F type epoxy resin, a phenol novolac type epoxy resin, a cresol novolac type epoxy resin, an epoxy resin containing an alicyclic structure such as a dicyclopentadiene ring, a biphenyl type epoxy resin, an epoxy-modified silicone or the like, and these epoxy resin compositions may be used alone or in a mixture of two or more. Among these epoxy resins (A), the resin containing 50 wt% or more of biphenyl type epoxy resin (wherein R is a hydrogen atom, or the same or different monovalent organic carbon groups usually having 2 to 4 carbon atoms) is preferably used in the present invention, and a partially polymerized structure due to the reaction of epoxy groups may be used. Preferable examples of the epoxy resin include diglycidyl ether of 3,3 ', 5, 5' -tetramethyl-4, 4 '-dihydroxybiphenyl, diglycidyl ether of dimethyl dipropyl bisphenol, diglycidyl ether of 3, 3', 5,5 '-tetra-tert-butyl-4, 4' -dihydroxybiphenyl, and diglycidyl ether of dimethyl bisphenol.

The curing agent (B) of the present invention is a substance which can be cured by reacting with the epoxy resin (a), and any curing agent having a phenolic hydroxyl group and/or a naphtholic hydroxyl group structure such as two or more phenol groups, cresol groups, xylenol groups and the like per molecule can be used without particular limitation. Specific examples of the curing agent (B) may be phenol novolac resin, cresol novolac resin, naphthol novolac resin, copolymers of those novolac resins shown above, bisphenol a, bisphenol F, phenol aralkyl resin, naphthol aralkyl resin, trihydroxymethane, trihydroxyethane and bisphenol resin, and copolymers thereof. These curing agents (B) may be used in combination of two or more, and the amount thereof to be added is preferably 34 to 300 parts by weight per 100 parts by weight of the epoxy resin (A). From the viewpoint of functional groups, the ratio of the epoxy equivalent of the epoxy resin (a) to the hydroxyl equivalent of the curing agent (B) (epoxy equivalent/hydroxyl equivalent) is preferably 0.7 to 1.3.

The silica (C) of the present invention contains 1 to 99 wt% of synthetic silica as an essential component. When the amount of synthetic silica is small, resin falling off is likely to occur during molding, while when the amount of synthetic silica is large, defects such as external pores are likely to occur, and problems such as poor flowability tend to occur during molding. The synthetic silica referred to herein is a silica which is artificially synthesized by a chemical reaction, the raw material substance of which is not SiO2 as a main component, and any of these synthetic silicas can be used without particular limitation. Examples of the method for producing the synthetic silica include a method of using Si as a raw material by an oxidation reaction, a method of using a sol gel using monoalkyltrialkoxysilane, dialkyldialkoxysilane, tetraalkoxysilane (tetraalkylorthosilicate), or the like as a raw material, a method of hydrolyzing monoalkyltrichlorosilane, tetrachlorosilane, trichlorosilane, or the like, and then dehydrating by heating or decomposing and oxidizing by a direct oxyhydrogen flame, and a method of using polysiloxane as a raw material to oxidize the same. The size of the synthetic silica is not particularly limited as an essential component in the silica (C). However, the average particle diameter of the synthetic silica is preferably in the range of 0.15 to 30 μm, particularly preferably 0.15 to 3.0 μm, from the viewpoints of reliability at high temperature, reliability in moisture resistance, solder heat resistance, prevention of defects in semiconductor devices, and the like. Considering the molding of semiconductor devices such as device chips which are particularly susceptible to damage, the average particle size of the synthetic silica is preferably in the range of 0.16 to 30 μm, and most preferably 0.17 to 0.9 μm, due to contamination caused by impurities. The shape of the synthetic silica is not particularly limited, but is preferably spherical in view of fluidity at the time of molding, and therefore, the portion having an acute angle shape in the synthetic silica is preferably 50 wt% or less. The mixed silica as the silica (C) in the present invention contains 99 to 2 wt% of natural fused silica in addition to 2 to 99 wt% of synthetic silica. Natural fused silica is obtained by melting a starting material such as silica containing SiO2 as a main component in advance. The size of the natural fused silica is not particularly limited, but is preferably in the range of 1.5 to 51 μm, particularly 3.5 to 51 μm in view of high-temperature reliability, moisture resistance reliability, and solder heat resistance. The shape of the natural fused silica is not particularly limited, but in consideration of fluidity at the time of molding, the shape of the silica should not be an acute angle, that is, a spherical shape is preferable. The content of particles having an acute shape, which are broken shapes contained in the natural fused silica, is preferably less than 30 wt% of the total amount of the silica (C). In the mixed silica as the silica (C), the mixing ratio of the synthetic silica and the natural fused silica is 2 to 99 wt%, preferably 6 to 94 wt%, particularly preferably 5 wt% and 10 wt% in this order as the lower limit amount of the mixing amount, and preferably 50 wt% and 30 wt% in this order as the upper limit amount. The natural fused silica is preferably 99 to 1 wt%, more preferably 94 to 5 wt%, particularly preferably 50 wt% or 70 wt% in the order of the lower limit, and 94 wt% or 90 wt% in the order of the upper limit. The amount of silica (C) blended in the epoxy resin composition of the present invention is not particularly limited, but is preferably 85 wt% or more, particularly preferably 88 wt% or more, of the total amount in order to improve the high-temperature reliability, moisture-proof reliability and solder heat resistance of the resulting molded article. In the epoxy resin composition of the present invention, it is effective to use an organosilane coupling agent in combination. The organosilane coupling agent is a compound in which an organic group and a hydrolyzable group such as an alkoxy group, an acetoxy group, a halogen atom, or an amino group are directly bonded to a silicon atom. In particular, a substance containing an epoxy group or a substance containing an amino group as an organic group is preferably used because it provides a significant effect on the present invention. The amount of the organosilane coupling agent is preferably 0.02 to 5 wt% based on the total amount of the resin composition. Among the compounds having amino groups, compounds having secondary amino groups are particularly preferred, and compounds in which all amino groups are secondary amino groups are more preferred. Examples of the organosilane coupling agent include the following compounds. Examples of the compound having an unsubstituted organic group include vinyltriethoxysilane, vinyltrimethoxysilane, vinyltriacetoxysilane and vinyltrichlorosilane. As the compound having an epoxy group, there are gamma-glycidoxypropyltriethoxysilane and gamma-glycidoxypropyltrimethoxysilane. As the amino group-containing compound, there are gamma- (2-aminoethyl) aminopropyltriethoxysilane, gamma- (2-aminoethyl) aminopropyltrimethoxysilane, gamma-phenylaminopropyltrimethoxysilane, gamma-phenylaminopropyltriethoxysilane, N-BETA- (N-vinylbenzylaminoethyl) -gamma-aminopropyltriethoxysilane and N-BETA- (N-vinylbenzylaminoethyl) -gamma-aminopropyltrimethoxysilane. As other kinds of compounds, there are gamma-glycidoxypropylvinylethoxysilane, gamma-mercaptopropyltrimethoxysilane, gamma-glycidoxypropyltrimethoxysilane, gamma-mercaptopropyltriethoxysilane, gamma-methacryloxypropylmethyldimethoxysilane, gamma-ureidopropyltriethoxysilane, gamma-ureidopropyltrimethoxysilane. Various waxes such as montanic acid wax, polyethylene wax and magnesium stearate, and various release agents such as long-chain fatty acids, fatty acid metal salts, metal salts of long-chain fatty acids, long-chain fatty acid esters or amides, and various modified silicone compounds may be blended and used in the epoxy resin composition of the present invention. In the use of semiconductor devices, flame retardancy is sometimes required, and therefore, an organic halide such as a brominated bisphenol a glycidyl ether, a brominated cresol novolak resin, or a brominated epoxy resin, or a flame retardant such as a phosphorus compound may be used in combination. Flame retardant aids such as antimony pentoxide, antimony tetraoxide, and antimony trioxide may also be used. In the resin composition of the present invention, from the viewpoint of high-temperature reliability, moisture-proof reliability, and solder heat resistance, the content of halogen atoms and antimony atoms introduced into the flame retardant and flame retardant auxiliary is preferably as small as possible, and the content of each atom is preferably 0.25 wt% or less based on the epoxy resin composition. The inorganic filler may contain, in addition to silica (C), an inorganic compound such as borosilicate glass, talc, alumina, zirconia, magnesia, hydrotalcite calcium carbonate, clay, magnesium carbonate, calcium silicate, antimony oxide, titanium oxide, or the like, as necessary, within a range not to impair the effects of the present invention. The amount of the inorganic filler to be blended in the epoxy resin composition of the present invention is not particularly limited, but is preferably 84 wt% or more, particularly preferably 88 wt% or more, based on the total amount, in order to improve the high-temperature reliability, moisture resistance reliability and solder heat resistance of the resulting molded article. In addition, in the epoxy resin composition of the present invention, various phosphine compounds such as tri-p-tolylphosphine, tri-o-tolylphosphine, triphenylphosphine, tri- (2, 6-dimethoxyphenyl) phosphine, tri-m-tolylphosphine, various phosphonium salts such as tetraethylphosphonium bromide, tetraphenylphosphonium tetraphenylborate, tetraethylphosphonium tetraphenylborate, tetrabutylphosphonium bromide and tetrabutylphosphonium tetraphenylborate, and various phosphonium salts such as 1, 8-diaza-bicyclo- (5,4,0) undec-7-ene (DBU), 1-methylimidazole, 2-methylimidazole, imidazole, 1, 2-dimethylimidazole, 2-phenylimidazole, 1-phenylimidazole, DBU phenol novolak resin salt, DBU p-toluenesulfonate and 1, and curing accelerators such as various amine compounds including 5-diaza-bicyclo (4,3,0) non-5-ene (DBN), 1-benzylimidazole, phenol of DBU, and octyl salt of DBU. In addition, various colorants such as iron oxide and carbon black, various thermoplastic resins such as silicone rubber, various pigments, various elastomers such as olefin copolymers, modified nitrile rubber, polyethylene, and modified polybutadiene rubber, and crosslinking agents such as organic peroxides can be used. The epoxy resin composition of the present invention is prepared by mixing the epoxy resin (a), the curing agent (B), the inorganic filler and other additives with a banbury mixer or the like, melt-kneading the mixture with various mixers such as a single-screw or twin-screw extruder, a kneader and a hot roll mill, cooling the mixture, and pulverizing the cooled mixture. The composition of the present invention thus obtained can form a precision part, and in particular, a precision part produced using a composition containing 84 wt% or more of silica (C) in the resin composition has excellent dimensional stability. When a ball that circumscribes the precision component is assumed as the shape of the precision component, the minimum diameter of the ball is preferably as small as 31mm or less. The semiconductor device of the present invention is characterized in that a semiconductor element is encapsulated by using the above epoxy resin composition, and has excellent moisture-resistant reliability, high-temperature reliability and soldering resistance in addition to good commercial appearance.

The synthetic silica A-1 thus prepared was pulverized for a predetermined time and passed through a sieve having a mesh size of 72 μm to prepare a pulverized synthetic silica A-2. The average particle diameters of the prepared synthetic silicas A-1 and A-2 were measured by laser light scattering to be 51 μm and 21 μm, respectively. Synthetic example A spherical synthetic silica A-3 was prepared by dissolving and mixing tetraethyl orthosilicate in an ethanol solvent in such a ratio that 1 mol of gamma-aminopropyltrimethoxysilane and 50 mol of water were added to each mol of tetraethyl orthosilicate, separating the resulting white turbid liquid, treating the solution with 1/1 of a water/methanol mixture, and drying the solution at 500 ℃ for 23 hours. The average particle diameter of the synthetic silica C obtained was 0.33. mu.m as measured by a laser light scattering method. Synthesis example B trichlorosilane was used as a raw material, and synthesized silica A-4 having an average particle size of 11 μm and synthesized silica A-5 having an average particle size of 42 μm were obtained by hydrolysis and heating in a known manner. Similarly, using metallic silicon as a raw material, synthetic silica A-6 having an average particle diameter of 0.6 μm and synthetic silica A-7 having an average particle diameter of 1.1 μm were prepared through the processes of explosive vapor phase oxidation, condensation and solidification. Silica obtained by melting silica is pulverized or made into a spherical shape to obtain 5 kinds of natural fused silica B-1 to B-5 having different shapes and average particle diameters.

To 100 parts by weight of the total amount of the mixture, 0.6 parts by weight of gamma-glycidoxypropyltriethoxysilane, 0.2 parts by weight of montanic acid wax and 0.15 parts by weight of carbon black were added, 1.05 parts by weight of triphenylphosphine was added based on 100 parts by weight of the total amount of the epoxy resin and the curing agent, and the mixture was dry-blended in a mixer and then melt-kneaded in an extruder to obtain an epoxy resin composition. And then the mixture is crushed again and then tabletted. The lowest melt viscosity at 175 ℃ was determined using a high-viscosity viscometer using a pellet of the epoxy resin composition. "Hot hardness" is the Barcol hardness after molding, which was obtained by molding a disk having a diameter of 4 inches and a thickness of 3mm from an epoxy resin composition at a molding temperature of 175 ℃ for a molding time of 90 seconds. The "moldability" was measured by molding a QFP (QUAD FLAT PACKAGE) of 160 pins from an epoxy resin composition at a molding temperature of 175 ℃ for a molding time of 90 seconds, and observing the peeling of the resin, the occurrence of voids, and the clogging of the corners of a mold during molding. Mesa-offset molded chip size 12X 12mm, package size 28X 28mm X3.4 mm (thickness) of 160-pin QFP, and secondary curing at 180 ℃ for 5 hours. The obtained test piece was cut perpendicularly to the Island (Island) surface, and the cross section was observed with a microscope to observe whether or not the mesa was shifted. High temperature reliability is. Wiring was performed on a silicon chip by aluminum vapor deposition, the aluminum pad was removed, the semiconductor element passivated with the nitride film was connected to the internal lead wire through a gold wire, dip (dual Inline package) of 16 pins was molded with various epoxy resin compositions, and post-curing was performed at 180 ℃ for 5 hours. The device was then immersed in a solder bath at 260 c for 120 seconds and then placed under an atmosphere at 190 c. After 50 hours, the wiring resistance was measured, and the time when the resistance value reached 10 times the initial resistance value was obtained, which time was called high-temperature reliability. The longer the time, the better. The moisture resistance reliability is a device obtained by the same procedure as the high temperature reliability evaluation, and after immersion in a solder bath at 260 ℃ for 120 seconds, it is left under conditions of 121 ℃ and 100% RH. After 50 hours, the time taken to reach the break was measured and the time was called the reliability of the moisture resistance. The longer the time, the better. Solder Heat resistance A100-pin QFP, in which a polyimide-coated silicon chip was die-bonded, was encapsulated with various epoxy resin compositions and post-cured at 170 ℃ for 5 hours to prepare a plurality of samples. Next, specimens were prepared which were kept at 86 ℃ and 84% RH for various periods of time (every 13 hours) and then subjected to IR reflow at temperatures up to 265 ℃. The presence or absence of external cracking after reflow was observed, and the minimum value of the standing time of the sample at 86 ℃ and 84% RH before IR reflow was observed as the solder heat resistance. The longer the time, the better.

The epoxy resin composition of the present invention hardly causes defects such as unfilled resin, resin falling, offset of a mesa and corner clogging, and has excellent moldability, and a semiconductor device packaged with the epoxy resin composition has excellent moisture resistance reliability, high temperature reliability, mesa offset prevention property and solder heat resistance in a well-balanced manner. These effects are particularly remarkable when an epoxy resin is used, that is, when an epoxy resin having a biphenyl type epoxy group is used, or when the silica content is 84% or more, particularly 88% or more. In addition, as the silane coupling agent, when a silane coupling agent in which all the amino groups are secondary amino groups is used, these effects are more remarkable. On the contrary, when synthetic silica is used alone or natural fused silica is used alone, not only moldability is poor but also a semiconductor device excellent in reliability cannot be obtained. As described above, the epoxy resin composition of the present invention is excellent in moldability because defects such as unfilled resin, resin peeling, offset of a mesa surface, and corner clogging do not occur during molding, and thus it is suitably used as a precision molded part. Furthermore, the semiconductor device of the present invention encapsulated with the epoxy resin composition of the present invention has excellent moisture resistance reliability, high temperature reliability, and solder heat resistance, and therefore exhibits desirable performance as an electronic component. As described above, the epoxy resin composition of the present invention can be used not only for various precision parts but also for semiconductor device packaging applications to provide a semiconductor device having excellent reliability, because of its excellent moldability.

Claims

1. A method for producing a semiconductor encapsulating composition, characterized in that the epoxy resin composition comprises an epoxy resin (A), a curing agent (B) and an inorganic filler, wherein the inorganic filler contains silica (C) as an essential component, the curing agent (B) is a curing agent containing at least 2 phenolic hydroxyl groups and/or naphtholic hydroxyl groups per molecule, and the silica (C) contains 2 to 99% by weight of synthetic silica and 99 to 2% by weight of natural fused silica.

2. The semiconductor encapsulating composition according to claim 1, wherein the inorganic filler accounts for 85% by weight or more of the resin composition, and wherein the content of the silica (C) accounts for 85% by weight or more of the resin composition.

3. A semiconductor device packaging composition according to any one of claims 1 to 2, characterized in that the mixed silica contains 5 to 50% by weight of spherical synthetic silica and 95 to 50% by weight of natural fused silica.

4. The content of silica having a crushed shape contained in the natural fused silica is 30% by weight or less; synthetic silica contained in the silica (C) has an average particle diameter of 0.1 to 30 μm, and natural fused silica contained in the silica (C) has an average particle diameter of 1 to 50 μm; the synthetic silica contained in the silica (C) has an average particle diameter of 0.1 to 3 μm, and the natural fused silica contained in the silica (C) has an average particle diameter of 3 to 50 μm.

5. A semiconductor device encapsulating composition according to any one of claims 1 to 3, characterized in that the epoxy resin composition contains a silane coupling agent in which an organic group having an epoxy group is directly bonded to a silicon atom, the epoxy resin composition contains a coupling agent in which an organic group having an amino group is directly bonded to a silicon atom, wherein the silane coupling agent is a silane coupling agent whose amino group is a secondary amino group; the halogen atom content in the composition is 0.2 wt% or less, and the antimony atom content is 0.2 wt% or less.

6. A method of manufacturing a semiconductor device according to claims 1 to 3, characterized in that the semiconductor element is packaged by transfer molding.

7. The method for producing a semiconductor device according to claim 5, wherein the epoxy resin (A) comprises a biphenyl type epoxy group as an essential component, and the amount of silica is 85% by weight or more of the resin composition.

8. The method for manufacturing a semiconductor device according to claim 6, wherein the amount of the synthetic silica is 6 to 50% by weight and the amount of the natural fused silica is 95 to 51% by weight based on the total amount of the silica.