JP2007063565A - Resin paste for semiconductor and semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin paste for a semiconductor which is excellent in the adhesion strength at a high temperature and has a low modulus of elasticity under elevated temperatures, and is free from the detachment of the semiconductor resin paste layer or the erosion of a wiring in a semiconductor element in solder crack resistance and moisture resistance tests. <P>SOLUTION: The resin paste for a semiconductor contains essential components of (A) an epoxy resin, (B) a curing agent and (C) a filler, wherein the epoxy resin contains 5 weight parts or over of a compound shown by a general formula (1), with 1,000 ppm or less of a hydrolyzable chlorine content, wherein R1 may be the same or different and represents a hydrogen atom or a 1-6C alkyl group and n is a positive number of 0-3, in average. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a resin paste for bonding a semiconductor element such as an IC or LSI to a metal frame, an organic substrate or the like.

  Conventionally, a semiconductor resin paste is generally used as a method of bonding a semiconductor element such as an IC to a lead frame. In response to the recent trend toward smaller and lighter electronic devices and higher functionality, semiconductor devices are becoming increasingly smaller, thinner, and narrower in pitch. Improvement of solder crack resistance and moisture resistance after moisture absorption of the apparatus has been strongly demanded. In order to improve solder crack resistance, it is necessary that the semiconductor element and the lead frame are in close contact with each other and that stress during the soldering process be relaxed. However, with conventional semiconductor resin pastes, it is difficult to achieve a balance between the adhesion between the lead frame and the semiconductor element and the resin paste for semiconductors and the reduction of the elastic modulus during heating, as much as the reliability of semiconductor devices is expected. There was a problem of not improving.

On the other hand, in order to improve moisture resistance, it is essential to reduce impurities in semiconductor resin paste and sealing material, particularly halogen ions and alkali metal ions. When the moisture absorption treatment of the semiconductor device is performed, the moisture concentration at the interface of each member increases, so that the number of ions dissolved in the moisture increases on the surface of the semiconductor element, thereby causing corrosion of the wiring. In order to improve the solder crack resistance test, a semiconductor resin paste using a polyfunctional epoxy resin has been reported. However, although the adhesive strength is improved, the elastic modulus is also increased, so the solder resistance is not improved. Examples using aliphatic polyfunctional epoxies and hydrogenated epoxies have also been reported, and it was possible to achieve both adhesive strength and elastic modulus, but the chlorine concentration in the resin is high and the moisture resistance reliability is poor. There was a problem.
For this reason, there has been a demand for a semiconductor resin paste having excellent reliability that does not cause peeling of the semiconductor resin paste layer or wiring corrosion of the semiconductor element in the solder cracking test and moisture resistance test.
Japanese Patent Application Laid-Open No. 07-026235

  The object of the present invention is excellent in adhesive strength during heating and low elastic modulus during heating, and in the reliability that does not cause peeling of the resin paste layer for semiconductors and wiring corrosion of semiconductor elements in the solder crack resistance test and moisture resistance test. The object is to provide an excellent resin paste for semiconductors.

The present invention comprises (A) an epoxy resin, (B) a curing agent, and (C) a filler as essential components, and contains 5 parts by weight or more of the compound represented by the general formula (1) in the epoxy resin. The resin paste for semiconductors in which the hydrolyzable chlorine content of the compound represented by (1) is 1000 ppm or less.
(R1 is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and may be the same or different. N is an average value of 0 to 3 positive numbers.)

As a more preferable form, the semiconductor paste is a compound represented by the general formula (1), which is a compound represented by the formula (2) or the formula (3).
(N is a positive number from 0 to 3 as an average value.)
(N is a positive number from 0 to 3 as an average value.)
The (A) epoxy resin is a resin paste for semiconductors in which a compound represented by the general formula (1) and a bisphenol F type epoxy resin or a bisphenol A type epoxy resin that are liquid at 25 ° C. are used in combination.
Moreover, it is a semiconductor device manufactured using the resin paste for semiconductors described above.

  According to the present invention, it has excellent adhesive strength when heated and low elastic modulus when heated, and has excellent reliability that does not cause peeling of the resin paste layer for semiconductor and wiring corrosion of the semiconductor element in the solder crack resistance test and moisture resistance test. A semiconductor resin paste and a semiconductor device using the same are obtained.

The epoxy resin represented by the general formula (1) used in the present invention is
(R1 is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and may be the same or different. N is an average value of 0 to 3 positive numbers.)
It is an epoxy resin having a hydrolyzable chlorine content of 1000 ppm or less. If it exceeds 1000 ppm, chlorine ions in the resin paste for semiconductors increase, which is not preferable for corroding the wiring of the semiconductor element during the moisture resistance reliability test, and the moisture resistance reliability is improved as the hydrolyzable chlorine content is decreased. .
When the average value of n in the general formula (1) exceeds 3, the viscosity is increased or the distance between epoxy groups is increased, so that the crosslink density of the cured product is lowered and the adhesive strength is lowered.

Since the epoxy resin represented by the general formula (1) has no aromatic ring in the molecule, it has a low viscosity and a low elastic modulus. Usually, when the elastic modulus decreases, the strength and adhesive strength of the cured product tend to decrease, but the epoxy resin represented by the general formula (1) has the same distance between epoxy groups as a normal bisphenol-type epoxy resin, It discovered that the intensity | strength and adhesive strength of hardened | cured material did not fall.
Examples of the epoxy resin represented by the general formula (1) include, but are not limited to, compounds represented by the formula (2), the formula (3), and the formula (4).

(N is a positive number from 0 to 3 as an average value.)
(N is a positive number from 0 to 3 as an average value.)
(N is a positive number from 0 to 3 as an average value.)

  Among these, the epoxy resins represented by the formulas (2) and (3) are easy to obtain a resin having a small amount of hydrolyzable chlorine, have a low viscosity, and are excellent in compatibility with other epoxy resins. This is particularly preferable.

Moreover, you may use together another epoxy resin in the range which does not impair the characteristic according to a use if needed. In this case, other epoxy resins refer to monomers, oligomers, and polymers in general having an epoxy group. For example, crystalline epoxy resins such as polyglycidyl ether, biphenyl type epoxy resin, stilbene type epoxy resin, hydroquinone type epoxy resin obtained by reaction of bisphenol A, bisphenol F, phenol novolak, cresol novolaks and epichlorohydrin, butanediol di Aliphatic epoxy resins such as glycidyl ether, neopentyl glycol diglycidyl ether, heterocyclic epoxy resins such as diglycidyl hydantoin, alicyclic such as vinylcyclohexene dioxide, dicyclopentadiene dioxide, alicyclic diepoxy adipate Epoxy resin, dicyclopentadiene modified phenolic epoxy resin, triphenolmethane epoxy resin, naphthol epoxy resin, biphenyl alcohol Examples thereof include aralkyl type epoxy resins and glycidylamines, and these can be used alone or in combination.
There are various types of epoxy resins depending on the molecular weight, but those having a small molecular weight and liquid at normal temperature are preferable from the viewpoint of workability when blended and viscosity after blending.
Of these, bisphenol F-type epoxy resin or bisphenol A-type epoxy resin which is liquid at 25 ° C. is particularly preferable in terms of excellent compatibility, low viscosity, and excellent adhesive strength.

  The ratio of the epoxy resin represented by the general formula (1) in the epoxy resin is 5 parts by weight or more with respect to 100 parts by weight of the total epoxy resin. If the ratio of the epoxy resin represented by the general formula (1) in the epoxy resin is less than 5 parts by weight, the elastic modulus of the cured product does not decrease, which is not preferable.

  When the epoxy resin is solid or semi-solid, or when the epoxy resin is liquid but has a high viscosity, it is preferable to use a reactive diluent having an epoxy group in combination. Examples of the reactive diluent include n-butyl glycidyl ether, versatic acid glycidyl ester, styrene oxide, ethylhexyl glycidyl ether, phenyl glycidyl ether, cresyl glycidyl ether, butylphenyl glycidyl ether, and the like. It is possible to use one kind or plural kinds in combination.

  Examples of the curing agent used in the present invention include imidazole compounds, phenol resins, dicarboxylic acid dihydrazide compounds, aliphatic amines, aromatic amines, dicyandiamide, and the like, and these may be used alone or in combination. Is possible.

  It is desirable that the phenol resin used for the curing agent has two or more active hydrogen groups per molecule that react with an epoxy group to be crosslinked. Examples of such phenol resins include bisphenol A, bisphenol F, bisphenol S, tetramethyl bisphenol A, tetramethyl bisphenol F, tetramethyl bisphenol S, dihydroxydiphenyl ether, dihydroxybenzophenone, o-hydroxyphenol, m-hydroxyphenol, p-Hydroxyphenol, biphenol, tetramethylbiphenol, ethylidene bisphenol, methyl ethylidene bis (methyl phenol), cyclohexylidene bisphenol, monohydric phenols such as phenol, cresol, xylenol and formaldehyde in a dilute aqueous solution under strong acidity Phenol novolac resin, monohydric phenols and acrolein, glyoxer Examples include acidic initial condensates with polyfunctional aldehydes such as, and acidic initial condensates of polyphenols such as resorcin, catechol, and hydroquinone with formaldehyde. It can be used in combination.

  Examples of the dicarboxylic acid dihydrazide compound include carboxylic acid dihydrazides such as adipic acid dihydrazide, dodecanoic acid dihydrazide, isophthalic acid dihydrazide, and p-oxybenzoic acid dihydrazide, and these may be used alone or in combination. Is possible.

Examples of the imidazole compound include 2-methylimidazole, 2-ethylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, and 2-phenyl-4. , 5-dihydroxy methyl imidazole, _2-C 11 _{H 23} - adds a generic imidazole or triazine and isocyanuric acid such as imidazole, diamino 2,4 imparted with storage stability 6- {
Examples include 2-methylimidazole- (1)}-ethyl-S-triazine, and its isocyanate adduct, and these can be used alone or in combination.

Examples of the filler used in the present invention include inorganic fillers and organic fillers.
Examples of the inorganic filler include metal powder such as gold powder, silver powder, copper powder, and aluminum powder, fused silica, crystalline silica, silicon nitride, alumina, aluminum nitride, talc, and the like. Among these, metal powder is mainly used for imparting electrical conductivity and thermal conductivity.
Examples of the organic filler include a silicone resin, a fluororesin such as polytetrafluoroethylene, an acrylic resin such as polymethyl methacrylate, a cross-linked product of benzoguanamine, melamine, and formaldehyde.
Among them, silver powder is particularly easily available for conductive applications, and there are many types of shapes and particle diameters, good electrical conductivity, and preferable because it does not change conductivity even when heated. Silica is preferable for the resin paste in terms of availability and variety.
These fillers preferably have a content of ionic impurities such as halogen ions and alkali metal ions of 10 ppm or less.
In addition, as the shape of the filler, for example, a flake shape, a scale shape, a resin shape, a spherical shape, or the like is used.

  Although the particle size of the filler to be used varies depending on the required viscosity of the resin paste for semiconductor, it is usually preferable that the average particle size is 0.3 to 20 μm and the maximum particle size is about 50 μm. If the average particle size is less than the lower limit, the viscosity increases, and if it exceeds the upper limit, the resin component flows out during coating or curing, and bleeding may occur. When the maximum particle size exceeds the upper limit, when the semiconductor resin paste is applied with a dispenser, the needle outlet is blocked and continuous use for a long time cannot be performed. Moreover, a comparatively coarse filler and a fine filler can also be mixed and used, and various kinds of shapes and shapes may be appropriately mixed.

  In order to impart the required characteristics, fillers other than those described above may be used. For example, a nanoscale filler having a particle size of about 1 to 100 nm, a composite material of silica and acrylic, a composite filler of an organic compound and an inorganic compound, such as a metal coating on the surface of the organic filler, etc. . The filler of the present invention may be prepared by treating the surface with a silane coupling material such as alkoxysilane, acyloxysilane, silazane, or organoaminosilane in advance.

The resin paste for semiconductors of the present invention comprises the components (A) to (C) as essential components, but in addition to these, a curing accelerator, a low stress agent such as rubber or silicone, a silane coupling agent, Additives such as titanate coupling agents, pigments, dyes, antifoaming agents, surfactants, and solvents can be appropriately blended.
The semiconductor resin paste of the present invention is obtained by a production method such as premixing the components (A) to (C) and other additives, kneading using a roll or the like, and then degassing under vacuum. .
A known method can be used to manufacture a semiconductor device using the semiconductor resin paste of the present invention.

The present invention will be specifically described with reference to examples. The blending ratio of each component is parts by weight.
<Examples 1-7>
Each component was mixed according to the composition of Table 1, kneaded with a roll, and defoamed using a vacuum chamber to obtain a resin paste for semiconductor. The obtained resin paste for semiconductor was evaluated by the following method. The results are shown in Table 1.

<Comparative Examples 1-9>
Resin pastes for semiconductors were obtained in the same manner as in the examples and evaluated in the same manner as in the examples. The results are shown in Table 2.

<Used raw material components>
·Epoxy resin:
Epoxy resin having a hydrolyzable chlorine content of 700 ppm represented by the formula (2) (viscosity 400 mPa · s / 25 ° C., epoxy equivalent 190, n = 0.3) (hereinafter referred to as EP-1)
Epoxy resin having a hydrolyzable chlorine content of 500 ppm represented by formula (3) (viscosity 1500 mPa · s / 25 ° C., epoxy equivalent 210, n = 0.3) (hereinafter referred to as EP-2)
Epoxy resin having a hydrolyzable chlorine content of 1500 ppm represented by the formula (2) (viscosity 400 mPa · s / 25 ° C., epoxy equivalent 190, n = 0.3) (hereinafter referred to as EP-3)
Epoxy resin having a hydrolyzable chlorine content of 700 ppm represented by the formula (2) (semi-solid / 25 ° C., epoxy equivalent 675, n = 4.0) (hereinafter referred to as EP-4)
Bisphenol A type epoxy resin (viscosity 4000 mPa · s / 25 ° C., epoxy equivalent 190) (hereinafter referred to as BPAEP)
・ Curing agent:
Phenol novolac resin (hydroxyl equivalent 104)
Dicyandiamide 2-phenyl-4-methyl-5-hydroxymethylimidazole (hereinafter referred to as 2P4MHZ)

・ Inorganic filler:
Silver powder: particle size 0.1-30 μm, average particle size 3 μm, flake shape.
Silica: average particle size 3 μm, maximum particle size 20 μm, spherical

<Evaluation method>
Viscosity: The value at 25 ° C. and 2.5 rpm was measured using an E-type viscometer (3 ° cone). Impurity concentration: 5 g of resin paste for semiconductor was cured in an oven at 200 ° C. for 60 minutes. The cured product was pulverized, and 2 g of the powder passed through sieving with a 200 mesh sieve was placed in a pressure vessel together with 40 g of distilled water, and extracted at 120 ° C. for 20 hours. Chlorine ion concentration of the extracted water was measured by ion chromatography.
Adhesive strength: A silicon chip of 5 mm × 5 mm was mounted on a copper frame using a resin paste for semiconductor, and cured in an oven at 200 ° C. for 60 minutes. After curing, the die shear strength during heating at 25 ° C. and 260 ° C. was measured using a mount strength measuring device.
-Modulus of elasticity: A resin paste for semiconductor is applied to a fluorine resin sheet to a width of 10 mm, a length of about 150 mm, and a thickness of 100 μm, cured in an oven at 200 ° C. for 60 minutes, and then tested using a tensile tester. The elastic modulus was calculated from the initial gradient of the obtained stress-strain curve, measured at 100 mm, a pulling speed of 1 mm / 60 seconds, 25 ° C., or 260 ° C.
Solder resistance (peeling rate): A silicon chip (size: 9.0 mm × 9.0 mm) is mounted on a lead frame (copper) using a resin paste for semiconductor, and an oven is used at 200 ° C., 60 in a nitrogen atmosphere. Cured in minutes. This lead frame was transferred and molded with an 80-pin QFP (package size: 14 x 20 mm, thickness: 2.0 mm) using an epoxy resin sealing material at a mold temperature of 175 ° C, an injection pressure of 7.5 MPa, and a curing time of 60 seconds. Post-curing was performed at 175 ° C. for 8 hours. The obtained package was left for 168 hours in an environment of 85 ° C. and 85% relative humidity, and then immersed in a solder bath at 260 ° C. for 10 seconds. Measure the total peel area inside the package using a transmissive ultrasonic flaw detector, and use the reflective ultrasonic flaw detector to peel off the chip and epoxy resin encapsulant and lead frame. The total value of the peeled area with the epoxy resin sealing material was measured. (Peeling area of die attach layer) = [(Total value of peeling area in transmission) − (Total value of peeling area in reflection)] is obtained, and the peeling rate of the resin paste for semiconductor is (peeling rate) = [ (Die attach layer peeling area) / (chip area)] × 100, the average value of the five packages was determined and displayed in%.
Moisture resistance: TEG for IC (size: 9.0 mm × 9.0 mm, aluminum wiring, wire width: 1 μm) is mounted on a lead frame (copper) using a semiconductor resin paste, and 200 ° C. in a nitrogen atmosphere using an oven. Cured at 60 ° C. for 60 minutes. After curing, wire wire bonding is performed, and an 80-pin QFP (package size: 14 × 20 mm, thickness: 2.0 mm) is used with an epoxy resin sealing material, a mold temperature of 175 ° C., an injection pressure of 7.5 MPa, and a curing time. Transfer molding was performed for 60 seconds, followed by post-curing at 175 ° C. for 8 hours. The package was treated with a voltage of 10 V under an environment of 125 ° C. and a relative humidity of 85% for 500 hours, then opened with fuming nitric acid, and the surface of the TEG was observed to confirm the presence or absence of aluminum wiring corrosion.

Claims (4)

(A) An epoxy resin, (B) a curing agent, and (C) a filler are essential components, the epoxy resin contains 5 parts by weight or more of the compound represented by the general formula (1), and the general formula (1) The resin paste for semiconductors characterized by the hydrolyzable chlorine content of the compound shown being 1000 ppm or less.

(R1 is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and may be the same or different. N is an average value of 0 to 3 positive numbers.) The resin paste for a semiconductor according to claim 1, wherein the compound represented by the general formula (1) is a compound represented by the formula (2) or the formula (3).

(N is a positive number from 0 to 3 as an average value.)

(N is a positive number from 0 to 3 as an average value.) (A) The resin paste for semiconductors of Claim 1 or 2 in which the epoxy resin uses together the compound shown by General formula (1), and the bisphenol F type epoxy resin or bisphenol A type epoxy resin which is liquid at 25 degreeC. The semiconductor device manufactured using the resin paste for semiconductors in any one of Claims 1-3.