JP2003147046A - Resin paste for semiconductor and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a resin paste for a semiconductor, having excellent adhesive strength and low modulus in hot state, hardly causing separation of a resin paste layer for the semiconductor and corrosion of wiring in a solder crack resistance test and a moisture resistance test, and having excellent reliability. SOLUTION: This resin paste for the semiconductor consists essentially of (A) an epoxy resin, (B) a curing agent and (C) a filler. The epoxy resin contains >=5 pts.wt. compound represented by general formula (1) based on 100 pts.wt. epoxy resin. The contents of hydrolyzable chlorine in the compound of general formula (1) and the epoxy resin are each <=500 ppm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin paste for adhering a semiconductor element such as IC or LSI to a metal frame or the like.

[0002]

2. Description of the Related Art Conventionally, a resin paste for semiconductors has been generally used as a method for adhering a semiconductor element such as an IC to a lead frame. In response to the trend toward smaller and lighter electronic devices and higher functionality in recent years, semiconductor devices are becoming smaller, thinner, and narrower in pitch. There has been a strong demand for improvement in solder crack resistance and moisture resistance of a device after absorbing moisture. In order to improve the resistance to solder cracking, it is necessary that the semiconductor element and the lead frame be in close contact with each other and that stress during soldering be relaxed. However, in the conventional resin paste for semiconductors, it is difficult to achieve both compatibility between the adhesiveness of the lead frame or semiconductor element and the resin paste for semiconductors and lowering the elastic modulus at the time of heating, and the reliability of the semiconductor device is as high as expected. There was a problem that did not improve.

On the other hand, in order to improve the moisture resistance, it is essential to reduce impurities such as halogen ions and alkali metal ions in the resin paste for semiconductors and the sealing material. When the moisture absorption treatment of the semiconductor device is performed, the moisture concentration at each member interface increases, so that the amount of the ions dissolved in the moisture on the surface of the semiconductor element increases, causing corrosion of the wiring. To improve the solder crack resistance test, resin pastes for semiconductors using aliphatic epoxy have been reported, but there is a problem that the humidity resistance is poor because the chlorine concentration in the aliphatic epoxy is high. It was Therefore, there has been a demand for a highly reliable resin paste for semiconductors which does not cause peeling of the resin paste layer for semiconductors or corrosion of wiring of a semiconductor element in the solder cracking resistance test and the moisture resistance test.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to have excellent adhesive strength when heated and low elastic modulus when heated, and in the solder crack resistance test and moisture resistance test, peeling of the resin paste layer for semiconductors and semiconductor elements. Another object of the present invention is to provide a highly reliable resin paste for semiconductors in which the wiring corrosion does not occur.

[0005]

The present invention has (A) an epoxy resin, (B) a curing agent, and (C) a filler as essential components, and is represented by the general formula (1) in 100 parts by weight of the epoxy resin. The compound represented by the general formula (1)
And a resin paste for semiconductors in which the content of hydrolyzable chlorine in the compound represented by and the total epoxy resin is 500 ppm or less.

[Chemical 3] (R ₁ is an alkyl group having 6 to 12 carbon atoms) As a more preferable embodiment, a resin paste for semiconductors in which the compound represented by the general formula (1) is a compound represented by the formula (2) is used.

[Chemical 4] Further, the (A) epoxy resin is a resin paste for semiconductors in which the compound represented by the formula (2) and a bisphenol F type epoxy resin or a bisphenol A type epoxy resin which is liquid at 25 ° C. are used in combination. Further, it is a semiconductor device manufactured by using the above-mentioned semiconductor resin paste.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION General formula (1) used in the present invention
The compound represented by

[Chemical 5] (R ₁ is an alkyl group having 6 to 12 carbon atoms) and the content of hydrolyzable chlorine is 500 ppm or less. Since the compound represented by the general formula (1) is an aliphatic epoxy resin, chlorine is easily extracted, and the amount of hydrolyzable chlorine needs to be 500 ppm or less. If it exceeds 500 ppm, the amount of chlorine ions in the resin paste for semiconductors increases,
It is not preferable because it corrodes the wiring of the semiconductor element during the moisture resistance reliability test.

The present invention is characterized in that the compound represented by the general formula (1) is contained in an amount of 5 parts by weight or more in 100 parts by weight of the total epoxy resin. If it is less than 5 parts by weight, the adhesive strength is high, but the elasticity is high. The stress is too high to relax the stress, and peeling of the die attach layer occurs during evaluation of reflow resistance, which is not preferable. As a similar epoxy resin, there is also a compound in which R ₁ is an alkyl group having less than 6 carbon atoms, but it has a low boiling point and volatilizes during curing, bubbles are generated in the die attach layer, and a short distance between epoxy groups causes crosslinking. There are problems that density is high, elastic modulus is high, stress cannot be relaxed, and skin sensitization is strong, which is not preferable. In addition, a compound in which R ₁ is an alkyl group having more than 12 carbon atoms has difficulty in reducing hydrolyzable chlorine, has a long distance between cross-linking points, and has low adhesive strength, and has compatibility with an aromatic epoxy resin. It is not preferable because there is a problem that it is inferior to.

Examples of the epoxy resin represented by the general formula (1) include, but are not limited to, the compounds represented by the formulas (2), (3) and (4).

[Chemical 6]

[Chemical 7]

[Chemical 8]

Of these, the epoxy resin represented by the formula (2) is particularly preferable because it has a low viscosity and can reduce the amount of hydrolyzable chlorine.

The epoxy resin used together with the compound represented by the general formula (1) refers to all epoxy group-containing monomers, oligomers and polymers. For example, bisphenol A, bisphenol F, phenol novolac, polyglycidyl ether obtained by the reaction of cresol novolacs and epichlorohydrin, biphenyl type epoxy resin, stilbene type epoxy resin, hydroquinone type epoxy resin or other crystalline epoxy resin,
Heterocyclic epoxy resin such as diglycidyl hydantoin,
Alicyclic epoxy resins such as vinylcyclohexene dioxide, dicyclopentadiene dioxide, alicyclic diepoxy adipate, dicyclopentadiene-modified phenol type epoxy resin, triphenolmethane type epoxy resin, naphthol type epoxy resin, biphenylaralkyl type Examples thereof include epoxy resins and glycidyl amine, and these can be used alone or in combination of two or more.

As the epoxy resin used together with the compound represented by the general formula (1), those having a small molecular weight and being liquid at room temperature are preferable from the viewpoint of workability in compounding and viscosity after compounding. Among these, bisphenol F type epoxy resin and bisphenol A type epoxy resin which are liquid at 25 ° C. are particularly preferable because they are excellent in compatibility, low in viscosity and excellent in adhesive strength.

The total amount of hydrolyzable chlorine in the epoxy resin is
As with the compound represented by the general formula (1), it is preferably 500 ppm or less, and when it exceeds 500 ppm, chlorine ions in the resin paste for semiconductors increase and corrodes the wiring of the semiconductor element during the moisture resistance reliability test, which is not preferable.

When the epoxy resin is solid or semi-solid, or when it is liquid and has a high viscosity, it is preferable to use a reactive diluent having an epoxy group together. Examples of the reactive diluents include n-butyl glycidyl ether, versatic acid glycidyl ester, styrene oxide,
Examples thereof include phenyl glycidyl ether and cresyl glycidyl ether, and these can be used alone or 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,
Examples thereof include dicyandiamide, and these may be used alone or in combination of two or more.

The phenol resin preferably has two or more active hydrogen groups per molecule which react with an epoxy group and participate in crosslinking. Examples of such a phenol resin include bisphenol A, bisphenol F,
Bisphenol S, tetramethylbisphenol A, tetramethylbisphenol F, tetramethylbisphenol S, dihydroxydiphenyl ether, dihydroxybenzophenone, o-hydroxyphenol, m-hydroxyphenol, p-hydroxyphenol, biphenol, tetramethylbiphenol, ethylidene bisphenol, methylethylidene Phenol novolac resins and monohydric phenols obtained by reacting bis (methylphenol), cyclohexylidene bisphenol, monohydric phenols such as phenol, cresol and xylenol with formaldehyde in dilute aqueous solution under strong acidity Initial condensation products with polyfunctional aldehydes such as acrolein and glyoxal under acidic conditions, resorcin, catechol, hydroquino Initial condensate and the like of the acidic conditions of polyhydric phenols with formaldehyde etc., these can be used in combination of one or more.

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. These may be used alone or in combination. Can be used.

Examples of the imidazole compound include 2
-Methylimidazole, 2-ethylimidazole, 2-
Phenylimidazole, 2-phenyl-4-methylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2-phenyl-4,5-dihydroxy methyl imidazole, 2-C ₁₁ H ₂₃ - General such as imidazole 2,4-diamino-which has been added storage stability by adding imidazole, triazine and isocyanuric acid
6- {2-methylimidazole- (1)}-ethyl-S
-Triazine, its isocyanate adduct, etc. are mentioned, and these can be used alone or in combination of two or more.

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, the metal powder is mainly used for imparting electrical conductivity and thermal conductivity.

Examples of the organic fillers include silicone resins, fluororesins such as polytetrafluoroethylene, acrylic resins such as polymethylmethacrylate, benzoguanamine, and crosslinked products of melamine and formaldehyde. Among them, silver powder is particularly easily available for conductive purposes, there are many types of shapes and particle sizes, conductivity is good, and it is preferable in that the conductivity does not change even when heated,
Silica is preferable for the semiconductor resin paste for insulation because of its easy 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. Further, 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.

The particle size of the filler used varies depending on the required viscosity of the resin paste for semiconductors and is not particularly limited, but the average particle size is 0.3 to 20 μm, and the maximum particle size is 5.
It is preferably about 0 μm. If the average particle size is less than 0.3 μm, the viscosity becomes high, and if it exceeds 20 μm, bleeding may occur because the resin component flows out during coating or curing. When the maximum particle size exceeds 50 μm, when the resin paste for semiconductor is applied by the dispenser, the outlet of the needle is blocked and continuous use for a long time cannot be performed. Further, a relatively coarse filler and a fine filler may be mixed and used, and various types and shapes may be appropriately mixed.

Fillers other than the above may be used to impart the required properties. 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 material obtained by applying a metal coating to the surface of an organic filler, and the like can be mentioned. . The filler of the present invention may be one whose surface is previously treated with a silane coupling material such as alkoxysilane, acyloxysilane, silazane or organoaminosilane.

The resin paste for semiconductors of the present invention is (A)
Component (C) is an essential component, but in addition to these, if necessary, a curing accelerator, a stress reducing agent such as rubber or silicone, a silane coupling agent, a titanate coupling agent, a pigment, a dye, a defoaming agent. Additives such as agents, surfactants, and solvents can be appropriately added.

The resin paste for semiconductors of the present invention is (A)
To (C) component and other additives are premixed, kneaded by using a roll or the like, and then defoamed under vacuum to obtain. Using the semiconductor resin paste of the present invention,
A known method can be used to manufacture the semiconductor device.

[0024]

EXAMPLES The present invention will be specifically described with reference to Examples. The mixing ratio of each component is parts by weight. <Examples 1 to 5> Each component was mixed according to the formulation of Table 1,
The mixture was kneaded with a roll and defoamed using a vacuum chamber to obtain a resin paste for semiconductors. The obtained resin paste for semiconductors was evaluated by the following methods. The results are shown in Table 1.

<Raw material components used> Epoxy resin: Content of hydrolyzable chlorine represented by the formula (2): 300 pp
m epoxy resin (viscosity 10 mPa.s / 25 [deg.] C., epoxy equivalent 120) (hereinafter referred to as EP-1) -hydrolyzable chlorine content 1000p represented by formula (2)
pm epoxy resin (viscosity 10 mPa · s / 25 ° C., epoxy equivalent 125.) (hereinafter referred to as EP-2)

An epoxy resin represented by the formula (5) having a hydrolyzable chlorine content of 300 ppm (viscosity 10 mPa · s /
25 ° C, epoxy equivalent 105) (hereinafter referred to as EP-3)

[Chemical 9] ・ Bisphenol A type epoxy resin (viscosity 4000mP
a · s / 25 ° C., epoxy equivalent 190. Hydrolyzable chlorine content 200ppm) (hereinafter referred to as BPAEP)

Curing agent: Phenol novolac resin (hydroxyl group equivalent 104) Dicyandiamide 2-phenyl-4-methyl-5-hydroxymethylimidazole (hereinafter referred to as 2P4MHZ)

Inorganic filler: Silver powder: Particle size 0.1 to 30 μm, average particle size 3 μm, flake-Silica: Average particle size 3 μm, maximum particle size 20 μm, spherical

<Evaluation Method> Viscosity: Using an E-type viscometer (3 ° cone), 25 ° C,
The value at 2.5 rpm was measured. Impurity concentration: 5 g of the semiconductor resin paste was cured at 200 ° C. for 60 minutes using an oven. The hardened material was crushed, and 2 g of the powder passed through a 200-mesh sieve was put into a pressure-resistant container together with 40 g of distilled water and extracted at 120 ° C. for 20 hours. The chlorine ion concentration of the extracted water was measured by ion chromatography.

Adhesive strength: A 5 mm × 5 mm silicon chip was mounted on a copper frame using a resin paste for semiconductors and cured in an oven at 200 ° C. for 60 minutes. After curing, using a mount strength measuring device,
The die shear strength during heating at 260 ° C. was measured. Elasticity: A resin paste for semiconductors is applied on a fluororesin sheet in a width of 10 mm, a length of about 150 mm, and a thickness of 100 μm, and after curing in an oven at 200 ° C. for 60 minutes,
The tensile modulus was measured using a tensile tester at a test length of 100 mm, a tensile speed of 1 mm / 60 seconds, 25 ° C., or 260 ° C., and the elastic modulus was calculated from the initial gradient of the obtained stress-strain curve.

Solder resistance (peeling rate): A silicon chip (size 9.0 mm × 9.0 mm) is mounted on a lead frame (made of copper) using a resin paste for semiconductors, and an oven is used for 200 times in a nitrogen atmosphere. It was cured at 60 ° C. for 60 minutes. This lead frame is made of an epoxy resin encapsulant and is made of 80-pin QFP (package size 14 x 20
mm, thickness 2.0 mm) was transfer-molded at a mold temperature of 175 ° C., an injection pressure of 7.5 MPa and a curing time of 60 seconds, and post-cured at 175 ° C. for 8 hours. The obtained package was left in an environment of 85 ° C. and relative humidity of 85% for 168 hours and then immersed in a solder bath at 260 ° C. for 10 seconds. The total value of the peeling area inside the package was measured using a transmission type ultrasonic flaw detector, and the peeling area between the chip and the epoxy resin encapsulant and the lead frame and epoxy were measured using a reflection type ultrasonic flaw detector. The total value of the peeled area from the 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)], and the peeling rate of the resin paste for semiconductor is calculated as (peeling rate) = [ (Die-attach layer peeling area) / (chip area)] × 100, the average value of 5 packages was calculated and expressed as%. However, the cases where the peeled area by reflection in each package exceeds 25% were excluded from the calculation.

Moisture resistance: TEG for IC (size 9.0 m
m × 9.0 mm, aluminum wiring, line width 1 μm) is mounted on a lead frame (made of copper) using a resin paste for semiconductors, and an oven is used under nitrogen atmosphere at 200 ° C., 60 ° C.
Cured in minutes. After curing, gold wire wire bonding is performed, and 80-pin QFP is used with an epoxy resin encapsulant.
(Package size is 14 × 20mm, thickness 2.0m
m) was transfer-molded at a mold temperature of 175 ° C., an injection pressure of 7.5 MPa and a curing time of 60 seconds, and post-cured at 175 ° C. for 8 hours. A voltage of 10 V is applied to this package in an environment of 125 ° C. and a relative humidity of 85%, and after treatment for 500 hours, it is opened with fuming nitric acid and the TEG surface is observed.
It was confirmed whether aluminum wiring was corroded.

<Comparative Examples 1 to 8> Resin pastes for semiconductors were obtained in the same manner as in Example 1 according to the formulations shown in Table 2 and evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0034]

[Table 1]

[0035]

[Table 2]

[0036]

EFFECTS OF THE INVENTION According to the present invention, the adhesive strength at the time of heating is high and the elastic modulus at the time of heating is low, and the peeling of the resin paste layer for semiconductor and the wiring corrosion of the semiconductor element occur in the solder crack resistance test and the moisture resistance test. It is possible to obtain a highly reliable resin paste for semiconductors and a semiconductor device using the same.

Claims (4)

[Claims] 1. An epoxy resin 100 comprising (A) an epoxy resin, (B) a curing agent and (C) a filler as essential components.
The compound represented by the general formula (1) is contained in an amount of 5 parts by weight or more in parts by weight, and the hydrolyzable chlorine content of the compound represented by the general formula (1) and all epoxy resins is 500 ppm or less. Resin paste for semiconductors. [Chemical 1] (R ₁ is an alkyl group having 6 to 12 carbon atoms) 2. The resin paste for semiconductors according to claim 1, wherein the compound represented by the general formula (1) is a compound represented by the formula (2). [Chemical 2] 3. The resin for semiconductors according to claim 2, wherein the epoxy resin (A) is used in combination with the compound represented by the formula (2) and a bisphenol F type epoxy resin or a bisphenol A type epoxy resin which is liquid at 25 ° C. paste. 4. A semiconductor device manufactured by using the resin paste for semiconductor according to claim 1. Description: