KR20150056048A - Epoxy resin composition for sealing semiconductor and semiconductor device - Google Patents

Abstract

The present invention relates to an epoxy resin composition for an encapsulating semiconductor and a semiconductor device with an excellent reliability which have a high adhesion with a plating of CuLF or Ag even in the case of a long-period storing under a high temperature of 175 to 250°C, and have no disconnection and corrosion at Cu wire, and a contacting part of Cu wire with Al pad. The epoxy resin composition for an encapsulating semiconductor of the present invention comprises (A) an epoxy resin; (B) a curing agent; (C) an inorganic filter; (D) bismuth hydroxide or bismuth subcarbonate; and (E) a phosphazen compound represented by the following average composition formula (1) [In the formula, X is a single bond or a group selected from CH_2, C(CH_3)_2, SO_2, S, O and O(CO)O, and d, e, and n is a number satisfying 0<=d<=0. 25n, 0<=e<2n, 2d+e=2n, and 3<=n<=1,000] as an essential component, and does not comprise bromide, red phosphorus, phosphoric ester and an antimonic compound.

Description

[0001] EPOXY RESIN COMPOSITION FOR SEALING SEMICONDUCTOR AND SEMICONDUCTOR DEVICE [0002]

The present invention relates to an epoxy resin composition for semiconductor encapsulation which is excellent in reliability at a long-term high temperature and is free from peeling off from a Cu lead frame (LF) or an Ag plated portion and does not cause corrosion or migration of a Cu wire, To a semiconductor device sealed with a cargo.

In recent years, global environmental measures such as global warming countermeasures and energy conversion from fossil fuels have been going on, and the number of cars producing hybrid cars and electric cars is increasing. In addition, home electric appliances in emerging countries such as China and India are increasingly equipped with inverter motors as energy saving measures.

In the hybrid vehicle, the electric vehicle and the inverter, a power semiconductor which plays the role of converting AC into DC, DC into AC, or transforming the voltage becomes important. However, silicon (Si), which has been used for a long time as a semiconductor, has come close to the performance limit, and it has been difficult to expect a remarkable improvement in performance. Therefore, attention is focused on a next generation type power semiconductor using materials such as silicon carbide (SiC), gallium nitride (GaN), and diamond. For example, in order to reduce the loss in power conversion, it is required to lower the resistance of the power MOSFET, but it is difficult to significantly lower the resistance in the mainstream Si-MOSFET. Accordingly, development of a low-loss power MOSFET using SiC having a wide bandgap (wide gap) semiconductor is underway. SiC or GaN has excellent characteristics such that the band gap is about 3 times that of Si and the breakdown field strength is 10 times or more. It also features high temperature operation (650 ° C operation is reported in SiC), high thermal conductivity (Cu grade in SiC), and large saturated electron drift speed. As a result, when SiC or GaN is used, the on-resistance of the power semiconductor can be lowered and the power loss of the power conversion circuit can be greatly reduced. However, in view of the fact that the temperature on the element is expected to generate heat at 175 DEG C or higher, heat resistance characteristics are required for the surrounding materials including the sealing agent.

On the other hand, power semiconductors are generally protected by transfer molding using an epoxy resin or potting and sealing with silicone gel. In recent years, transfer molding by epoxy resin has become mainstream in view of small size and light weight (especially in automotive applications). The epoxy resin is a thermosetting resin which is excellent in moldability, adhesion to a base material and mechanical strength and balanced, but reliability characteristics in a temperature range exceeding 175 캜 are questionable. In fact, when a semiconductor device sealed with an existing sealing material was left at a high temperature of 200 ° C for 500 hours, cracks occurred in the sealing material, peeling occurred at the interface between the sealing material and the Ag plating die pad, There are cases in which reliability is affected, such as cracks in the alloy layer.

As the prior art related to the present invention, the following documents can be cited.

IEEE Transactions on Components and packing Technology, Vol. 26, No. 2, 367-374 SEMICON Singapore 2005, 35-43 Journal of Materials Science (2008) 43, 6038-6048

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a copper clad laminate which is excellent in adhesion of CuLF or Ag plating even when stored at a high temperature of 175 to 250 ° C for a long period of time, And an object of the present invention is to provide an epoxy resin composition for semiconductor encapsulation and a semiconductor device which can be used as the excellent semiconductor device.

(B) a curing agent, (C) an inorganic filler, (D) bismuth hydroxide or bicarbonate, and (E) an average composition formula 1), and the epoxy resin composition for semiconductor encapsulation substantially containing no bromide, phosphoric acid ester, and antimony compound is excellent in reliability when stored for a long period at a high temperature, Further, it has been found that a semiconductor device which is sealed with a cured product of the composition is excellent in flame retardancy and reliability at high temperature, and has achieved the present invention.

Accordingly, the present invention provides an epoxy resin composition for semiconductor encapsulation and a semiconductor device described below.

(1) A resin composition comprising (A) an epoxy resin,

(B) a curing agent,

(C) an inorganic filler,

(D) bismuth hydroxide or bismuth carbonate,

(E) a phosphazene compound represented by the following average composition formula (1)

Wherein X is a single bond or a group selected from CH ₂ , C (CH ₃ ) ₂ , SO ₂ , S, O and O (CO) O, and d, e and n satisfy 0≤d≤0.25n , 0? E <2n, 2d + e = 2n, 3? N?

, And is substantially free of bromide, phosphoric acid, phosphoric acid ester and antimony compound.

[2] The epoxy resin composition according to [1], wherein the amount of bismuth hydroxide or bismuth carbonate (D) is 3 to 10 parts by mass based on 100 parts by mass of the total of the components (A) and (B).

[3] The epoxy resin composition according to [1] or [2], wherein the epoxy equivalent (A) of the epoxy resin is less than 210.

[4] The epoxy resin composition according to any one of [1] to [3], wherein (A) the epoxy resin is an epoxy resin represented by the following formula (2)

(Wherein a is an integer of 1 to 10)

[5] A semiconductor device encapsulated with a cured product of the epoxy resin composition according to any one of [1] to [4].

INDUSTRIAL APPLICABILITY The epoxy resin composition for semiconductor encapsulation of the present invention can obtain a cured product excellent in moldability and excellent in flame retardancy and reliability at high temperatures. In addition, since the antimony compound such as bromide such as brominated epoxy resin and antimony trioxide is not contained in the epoxy resin composition, there is no adverse effect on the human body and the environment. Further, the epoxy resin composition for semiconductor encapsulation of the present invention can obtain a cured product having excellent hot water extraction characteristics and excellent moisture resistance reliability, as compared with an epoxy resin composition to which a phosphorus flame retardant such as phosphoric ester is added. Further, the semiconductor device encapsulated with the cured product of the epoxy resin composition for semiconductor encapsulation of the present invention is excellent in flame retardancy, reliability at high temperature, and is particularly useful in industry.

Hereinafter, the present invention will be described in more detail.

The epoxy resin composition for semiconductor encapsulation of the present invention comprises

(A) an epoxy resin,

(B) a curing agent,

(C) an inorganic filler,

(D) bismuth hydroxide or bismuth carbonate,

(E) a phosphazene compound represented by the following average composition formula (1)

Wherein X is a single bond or a group selected from CH ₂ , C (CH ₃ ) ₂ , SO ₂ , S, O and O (CO) O, and d, e and n satisfy 0≤d≤0.25n , 0? E <2n, 2d + e = 2n, 3? N?

And is substantially free of bromide, phosphoric acid, phosphate ester and antimony compound.

Here, the term "substantially not included" means that the composition is not intentionally added to the composition, and it is industrially acceptable to incorporate it into the contaminant.

The epoxy resin (A) constituting the epoxy resin composition of the present invention is not particularly limited. Examples of common epoxy resins include novolak type epoxy resins, cresol novolak type epoxy resins, triphenolalkane type epoxy resins, aralkyl type epoxy resins, biphenyl skeleton-containing aralkyl type epoxy resins, biphenyl type epoxy resins, dicyclopentadiene Type epoxy resin, a cyclic epoxy resin, a naphthalene ring-containing epoxy resin, a bisphenol A type epoxy compound, a bisphenol F type epoxy compound, a steel benzyl type epoxy resin, and the like. can do. In the present invention, a brominated epoxy resin is not blended.

Among these, a cured product having a high glass transition temperature is generally preferable for a semiconductor device requiring high-temperature insulation and mechanical strength. As such a cured product, there is a high crosslinking density and a high epoxy group concentration, This low epoxy resin is suitably used. The epoxy equivalent is preferably less than 210, more preferably less than 170. The triphenalkalene type represented by the following general formula (2) has an epoxy equivalent weight of 168. [

(Wherein a is an integer of 1 to 10)

The epoxy resin preferably has a hydrolyzable chlorine content of 1,000 ppm or less, particularly 500 ppm or less, and a content of sodium and potassium of 10 ppm or less, respectively. If the amount of hydrolyzable chlorine exceeds 1,000 ppm, or if sodium or potassium exceeds 10 ppm, moisture resistance may deteriorate if the semiconductor device is left under a high temperature and high humidity for a long time.

The (B) curing agent used in the present invention is not particularly limited. As typical curing agents, phenol resins are preferable, and specific examples thereof include phenol novolak resins, naphthalene ring-containing phenol resins, aralkyl type phenol resins, triphenolalkane type phenol resins, biphenyl skeleton-containing aralkyl type phenol resins, Bisphenol type phenol resins such as phenol resin, alicyclic phenol resin, heterocyclic phenol resin, naphthalene ring-containing phenol resin, bisphenol A type resin and bisphenol F type resin, and one kind or two kinds Or more can be used in combination.

It is preferable that the content of sodium and potassium in the curing agent is 10 ppm or less, respectively, like the epoxy resin. If the sodium or potassium exceeds 10 ppm, the moisture resistance may deteriorate if the semiconductor device is left under a high temperature and high humidity for a long time.

Here, the blending amount of the epoxy resin and the curing agent is not particularly limited, but it is preferable that the molar ratio of the phenolic hydroxyl group contained in the curing agent to one mole of the epoxy group contained in the epoxy resin is in the range of 0.5 to 1.5, particularly 0.7 to 1.2.

Further, in the present invention, it is preferable to use a curing accelerator to accelerate the curing reaction between the epoxy resin and the curing agent. The curing accelerator is not particularly limited as long as it accelerates the curing reaction. Examples of the curing accelerator include triphenylphosphine, tributylphosphine, tri (p-methylphenyl) phosphine, tri (nonylphenyl) , Phosphorus compounds such as triphenylborane, tetraphenylphosphine-tetraphenylborate, triphenylphosphine and adducts of benzoquinone, triethylamine, benzyldimethylamine,? -Methylbenzyldimethylamine, 1,8-diazabicyclo Tertiary amine compounds such as cyclo (5.4.0) undecene-7, imidazole compounds such as 2-methylimidazole, 2-phenylimidazole and 2-phenyl-4-methylimidazole .

Although the amount of the curing accelerator is effective, the curing accelerator for accelerating the curing reaction of the epoxy resin and the curing agent (phenol resin) such as the phosphorus compound, the tertiary amine compound, the imidazole compound, It is preferably 0.1 to 5 parts by mass, particularly 0.5 to 2 parts by mass, based on 100 parts by mass of the total amount.

As the inorganic filler (C) to be blended into the epoxy resin composition of the present invention, those blended in the epoxy resin composition can be used. For example, silica such as fused silica and crystalline silica, alumina, silicon nitride, aluminum nitride, boron nitride, titanium oxide, glass fiber and the like can be given.

The average particle diameter and shape of the inorganic filler and the fill amount of the inorganic filler are not particularly limited. However, in order to improve the flame retardancy, it is preferable to fill the epoxy resin composition as much as possible within a range that does not impair moldability. In this case, spherical fused silica having an average particle size of 5 to 30 μm and an average particle size of the inorganic filler is particularly preferable, and the filling amount of the inorganic filler of the component (C) Is preferably from 400 to 1,200 parts by mass, particularly preferably from 500 to 1,000 parts by mass, per part by mass.

The inorganic filler is preferably one that has been surface-treated with a coupling agent such as a silane coupling agent or a titanate coupling agent in order to strengthen the bonding strength between the resin and the inorganic filler. Examples of such coupling agents include epoxy silanes such as? -Glycidoxypropyltrimethoxysilane,? -Glycidoxypropylmethyldiethoxysilane and? - (3,4-epoxycyclohexyl) ethyltrimethoxysilane, N-β (Aminoethyl) -? - aminopropyltrimethoxysilane,? -Aminopropyltriethoxysilane and N-phenyl-? -Aminopropyltrimethoxysilane, aminosilane such as? -Mercaptopropyltrimethoxysilane Of mercaptosilane and the like are preferably used. The mixing amount of the coupling agent used in the surface treatment and the surface treatment method are not particularly limited.

In the epoxy resin composition for semiconductor encapsulation of the present invention, (D) bismuth hydroxide or bismuth carbonate is used.

The effects of the bismuth compound so far include an effect as an inorganic ion exchanger for exchanging anions derived from phosphate ester (Japanese Patent Application Laid-Open No. 2003-147169), a laser marking improving effect (Japanese Patent Application Laid-Open No. Hei 6-84601), a combination with a brominated epoxy resin, and a halogenated gas trap effect under a high temperature atmosphere (Japanese Patent Application Laid-Open No. 11-240937).

In the present invention, among bismuth compounds, bismuth hydroxide and bismuth subcarbonate are supplemented with organic acids other than halogen and do not emit corrosive anions, so that adhesion to CuLF or Ag plating is maintained even under long- Wire, Cu wire / Al pads, breakage of joints, corrosion and the like. Among epoxy resins, a resin having a low epoxy equivalent, for example, a triphenolalkane type epoxy resin represented by the above-mentioned general formula (2) is effective in combination with bismuth hydroxide and bicarbonate bichromate since the concentration of organic acid generated by thermal decomposition is high .

(D) The amount of bismuth hydroxide or bismuth carbonate to be added is preferably 3 to 10 parts by mass, more preferably 3 to 8 parts by mass, per 100 parts by mass of the total amount of the components (A) and (B). If the amount is less than 3 parts by mass, the characteristics may not be sufficiently exhibited. If it exceeds 10 parts by mass, there is a possibility of causing fluidity lowering or hardening failure.

Further, nitrate ions are preferably 10 mass% or less as impurities in bismuth hydroxide and bicarbonate carbonate.

The epoxy resin composition for semiconductor encapsulation of the present invention comprises (E) a phosphazene compound represented by the following average composition formula (1).

Wherein X is a single bond or a group selected from CH ₂ , C (CH ₃ ) ₂ , SO ₂ , S, O and O (CO) O, and d, e and n satisfy 0≤d≤0.25n , 0? E <2n, 2d + e = 2n, 3? N?

The epoxy resin composition for semiconductor encapsulation according to the present invention, to which the phosphazene compound represented by the above formula (1) is added, is superior to the epoxy resin composition to which a phosphorus flame retardant such as phosphoric acid ester is added, A cured product having particularly excellent moisture resistance can be obtained.

Here, in the formula (1), n is 3 to 1,000, more preferably 3 to 10. Especially preferably n = 3 in the synthesis.

d and e are 0? d? 0.25n, 0? e <2n and 2d + e = 2n. At 0.25 n < d, since the intermolecular crosslinking of the phosphazene compound is large, the softening point is high and it is difficult to use in the epoxy resin, and the expected flame retardant effect is not obtained. e is 0 < = e &lt; 2n, but in order to achieve flame retardancy at a high level, it is preferable that 1.5n &amp;le;

When X is a single bond,

.

The amount of the phosphazene compound to be added is preferably 1 to 10 parts by mass, particularly preferably 3 to 7 parts by mass based on 100 parts by mass of the total amount of the components (A) and (B). If the addition amount is less than 1 part by mass, a sufficient flame retardant effect may not be obtained. If the addition amount is more than 10 parts by mass, the fluidity and the glass transition temperature may be lowered.

In the epoxy resin composition for semiconductor encapsulation of the present invention, various additives may be further added as necessary. For example, waxes such as a thermoplastic resin, a thermoplastic elastomer, an organic synthetic rubber, a low stress agent such as silicone, a carnauba wax, a higher fatty acid, a synthetic wax, a colorant such as carbon black, May be added and mixed in a range that does not impair the object of the present invention.

The epoxy resin composition for semiconductor encapsulation of the present invention can be obtained by mixing an epoxy resin, a curing agent, an inorganic filler, bismuth hydroxide or bicarbonate, a phosphazene compound and other additives in a predetermined composition ratio, And then melt-mixed by heat roll, kneader, extruder or the like, followed by cooling and solidification, and pulverized into an appropriate size to obtain a molding material.

The epoxy resin composition for semiconductor encapsulation of the present invention thus obtained can be effectively used for sealing various semiconductor devices. In this case, the most common method of sealing is a low-pressure transfer molding method. The molding temperature of the epoxy resin composition for semiconductor encapsulation of the present invention is preferably 30 to 180 seconds at 150 to 180 占 폚 and 2 to 16 hours at 150 to 180 占 폚.

<Examples>

Hereinafter, examples and comparative examples of the epoxy resin composition are shown and the present invention is specifically shown, but the present invention is not limited to the following examples.

[Synthesis Example A]

4.8 g (119 mmol) of sodium hydride (NaOH) was suspended in 50 ml of tetrahydrofuran (THF) at 0 占 폚 in a nitrogen atmosphere, and thereto were added 10.2 g (108 mmol) of phenol and 4,4'-sulfonyldiphenol 0.45 g (1.8 mmol) of a 50 ml THF solution was added dropwise. After stirring for 30 minutes, a solution of 12.5 g (36.0 mmol) of hexachlorotrifosphene in 50 ml of THF was added dropwise and refluxed for 5 hours. Separately, 5.2 g (130 mmol) of sodium hydride was suspended in 50 ml of THF at 0 ° C, and 50 ml of a THF solution of 11.2 g (119 mmol) of phenol was added dropwise thereto and refluxed for another 19 hours. The solvent was distilled off under reduced pressure, and chlorobenzene was added to dissolve. The solution was extracted with 200 ml of a 5 mass% NaOH aqueous solution, 200 ml of a 5 mass% sulfuric acid aqueous solution, 2 200 ml of a 5 mass% aqueous sodium hydrogencarbonate solution, . The solvent was distilled off under reduced pressure to obtain 20.4 g of a phosphazene compound A (phosphorus atom content: 13.36 mass%) represented by the following formula.

[Examples 1 to 5, Comparative Examples 1 to 7]

The components shown in Tables 1 and 2 were uniformly melted and mixed by a thermal biaxial roll, cooled and pulverized to obtain an epoxy resin composition for semiconductor encapsulation. Using this composition, the following various characteristics of (i) to (iv) were measured, and the results are shown in Tables 1 and 2.

(i) Flammability

Based on the UL-94 standard, the flame retardancy of a 1/16 inch thick plate was investigated. The 1/16 inch thick plate was produced by molding under the conditions of a temperature of 175 DEG C, a molding pressure of 6.9 N / mm &lt; 2 &gt; and a molding time of 120 seconds and curing at 180 DEG C for 4 hours.

(ii) High-temperature storage Cu / Ag plating Adhesion to lead frame

The epoxy resin composition was molded into a 100pin-QFP frame (Cu alloy C7025, die pad part Ag plating) under the conditions of a temperature of 175 ° C, a molding pressure of 6.9N / mm 2 and a molding time of 120 seconds and curing at 180 ° C for 4 hours. Package size 14 x 20 x 2.7 mm. Twenty of these packages were stored in a 250 ° C atmosphere for 96 hours, and then the presence or absence of peeling was examined using an ultrasonic probe. The defect was found to be peeling at an area of 20% or more, and the defective number was examined.

(iii) Cu wire high temperature reliability

A 7 x 7 mm silicon chip having an aluminum wiring formed thereon was adhered to a 100pin-QFP frame (Cu alloy C7025, plated with a die pad part Ag), and the aluminum electrode and the lead frame on the chip surface were bonded with a Cu wire After wire bonding, the epoxy resin composition was molded under the conditions of a temperature of 175 캜, a molding pressure of 6.9 N / mm 2, and a molding time of 120 seconds, followed by curing at 180 캜 for 4 hours. Package size 14 x 20 x 2.7 mm. Twenty of these packages were allowed to stand in an atmosphere at 200 캜 for 1,000 hours, and then the resistance value was measured. When the resistance value was 10 times or more the initial value, the number of defects was determined.

(iv) Cu wire package, moisture resistance reliability

A 7 x 7 mm silicon chip having an aluminum wiring formed thereon was adhered to a 100pin-QFP frame (Cu alloy C7025, plated with a die pad part Ag), and the aluminum electrode and the lead frame on the chip surface were bonded with a Cu wire After wire bonding, the epoxy resin composition was molded under the conditions of a temperature of 175 캜, a molding pressure of 6.9 N / mm 2, and a molding time of 120 seconds, followed by curing at 180 캜 for 4 hours. Package size 14 x 20 x 2.7 mm. Twenty of these packages were allowed to stand in an atmosphere of 130 DEG C and 85% RH for 1,000 hours, and then the resistance value was measured. The number of defective parts was determined to be 10 times or more of the initial value.

Epoxy resin 1: o-cresol novolac epoxy resin, Epiclon N-665-EXP-S (manufactured by DIC, epoxy equivalent 200)

Epoxy resin 2: Epoxy resin represented by the following formula (2), EPPN-502H (epoxy equivalent 168, 500 ppm of hydrolyzable chlorine, 1 ppm of sodium, 1 ppm of potassium)

(Wherein a is an integer of 1 to 10)

Curing agent: phenol novolak resin, DL-92 (Meiwagase, phenolic hydroxyl equivalent of 110, sodium amount 1 ppm, potassium amount 1 ppm)

Inorganic filler: spherical fused silica (made by Tatsumori, average particle diameter 20 탆)

Bismuth hydroxide (Nippon Kayaku Co., Ltd., nitrate ion amount: 6.0% by mass)

Bismuth carbonate (Nippon Kayaku Co., Ltd., amount of nitric acid ions: 0.5% by mass)

Phosphazene compound: The phosphazene compound A obtained in Synthesis Example A

Bismuth oxide (Wako Pure Chemical Industries)

Bismuth-based inorganic ion exchanger: IXE-500 (Doogose now)

Antimony trioxide: PATOX CZ (Nippon Seisuke)

Aluminum hydroxide: Higilit 320I (Showa Denko)

Aluminum oxide: AO-41R (made by Admatex)

Hydrotalcite: DHT-4A-2 (manufactured by Kyowa Chemical Industry Co., Ltd.)

Curing accelerator: triphenylphosphine (available from Hokko Chemical)

Release agent: Carnauba wax (manufactured by Nikko Pine Products)

Carbon black: Denka black (manufactured by Denki Kagaku Kogyo)

Silane coupling agent 1: KBM-403,? -Glycidoxypropyltrimethoxysilane (manufactured by Shinetsu Chemical Industry Co., Ltd.)

Silane coupling agent 2: KBM-803P,? -Mercaptopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.)

As apparent from the results of Tables 1 and 2, the semiconductor device molded with a cured product of the epoxy resin composition for semiconductor encapsulation of the present invention has excellent adhesion with CuLF or Ag plating even when stored for a long period at a high temperature, Wire, and Cu wire / Al pads. Thus, reliability is excellent.

Furthermore, since the resin composition does not contain an antimony compound such as a brominated epoxy resin or an antimony trioxide, there is no adverse effect on the human body and the environment.

Claims (5)

(A) an epoxy resin,
(B) a curing agent,
(C) an inorganic filler,
(D) bismuth hydroxide or bismuth carbonate,
(E) a phosphazene compound represented by the following average composition formula (1)

Wherein X is a single bond or a group selected from CH ₂ , C (CH ₃ ) ₂ , SO ₂ , S, O and O (CO) O, and d, e and n satisfy 0≤d≤0.25n , 0? E <2n, 2d + e = 2n, 3? N?
, And is substantially free of bromide, phosphoric acid, phosphoric acid ester and antimony compound. The epoxy resin composition according to claim 1, wherein the amount of bismuth hydroxide or bismuth carbonate (D) is 3 to 10 parts by mass based on 100 parts by mass of the total of the components (A) and (B). 3. The epoxy resin composition according to claim 1 or 2, wherein the epoxy equivalent (A) of the epoxy resin is less than 210. The epoxy resin composition according to claim 1 or 2, wherein (A) the epoxy resin is an epoxy resin represented by the following general formula (2).

(Wherein a is an integer of 1 to 10) A semiconductor device encapsulated with a cured product of the epoxy resin composition according to any one of claims 1 to 3.