JP2007043198A - Die bonding film type adhesive, method using adhesive for manufacturing semiconductor device, and semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a die attach film for attaching a film, which functions as a die bonding adhesive, a die attach film, and a dicing film, onto a wafer under mild climate condition of 60°C or below in a fabrication step of a semiconductor. <P>SOLUTION: Peel strength of a wafer and a film-shaped adhesive is 50 g/25 mm or more when the film-shaped adhesive is attached to the rear face of the wafer at a temperature of 60°C, and preferably glass transition temperature of constituting resin composite is not less than -30°C and not more than 60°C. The resin composite is a die bonding film-shaped adhesive containing epoxy resin and acrylic acid copolymer with glass transition temperature not less than -30°C and not more than 60°C. In addition, by using a transparent substrate, a die attach film with a dicing sheet function can be manufactured. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a film adhesive for die bonding, a method for manufacturing a semiconductor device using the same, and a semiconductor device.

  In response to the recent increase in functionality of electronic devices and expansion to mobile applications, there is an increasing demand for higher density and higher integration of semiconductor devices, and IC packages are increasing in capacity and density. As a manufacturing method of these semiconductor devices, an adhesive sheet is attached to a semiconductor wafer made of silicon, gallium, arsenic, etc., and after cutting and separating into individual semiconductor elements by dicing, expanding, picking up individual chips, Next, the semiconductor chip is transferred to an assembly process of a semiconductor device in which a semiconductor chip is die-bonded to a metal lead frame, a tape substrate, or an organic hard substrate.

  The picked-up semiconductor chip is bonded to a lead frame or a substrate through a die attach material such as a liquid epoxy adhesive in a die bonding process, and a semiconductor device is manufactured. However, wafers are becoming thinner due to the necessity of stacking chips in multiple stages, but it is difficult to apply an appropriate amount of adhesive in the case of resin paste, which is a conventional die bonding material, and the adhesive may protrude from the chip. Further, there is a problem that reliability at the time of incorporation in the package is lowered due to warpage of the chip after curing. Also, the adhesive application process is complicated, and improvements and improvements are required in order to simplify the process.

  In order to solve this problem, it has been proposed to use a film adhesive as a die attach material instead of a liquid die attach material, and some of them have already been used (for example, see Patent Documents 1 and 2). . In addition, when the die attach material is attached to the back surface of the wafer, heat of 100 ° C. or higher is required, and a thin wafer having a thickness of 100 μm or less is warped or cracked.

JP 2002-353252 A (all pages) JP 2002-294177 A (all pages)

  The object of the present invention is to have a function as a dicing sheet excellent in chipping resistance and cracking characteristics, and can be used as an adhesive during die mounting, and also has uniform thickness, adhesive strength, and shear strength characteristics. The present invention is to provide a die attach film excellent in reflow resistance that can withstand severe wet heat conditions, a semiconductor device manufacturing method using the die attach film, and a semiconductor device, and a film capable of being attached at a low temperature constituting the die attach film. It is to provide an adhesive.

The present invention
(1) A film-like adhesive for die bonding, wherein the peel strength between the wafer and the film-like adhesive when the film-like adhesive is attached to the back surface of the wafer at 60 ° C. is 50 g / 25 mm or more,
(2) The film-like adhesive for die bonding according to (1), wherein the glass transition temperature of the resin composition constituting the film-like adhesive is -30 ° C or higher and 60 ° C or lower,
(3) Item (1) or (2), wherein the resin composition constituting the film adhesive comprises an acrylic acid copolymer having a glass transition temperature of -30 ° C to 60 ° C and an epoxy resin. Film adhesive for die bonding,
(4) The film adhesive for die bonding according to (3), wherein the acrylic acid copolymer has a molecular weight of 100,000 or more,
(5) The film-like adhesive for die bonding according to (3) or (4), wherein the acrylic acid copolymer is an acrylic acid copolymer containing a nitrile group,
(6) A die attach film with a dicing sheet function comprising the film adhesive for die bonding according to any one of (1) to (5) and a light-transmitting substrate,
(7) (A) A step of bonding the back surface of the silicon wafer to the die attach film with a dicing sheet function described in (6) at 60 ° C. or lower,
(B) A step of dicing the silicon wafer and separating it into individual dies,
(C) a step of irradiating the die attach film surface with ultraviolet light after dicing to cure the contact interface between the adhesive layer and the light-transmitting substrate;
(D) a pick-up process in which the die having the adhesive layer remaining on the back surface is peeled off from the light-transmitting substrate after the adhesive layer is UV-cured;
(E) a method of manufacturing a semiconductor device comprising the step of heat-bonding the die to a lead frame or a substrate via an adhesive,
(8) A semiconductor device obtained by bonding a semiconductor element and a lead frame or a substrate with the film-like adhesive for die bonding according to any one of (1) to (5).

  According to the present invention, it has excellent thickness uniformity, adhesive strength, and shear strength characteristics, and functions as a dicing sheet that is excellent in chipping resistance and crack characteristics as a dicing film when a wafer is pasted at a temperature of 60 ° C. or less. A semiconductor device using this material has an impact resistance and heat resistance equivalent to or higher than those of conventional liquid epoxy die attach materials.

  The present invention is a film-like adhesive for die bonding in which a peel strength between a wafer and a film-like adhesive is 50 g / 25 mm or more when pasted on a wafer back surface at 60 ° C. When the peel strength is less than 50 g / 25 mm, the adhesion to the wafer is weak, and chip scattering occurs during the dicing process, which is not preferable.

It is preferable that the glass transition temperature of the resin composition which comprises the film adhesive of this invention is -30 degreeC or more and 60 degrees C or less. When the glass transition temperature exceeds 60 ° C., the sticking property at 60 ° C. or less becomes difficult, and when it falls below −30 ° C., the tack property is too strong and the handling property is deteriorated.
It is preferable that the resin composition which comprises the film adhesive of this invention contains the acrylic acid copolymer whose glass transition temperature is -30 degreeC or more and 60 degrees C or less, and an epoxy resin.
As a glass transition temperature of the acrylic acid copolymer used for this invention, -30 degreeC or more and 60 degrees C or less are preferable. When the glass transition temperature is below -30 ° C, tackiness is too strong and handling becomes difficult, and when it exceeds 60 ° C, the sticking property at 60 ° C or less is deteriorated.

  Examples of the acrylic acid copolymer used in the present invention include a copolymer containing at least one of acrylic acid, acrylic acid ester, methacrylic acid ester, and acrylonitrile as a monomer component. Among them, glycidyl methacrylate having a glycidyl ether group, A copolymer containing a hydroxy methacrylate having a hydroxyl group and a carboxy methacrylate having a carboxyl group is preferred.

The molecular weight of these acrylic acid copolymers is preferably 100,000 or more, and more preferably 150,000 to 1,000,000 from the viewpoint of increasing the cohesive force.
Moreover, it is preferable that the acrylic acid copolymer used for this invention contains a nitrile group.
The epoxy resin used in the present invention refers to monomers, oligomers and polymers in general. For example, biphenyl type epoxy resin, bisphenol type epoxy resin, stilbene type epoxy resin, orthocresol novolac type epoxy resin, phenol novolac type epoxy resin, triphenolmethane type epoxy resin, alkyl-modified triphenolmethane type epoxy resin, triazine nucleus-containing epoxy resin And dicyclopentadiene-modified phenol type epoxy resin, and the like. These may be used alone or in combination.

Among these epoxy resins, crystalline epoxy resins having a melting point of 50 to 150 ° C. are preferable. Such a crystalline epoxy resin has a rigid structure such as a biphenyl skeleton, a bisphenol skeleton, and a stilbene skeleton in the main chain, and exhibits a crystallinity because of its relatively low molecular weight. A crystalline epoxy resin is a solid crystallized at room temperature, but rapidly melts into a low-viscosity liquid in a temperature range above the melting point. The melting point of the crystalline epoxy resin indicates the apex temperature of the endothermic peak of crystal melting, which is heated from room temperature at a heating rate of 5 ° C./min using a differential scanning calorimeter.
The compounding quantity of the epoxy resin used for this invention is 10-100 weight part of epoxy resins with respect to 100 weight part of acrylic acid copolymers, Preferably it is 30-70 weight part.

The resin composition constituting the film adhesive of the present invention may contain an organic compound having a cyanate group. Examples of the organic compound having a cyanate group include bisphenol A dicyanate, bisphenol F dicyanate, bis (4-cyanate phenyl) ether, and bisphenol E dicyanate cyanate novolak resin.

  The resin composition constituting the film adhesive of the present invention may contain a phenol resin. In this case, the phenol resin acts as a curing agent for the epoxy resin.

  Examples of the phenol resin used in the present invention include bis (4-hydroxy-3,5-dimethylphenyl) methane (common name: tetramethylbisphenol F), 4,4′-sulfonyldiphenol, and 4,4′-isopropylidenediphenol ( Commonly known as bisphenol A), bis (4-hydroxyphenyl) methane, bis (2-hydroxyphenyl) methane, (2-hydroxyphenyl) (4-hydroxyphenyl) methane and bis (4-hydroxyphenyl) methane, bis Bisphenols such as (2-hydroxyphenyl) methane and (2-hydroxyphenyl) (4-hydroxyphenyl) methane, a mixture of three kinds (for example, bisphenol FD manufactured by Honshu Chemical Industry Co., Ltd.), 2-benzenediol, 1,3-benzenediol, 1,4-benzene Dihydroxybenzenes such as Zendiol, trihydroxybenzenes such as 1,2,4-benzenetriol, various isomers of dihydroxynaphthalene such as 1,6-dihydroxynaphthalene, 2,2′-biphenol, 4,4′- Examples include compounds such as various isomers of biphenols such as biphenol.

The resin composition constituting the film adhesive of the present invention may contain an ultraviolet curable resin, and the ultraviolet curable resin is preferably an acrylic compound (C-1). Examples include acrylic acid or methacrylic acid ester monomers. Among them, ethylene glycol diacrylate, ethylene glycol dimethacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, glycerol diacrylate, glycerol dimethacrylate, 1,10-decanediol diacrylate, dimethacrylate Bifunctional acrylates such as acid 1,10-decanediol, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, dipentaerythritol hexaacrylate, dipentaerythritol hexamethacrylate And other polyfunctional acrylates. Of these, alkyl esters are preferable, and acrylic acid and methacrylic acid alkyl esters having 1 to 15 carbon atoms in the ester moiety are particularly preferable.

  The content of component units derived from acrylic acid or methacrylic acid ester which is an ultraviolet curable resin used in the present invention is usually 20 to 55 parts by weight, preferably 30 to 100 parts by weight with respect to 100 parts by weight of acrylic acid copolymer. When the amount is less than the lower limit value of 40 parts by weight, the adhesive strength is poor, and when the upper limit value is exceeded, the adhesive force with the protective film becomes unnecessarily large.

In addition, by introducing acrylic acid or methacrylic acid ester of an ultraviolet curable resin having a hydroxyl group such as a hydroxyl group in the molecule, the adhesion to the adherend and the properties of the adhesive can be easily controlled. .
In addition, the UV curable resin is further mixed with a photopolymerization initiator (C-2), and when it is difficult to peel off from the base material, the surface of the pressure-sensitive adhesive layer is cured and easily peeled off by irradiating with UV light. It is also an important component for use as a die attach film.

  Specific examples of such photopolymerization initiator (C-2) include benzophenone, acetophenone, benzoin, benzoin isobutyl ether, methyl benzoin benzoate, benzoin benzoic acid, benzoin methyl ether, benzylfinyl sulfide, benzyl, dibenzyl. , Diacetyl and the like.

  The ultraviolet curable resin used in the present invention preferably comprises the above components (C-1) to (C-2), and the blending ratio thereof is appropriately set according to the characteristics of each component. Specifically, the component (C-2) is preferably used in an amount of 1 to 30 parts by weight, more preferably about 3 to 15 parts by weight with respect to 100 parts by weight of the component (C-1). When the amount is less than 1 part by weight, the effect of the photoinitiator is weak, and when it exceeds 30 parts by weight, the reactivity is increased and the storage stability is deteriorated.

  The film adhesive of the present invention may contain a filler, and the average particle size of the filler is preferably 0.1 to 25 μm. When the average particle size is less than 0.1 μm, the effect of filler addition is small, and when it exceeds 25 μm, the adhesive strength as a film may be reduced.

As the filler used in the film adhesive of the present invention, silver, titanium oxide, silica, mica and the like are preferable.
The content of the filler is preferably 0% to 30% by weight, and if it exceeds 30%, the film becomes brittle and adhesiveness decreases.

Further, the present invention is a die attach film with a dicing sheet function comprising the above film adhesive and a light transmissive substrate, and the adhesive layer comprising the film adhesive has tackiness even at 25 ° C. The wafer can be attached at a low temperature of 50 ° C. or lower.
Examples of the light transmissive substrate used in the present invention include polypropylene film, polyethylene film, polybutadiene film, polyvinyl chloride film, etc., and 30 to 70 parts by weight, preferably 40 to 60 parts by weight of polypropylene resin and 70. It is preferable that it is a mixture of a polystyrene block and a copolymer composed of a vinyl isoprene block of -30 parts by weight, preferably 60-40 parts by weight.
The film thickness of the light transmissive substrate used in the present invention is preferably 20 to 200 μm, particularly preferably 25 to 150 μm.

  In the present invention, the resin composition used for the film adhesive has a sufficient adhesiveness when uncured, includes a component that is cured by irradiating ultraviolet rays of 370 nm or less, and is cured by irradiation with ultraviolet rays. It is preferable to have a feature that it does not have tackiness at the interface between the adhesive and the adherend.

  As a method for producing a die attach film with a dicing sheet function of the present invention, first, a resin composition constituting a film adhesive is varnished on a release sheet, and is generally known as a comma coater, a die coater, a gravure coater, etc. According to the method, coating and drying are performed to form an adhesive layer. Thereafter, the release sheet is removed to obtain an adhesive film, which is laminated on a light-transmitting substrate, and further, a protective film is laminated on the adhesive film, and the protective film, the adhesive layer, and the light are laminated. A die attach film having a dicing sheet function made of a permeable substrate can be obtained.

Alternatively, a dicing sheet comprising a protective film (release sheet), an adhesive layer, and a light-transmitting substrate, laminated on a light-transmitting substrate on an adhesive layer formed on the release sheet. A die attach film with a function can be obtained.
Alternatively, the resin composition constituting the film adhesive is directly coated on the light-transmitting substrate by the same method, dried, and a protective film is laminated on the film adhesive to form a protective film and a viscous film. The die attach film with a dicing sheet function which consists of an adhesive layer and a light-transmitting substrate can be obtained.
The thickness of the adhesive layer thus formed is preferably 3 to 100 μm, and more preferably 10 to 75 μm. When the thickness is less than 3 μm, the effect as an adhesive is reduced, and when it exceeds 100 μm, it is difficult to produce a product and the thickness accuracy is deteriorated.

  In the method for producing a semiconductor device of the present invention, first, the adhesive layer of the die attach film with a dicing sheet function of the present invention is attached to the back surface of the silicon wafer at room temperature or under a mild condition of 60 ° C. or less, and then the die attach film. A silicon wafer with a die attach film is fixed on a dicing apparatus via a dicing film as a dicing film, and the above silicon wafer with a die attach film is cut into individual pieces by using a cutting means such as a dicing saw. A die semiconductor chip is obtained.

Subsequently, ultraviolet light (center wavelength = about 365 nm) is irradiated onto the light-transmitting substrate surface of the die attach film attached to the semiconductor chip obtained as described above. Usually, the illuminance is set to 20 to 500 mJ / cm ² and the irradiation time is set to a range of 5 to 600 seconds. Various conditions can be set according to the case of the above-mentioned ultraviolet irradiation.
Next, only the light-transmitting substrate is peeled off while the die attach film remains fixed on the back surface of the semiconductor chip.

In this way, the semiconductor chip to which the adhesive layer of the die attach film is fixed can be die-bonded by heating and press-bonding it directly to the metal lead frame or substrate via the adhesive layer. it can. The heating and pressure bonding conditions are usually a heating temperature of 100 to 300 ° C., a pressure bonding time of 1 to 10 seconds, preferably a heating of 100 to 200 ° C. and a pressure bonding time of 1 to 5 seconds. Subsequently, by heating, the epoxy resin in the die attach film is cured, and a semiconductor device in which the semiconductor chip and the lead frame, the substrate, etc. are firmly bonded can be obtained. The heating temperature in this case is usually about 100 to 300 ° C, preferably about 150 to 250 ° C, and the heating time is usually 1 to 240 minutes, preferably 10 to 60 minutes.
The finally cured die attach film has high heat resistance, and because of the acrylic rubber resin component, the cured product has low brittleness, excellent shear strength, high impact resistance, and heat resistance.

Examples of the present invention will be described below, but the present invention is not limited to these examples.
(A) Acrylic acid copolymer resin component or polyimide resin (A-1) Epoxy group-containing acrylic rubber (manufactured by Nagase ChemteX Corporation, trade name: SG80HDR, Tg: 10 ° C., molecular weight Mw = 350,000)
(A-2) Epoxy group-containing acrylic rubber (manufactured by Nagase ChemteX Corporation, trade name: SGP3DR, Tg: 12 ° C., molecular weight Mw = 850000)
(A-3) Silicone-modified polyimide resin:
2,2-bis [4- (4-aminophenoxy) phenyl] propane (0.15 mol) and α, ω-bis (3-aminopropyl) polydimethylsiloxane (average molecular weight 837) (0.15) as diamine components Mol), a polyimide resin soluble in anisole using 4,4′-oxydiphthalic dianhydride (0.15 mol) 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride as an acid component. Tg: 100 ° C., molecular weight Mw = 50000.

(B) Resin component containing epoxy group (B-1) Cresol novolac epoxy resin (trade name: EOCN-1020-80, epoxy equivalent: 200 g / eq, manufacturer: Nippon Kayaku Co., Ltd.)
(C) UV curable resin [(C-1) (meth) acrylic acid ester monomer] 1,6-hexanediol dimethacrylate (manufacturer: Kyoeisha Chemical Co., Ltd.)
[(C-2) Photopolymerization initiator] 2,2-dimethoxyx-1,2-diphenylethane-1-one (Manufacturer: Ciba-Gigi Co., Ltd.)
(D) Filler (D-1) Silica filler SP-4B (average particle size 4 μm) (Manufacturer: Fuso Chemical Co., Ltd.)
(E) Imidazole (E-1) Imidazole compound (trade name: 1B2MZ, manufacturer: Shikoku Chemicals)

Light transmissive substrate A Hi-Bra 60 parts by weight Cleartec CT-H817 (made by Kuraray) consisting of 40 parts by weight of polypropylene was used to form a film having a thickness of 100 μm using an extruder.

Example 1
Each component was prepared at the ratio shown in Table 1 to obtain a resin composition. This resin composition was applied to a polyethylene terephthalate substrate 100 μm and dried to obtain a film adhesive. A die attach film with a dicing sheet function made of a protective film (polyethylene terephthalate substrate), a film adhesive, and a light transmissive substrate is prepared by laminating a light transmissive substrate together with this film adhesive. did.

After the protective film of the die attach film is peeled off, a semiconductor wafer is attached to the adhesive surface, fixed and held, using a dicing saw, at a spindle rotation speed of 50,000 rpm, a cutting speed of 50 mm / sec, and a 5 × 5 mm square. Cut to chip size. Next, after irradiating UV light with an integrated light amount of 250 mJ / cm ² in 20 seconds, the light-transmitting base material is peeled off from the remaining semiconductor chip on the die attach film, and then the semiconductor chip is passed through a film adhesive. It crimped | bonded to the lead frame of 42-alloy alloy on the conditions of 180 degreeC-1MPa-1.0sec, it die-bonded, and evaluated each item as a dicing sheet and a die attach film. The results are shown in Tables 2 and 3.

Example 2
The same operation as in Example 1 was performed except that the blending ratio of the adhesive component was changed as shown in Table 1.

<< Comparative Example 1 >>
The blending ratio of the adhesive component was changed as shown in Table 1. This system was not tacky and could not be laminated to a light transmissive substrate, so evaluation after dicing was not performed.

The following evaluation methods were used for evaluation of Examples and Comparative Examples.
(1) Glass transition temperature Relaxation peak when dynamic viscoelasticity of a film adhesive is measured at a temperature rising rate of 3 ° C./min and a frequency of 10 Hz using a dynamic viscoelastic device manufactured by Seiko Instruments Inc.
(2) Peel Strength Measurement Examples 1 and 2 Comparative Example 1: A die attach film with a 25 mm wide dicing sheet function was pressed at 0.1 MPa on the back side of a 5-inch 100 μm wafer and attached at 50 ° C. to measure the peel strength.

(3) Wafer warpage measurement Examples 1, 2: A die attach film with a dicing sheet function is pressurized to 0.1 MPa on the back surface of a 5-inch 100 μm wafer and bonded at 25 ° C., and the warpage of the wafer is made by Tokyo Seimitsu Co., Ltd. It was measured with a roughness profile measuring machine.
Comparative Example 1: A die attach film with a carrier film was pressurized to 0.15 MPa on the back of a 5-inch 100 μm wafer and heated at 150 ° C. to prepare a wafer with a die attach film, and the warpage of the wafer was measured.

(4) Spattering of chips after dicing After the semiconductor wafer was diced, it was evaluated by measuring the number of semiconductor chips peeled off from the die attach film due to weak adhesion.
(5) Chipping characteristics ○: The chip has a maximum width of 30 μm or less.
(Triangle | delta): The width | variety of a chip | tip hook is 30-50 micrometers at maximum.
×: The width of the chip is 50 μm or more at maximum.

(6) Pickup property It was evaluated whether a semiconductor chip with a die attach film could be picked up from a light-transmitting substrate (pickup) by irradiating ultraviolet rays after dicing the semiconductor wafer.
○: Capable of picking up almost all chips Δ: Capable of picking up 50 to 90% of diced chips ×: Picking up of 50% or less (7) Initial adhesiveness as a die attach film With die attach film The semiconductor chip was die-bonded to a 42-alloy alloy lead frame under the conditions of 180 ° C.-1 MPa-1.0 sec, and the shear strength between the chip and the lead frame was measured and evaluated in an untreated state.

(8) Adhesiveness after moisture absorption The measurement sample die-bonded in the above (7) was subjected to moisture absorption treatment at 85 ° C / 85% RH / 168 hours, and then the shear strength between the chip and the lead frame was measured and evaluated.
○: Shear strength is 1 MPa or more Δ: Shear strength is 0.5 to 1.0 MPa
X: Shear strength is less than 0.5 MPa

Claims (8)

A film-like adhesive for die bonding, wherein the peel strength between the wafer and the film-like adhesive when the film-like adhesive is attached to the back surface of the wafer at 60 ° C. is 50 g / 25 mm or more. The film adhesive for die bonding according to claim 1, wherein the glass transition temperature of the resin composition constituting the film adhesive is -30 ° C or higher and 60 ° C or lower. The film composition for die bonding according to claim 1 or 2, wherein the resin composition constituting the film adhesive comprises an acrylic acid copolymer having a glass transition temperature of -30 ° C to 60 ° C and an epoxy resin. adhesive. 4. The film adhesive for die bonding according to claim 3, wherein the acrylic acid copolymer has a molecular weight of 100,000 or more. The film adhesive for die bonding according to claim 3 or 4, wherein the acrylic acid copolymer is an acrylic acid copolymer containing a nitrile group. The die-attach film with a dicing sheet function which consists of the film adhesive for die bonding of any one of Claims 1-5, and a light-transmitting base material. (A) The process of bonding a silicon wafer back surface with the die attach film with a dicing sheet function of Claim 6 at 60 degrees C or less,
(B) A step of dicing the silicon wafer and separating it into individual dies,
(C) a step of irradiating the die attach film surface with ultraviolet light after dicing to cure the contact interface between the adhesive layer and the light-transmitting substrate;
(D) a pick-up process in which the die having the adhesive layer remaining on the back surface is peeled off from the light-transmitting substrate after the adhesive layer is UV-cured;
(E) A method of manufacturing a semiconductor device, comprising the step of heat-bonding the die to a lead frame or a substrate via an adhesive. A semiconductor device formed by bonding a semiconductor element and a lead frame or a substrate with the film-like adhesive for die bonding according to claim 1.