JP5444738B2 - Semiconductor device - Google Patents

Description

  The present invention relates to a semiconductor device.

  As a method for bonding a semiconductor element such as an IC to a metal frame, an organic substrate, or the like, a semiconductor adhesive is generally used. In recent years, it has been necessary to change the solder reflow temperature from 220 to 245 ° C. to 260 to 270 ° C. in order to remove and eliminate lead from solder used when mounting a semiconductor device on a substrate or the like as part of environmental measures. Adhesives for use are increasingly required to be resistant to an increase in thermal stress that occurs with an increase in solder reflow temperature (see Patent Document 1).

JP 2001-345331 A

  An object of the present invention is to provide a semiconductor device having excellent reflow resistance.

Such an object is achieved by the present invention described in the following (1) to (7).
(1) A semiconductor device in which a semiconductor component and a support are bonded with an adhesive, wherein the adhesive satisfies the following relationship.
A silicon chip having an area of 49 [mm ² ], a thickness of 350 [μm], an elastic modulus of 131 [GPa] at 260 ° C., a thermal expansion coefficient of 3.0 [ppm / K] at 260 ° C., and a Poisson's ratio of 0.28; , Area 90.25 [mm ² ], thickness 155 [μm], elastic modulus at 260 ° C. 127 [GPa], coefficient of thermal expansion at 260 ° C. 17.0 [ppm / K], Poisson's ratio 0.343 The copper product calculated using the elastic modulus (A) of the adhesive converted from the amount of warpage of the laminate obtained by bonding the copper lead frame with the adhesive having a thickness of 20 [μm]. The peel toughness value at 260 ° C. at the interface between the lead frame and the adhesive is 0.02 MPa · m ^1/2 or more.
(2) The semiconductor device according to (1), wherein the adhesive has a thermal expansion coefficient at 260 ° C. of 50 to 200 [ppm].
(3) The semiconductor device according to (1) or (2) above, wherein the adhesive has a saturated water absorption rate of 0.4% or less at 85 ° C. and 60% relative humidity.
(4) The adhesive according to any one of (1) to (3), wherein the adhesive is a cured product of a liquid resin composition including a compound having a radical polymerizable functional group, a curing agent, and a filler. Semiconductor device.
(5) The semiconductor device according to (4), wherein the compound having a radical polymerizable functional group is a compound having one or more functional groups selected from a (meth) acryloyl group, a maleimide group, and an allyl ester group. .
(6) The semiconductor device according to (4), wherein the curing agent includes a radical initiator.
(7) The semiconductor device according to (6), wherein the radical initiator is a compound having a decomposition temperature of 70 ° C. or higher for obtaining a half-life of 1 hour.

  According to the present invention, a semiconductor device excellent in reflow resistance can be obtained.

FIG. 1 is a cross-sectional view schematically showing an example of a semiconductor device. FIG. 2 is a cross-sectional view showing an example of an evaluation sample for evaluating the peel strength of the adhesive. FIG. 3 is a schematic diagram showing an example of a peeling strength measuring device for measuring the peeling strength of the adhesive. FIG. 4 is a diagram for explaining an analysis model used when obtaining the elastic modulus and the peel strength. FIG. 5 is a diagram for explaining an analysis result of the simulation.

Hereinafter, a semiconductor device of the present invention will be described based on preferred embodiments.
As shown in FIG. 1, in a semiconductor device 100, a semiconductor element 1 and a lead frame 2 are bonded via an adhesive 3.
The adhesive 3 satisfies the following relationship.
Adhesive 3 has an area of 49 [mm ² ], a thickness of 350 [μm], an elastic modulus of 131 [GPa] at 260 ° C., a thermal expansion coefficient of 3.0 [ppm / K] at 260 ° C., a Poisson's ratio of 0.1. 28 silicon chips, area 90.25 [mm ² ], thickness 155 [μm], elastic modulus at 260 ° C. 127 [GPa], coefficient of thermal expansion at 260 ° C. 17.0 [ppm / K], Poisson Using the elastic modulus (A) of the adhesive converted from the amount of warpage of the laminate obtained by adhering a copper lead frame having a ratio of 0.343 with the adhesive having a thickness of 20 [μm], The calculated 260 ° C. peel toughness value at the interface between the lead frame and the adhesive is 0.02 MPa · m ^1/2 or more.

When the peel toughness value at 260 ° C. obtained as described above is 0.02 MPa · m ^1/2 or more, the reflow resistance of the semiconductor device is excellent.
The reflow resistance of a semiconductor device is an evaluation of solder reflow resistance, and is generally performed as one of reliability evaluations of a semiconductor device. In this solder reflow resistance evaluation, a semiconductor element is actually fixed to a metal frame or an organic substrate with a semiconductor adhesive, and a sample packaged with a semiconductor encapsulant is absorbed under certain conditions, and then passed through a reflow furnace. The state of the adhesive for semiconductors inside the package is checked with an ultrasonic flaw detector. Since this solder reflow resistance evaluation requires time, cost, and man-hours, calculate the peel toughness value required for semiconductor adhesives from the package stress analysis, and develop an adhesive that exceeds the obtained peel toughness value. Therefore, studies have been made on alternative evaluation of solder reflow resistance evaluation. However, the correlation between the alternative evaluation result of the solder reflow resistance evaluation and the number of defects in the actual solder reflow resistance evaluation was not so high. In the conventional evaluation method, the peel toughness value was evaluated using the elastic modulus obtained by viscoelasticity measurement as the elastic modulus of the adhesive. For the measurement of the elastic modulus of the adhesive for semiconductors, a material obtained by measuring a material cured in a strip shape in an open state using a dynamic viscoelasticity measuring device or a static tensile tester was used. . However, it has been found that the elastic modulus obtained by these measurement methods is different from the elastic modulus (A) of a material that is actually cured while sandwiched between a semiconductor element, a metal frame, an organic substrate, and the like.
The present inventors have found that the elastic modulus obtained by the viscoelasticity measurement is different from the elastic modulus (A) of the material that is actually cured while being sandwiched between a semiconductor element and a metal frame, an organic substrate or the like. . And as a result of examining the evaluation method which has a correlation with the evaluation result of actual solder reflow resistance, the elastic modulus (A) obtained under the above-described conditions is used as the evaluation method of the elastic modulus (A) of the adhesive 3. When the peel toughness value at 260 ° C. was evaluated, it was found that there was a high correlation between the peel toughness value at 260 ° C. and the actual solder reflow resistance.
In the present invention, when the 260 ° C. peel toughness value at the interface between the lead frame 2 and the adhesive 3 calculated using the elastic modulus (A) of the adhesive 3 is 0.02 MPa · m ^1/2 or more. The present inventors have found that the reflow resistance of a semiconductor device is particularly excellent.
Peeling toughness of 260 ° C., more specifically preferably 0.02 MPa ^{· m 1/2} or more, particularly preferably 0.025 MPa ^{· m 1/2} or more, most 0.03 MPa ^{· m 1/2} or higher preferable. When the peel toughness value at 260 ° C. is more than the above, the solder reflow resistance is further excellent.

  In order to obtain a 260 ° C. peel toughness value using this elastic modulus (A), the above-described elastic modulus (A) and a stress intensity factor by evaluation of the peel strength of the adhesive are required. And the peeling toughness value of 260 degreeC is determined using the obtained elasticity modulus (A) and a stress intensity factor.

First, a method for evaluating the elastic modulus (A) will be described.
In order to convert the elastic modulus (A) from the warpage amount, the warpage amount at 260 ° C. and the thermal expansion coefficient of the adhesive 3 at 260 ° C. are required.
The amount of warpage was measured as follows.
Copper with an area of 90.25 [mm ² ], a thickness of 155 [μm], an elastic modulus of 127 [GPa] at 260 ° C., a thermal expansion coefficient of 17.0 [ppm / K] at 260 ° C., and a Poisson's ratio of 0.343 The adhesive 3 is applied to the central portion of the lead frame so that the thickness after curing is 20 [μm], and there is an area of 49 [mm ² ], a thickness of 350 [μm], and an elastic modulus at 260 ° C. A silicon chip having a thermal expansion coefficient of 3.0 [ppm / K] at 131 [GPa], 260 ° C. and a Poisson's ratio of 0.28 was mounted and cured in an oven.
Place the diagonal of the cured sample on the silicon chip on a hot plate at 260 ° C and measure the amount of warpage using a laser surface roughness measuring device (device name: temperature variable laser three-dimensional measuring machine (manufactured by Hitachi, Ltd.)). did. The amount of warpage was defined as the absolute value of the lowest point or the highest point when the height of both diagonals was zero.
The thermal expansion coefficient of the adhesive was measured as follows.
A cured product sample of adhesive 3 having a length of 4 [mm] × width of 4 [mm] × height of 10 [mm] is prepared, and compression TMA (apparatus name: TMA / SS120 (manufactured by Seiko Instruments Inc.)) is used. The thermal expansion coefficient of the adhesive 3 at 0 ° C. was measured.
Also, the Poisson's ratio of the adhesive is evaluated at a fixed value of 0.35 in consideration of the fact that the Poisson's ratio of the adhesive has little influence on the simulation results described later, and that it is difficult to evaluate the Poisson's ratio during heating. Went.

Then, the elastic modulus (A) was converted as follows using the amount of warpage and the coefficient of thermal expansion.
An analysis model having the same dimensions as the sample for which the amount of warpage was measured was created, and the general-purpose finite element method analysis program MSC. In Marc, the amount of warpage when the sample was 260 ° C. was calculated. At this time, the elastic modulus of the part corresponding to the adhesive 3 was varied to search for an elastic modulus value at which the predicted value of the warpage amount was within 5% of the actual measurement value. The resulting value was determined as the elastic modulus (A).

The reason why there is a high correlation between the peeling toughness value of 260 ° C. and the actual solder reflow resistance when this elastic modulus (A) is used is considered as follows.
Generally, the elastic modulus of a cured product of a semiconductor adhesive is a static elastic modulus such as Young's modulus or a dynamic elastic modulus such as a storage elastic modulus. Sample is required. Such a sample is obtained by pouring an adhesive into a mold and thermosetting it with the upper part opened. The sample obtained in this state has a large area in contact with the atmosphere. For this reason, the amount of volatile components contained in the adhesive volatilizes increases, and the elastic modulus may be estimated high. In addition, since the sample needs to have a thickness of several hundreds [μm], voids are generated inside when an adhesive is poured into the mold or during curing, and the elastic modulus may be estimated low. In particular, in the case of a radical curing adhesive, curing inhibition by oxygen occurs in curing in air, the vicinity of the open portion becomes insufficiently cured, and the elastic modulus may be estimated low. Furthermore, the curing reaction of the adhesive may change depending on the surface state of the lead frame, but it is difficult to estimate this. That is, the elastic modulus of a cured product of a conventional semiconductor adhesive such as Young's modulus and storage elastic modulus is significantly different from the elastic modulus of the adhesive in the actual use state depending on the amount of volatile matter, the presence or absence of voids, etc. Met.
On the other hand, the elastic modulus (A) used in the present invention is based on the amount of volatilization, generation of voids, inhibition of curing by oxygen, the surface condition of the lead frame, etc. It is possible to obtain the elastic modulus of the adhesive 3 in an environment close to.

Next, the evaluation of the peel strength of the adhesive for determining the stress intensity factor will be described.
First, an evaluation sample as shown in FIG. 2 is prepared.
The evaluation sample 101 is for measuring the peel strength between the adhesive 3 and the copper plate 4.
Silicon wafer 5 (length 6 mm × width 6 mm × thickness 525 μm) and copper plate 4 (length 20 mm × width 9 mm × thickness 150 μm) are bonded via adhesive 3 (length 6 mm × width 6 mm × thickness 20 μm). And glue.
At this time, a release agent is applied to a predetermined portion 31 (length 1 mm × width 6 mm) between the copper plate 4 and the adhesive 3. This predetermined portion 31 corresponds to an initial crack described later.
Next, an aluminum plate 42 (length 20 mm × width 10 mm × thickness 1 mm) is disposed on the side surface opposite to the adhesive 3 of the copper plate 4 via an adhesive 41 (Sumiresin Excel CRM-1076WA, manufactured by Sumitomo Bakelite Co., Ltd.). Glue.
Next, the glass plate 52 (length 26 mm × width 76 mm × thickness) is placed on the surface of the silicon wafer 5 opposite to the adhesive 3 via an adhesive 51 (Sumiresin Excel CRM-1076WA, manufactured by Sumitomo Bakelite Co., Ltd.). Adhesion of 1000 μm). Thus, the evaluation sample 101 for peeling strength evaluation was obtained.

The evaluation strength of this evaluation sample is evaluated using a peeling strength measuring device 102 as shown in FIG.
The glass plate 52 of the evaluation sample 101 is sandwiched between the upper mold 6 and the lower mold 7 of the apparatus 102 and fixed so as not to move. The molds (upper mold 6 and lower mold 7) are heated so that the temperature of the evaluation sample 102 becomes 260 ° C. An indenter with a width of 15 mm and a tip of 0.5φ is fixed to the top of Tensilon (RTA-100), and a position of about 9 mm from the crack tip of the copper plate 4 of the evaluation sample 101 is pushed at a moving speed of 1 mm / min. The maximum load at the time of destruction is the peel strength.

A simulation is performed using the elastic modulus (A) and peel strength of the obtained adhesive 3, and a peel toughness value of 260 ° C. is obtained by a displacement extrapolation method described below.
Next, an analysis model having the same dimensions as the sample of FIG. 4 is created, and the physical properties of the silicon chip are elastic modulus 131 [GPa] at 260 ° C., thermal expansion coefficient 3.0 [ppm / K] at 260 ° C., Poisson ratio 0.28, elastic modulus of lead frame at 260 ° C. 127 [GPa], coefficient of thermal expansion at 260 ° C. 17.0 [ppm / K], Poisson ratio 0.343, adhesive 3 at 260 ° C. By inputting the elastic modulus (A), the thermal expansion coefficient obtained by the measurement by the compression TMA and the Poisson's ratio of 0.35, the general finite element method analysis program MSC. The deformation of the sample when the above-described peeling load and a thermal stress at 260 ° C. were applied was determined at Marc.
From the obtained analysis result (FIG. 5), the component δx in which both sides of the peeling surface are shifted parallel to the peeling surface and the component δy shifted in the vertical direction are read at each node on the peeling surface, and in the plane strain approximation of Equation 1. The exfoliation toughness value was determined using displacement extrapolation (reference: Ryoji Yuki, “Interface Dynamics”, Baifukan, 1993).

The significance of obtaining the peel toughness value under such conditions will be described.
First, regarding the size of the silicon chip, the current thickness and area were selected based on the ease of mounting on a general-purpose lead frame described later and the ease of detecting the difference in adhesive. As for the thickness, if it is too thick, the amount of warpage becomes small and it becomes difficult to detect the difference between pastes.
As the lead frame, a die pad portion of a lead frame used for a general-purpose LQFP (Low Profile Quad Flat Package) was used as it was (9.5 × 9.5 mm).
In addition, the elastic modulus at 260 ° C., the expansion coefficient at 260 ° C., and the like were determined by assuming the upper limit temperature of the reflow profile of lead-free solder.

In order to achieve the 260 ° C. peeling toughness value as described above, an adhesive that can withstand deformation of the opening mode at 260 ° C. (peeling in the vertical direction of the adhesive) is required. For that purpose, it is preferable to contain a compound having a functional group capable of radical polymerization, whereby the crosslink density can be easily controlled and the elastic modulus can be easily adjusted. If the crosslinking density is too high, the cured product becomes stiff, the stress applied to the interface increases without being able to follow the deformation of the opening mode, and a very high interface adhesion is required. On the other hand, when the crosslinking density is too low, the cohesive force of the cured product is lowered, and the cured product layer is immediately destroyed with respect to the deformation of the opening mode.
An adhesive containing a compound having a functional group capable of radical polymerization can be easily adjusted in crosslink density by adjusting the number of functional groups and changing the type and amount of the radical polymerization initiator. Since the addition amount of the radical polymerization initiator is about 0.1 to 5 parts by weight, it is preferable because the viscosity of the adhesive is hardly affected even if the kind and amount are adjusted. Further, the adhesive preferably contains a filler. By adding a filler, it becomes easy to adjust the thermal expansion coefficient at 260 ° C. to a target range.

  Examples of the adhesive 3 include a film adhesive and a liquid adhesive. Among these, a liquid adhesive is preferable. Thereby, it becomes easy to add a filler, and it becomes easy to adjust the thermal expansion coefficient of 260 degreeC to the target range. Furthermore, it is excellent in that even if metal powder (especially silver powder) is added to provide conductivity and heat dissipation required for adhesives for semiconductor devices, the workability and reflow resistance of the product are small. .

The adhesive 3 is not particularly limited, but is preferably formed by applying a liquid resin composition containing a compound having a functional group capable of radical polymerization and a filler, followed by curing. Thereby, a crosslinked structure can be taken and the elasticity modulus of 260 degreeC can be improved.

Examples of the compound having a functional group capable of radical polymerization include a vinyl group and a (meth) acryloyl group. Among them, one or more functions selected from a (meth) acryloyl group, a maleimide group, and an allyl ester group are particularly preferable. Compounds having a group are preferred. By adjusting the type and amount of peroxides that are these compounds and radical initiators, the cross-linking reaction between polymers can be adjusted, and the cross-linking density can be controlled more easily than the reaction between epoxy resins and phenol derivatives. This is because a cured product obtained can be obtained.
Moreover, it is preferable to use together with the compound which has a radically polymerizable functional group, and thermosetting resins, such as an epoxy resin. Thereby, it is excellent in balance, such as sclerosis | hardenability, workability | operativity, and reflow resistance.

  Examples of the compound having the (meth) acryloyl group include 2- (meth) acryloyloxyethyl succinic acid, 2- (meth) acryloyloxypropyl succinic acid, and 2- (meth) acryloyloxyethyl hexahydrophthalic acid. 2- (meth) acryloyloxypropyl hexahydrophthalic acid, 2- (meth) acryloyloxyethyl methyl hexahydrophthalic acid, 2- (meth) acryloyloxypropyl methyl hexahydrophthalic acid, 2- (meth) Acryloyloxyethylphthalic acid, 2- (meth) acryloyloxypropylphthalic acid, 2- (meth) acryloyloxyethyltetrahydrophthalic acid, 2- (meth) acryloyloxypropyltetrahydrophthalic acid, 2- (meth) acryloyl Roxyethylmethyltetrahydrophthalic acid, 2- (meth) a Liloyloxypropylmethyltetrahydrophthalic acid, 2-hydroxy 1,3 di (meth) acryloxypropane, tetramethylol methane tri (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2 -Hydroxybutyl (meth) acrylate glycerol di (meth) acrylate, 2-hydroxy-3- (meth) acryloyloxypropyl (meth) acrylate, 1,4-cyclohexanedimethanol mono (meth) acrylate, ethyl-α- ( Hydroxymethyl) (meth) acrylate, 4-hydroxybutyl acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, tertiary butyl (Meth) acrylate, isodecyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, isoamyl (meth) acrylate, isostearyl (meth) acrylate, behenyl ( (Meth) acrylate, 2-ethylhexyl (meth) acrylate, other alkyl (meth) acrylates, cyclohexyl (meth) acrylate, tertiary butylcyclohexyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, benzyl (meth) acrylate, phenoxy Ethyl (meth) acrylate, isobornyl (meth) acrylate, glycidyl (meth) acrylate, trimethylolpropane tri (meth) acrylate, Nkmono (meth) acrylate, zinc di (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, neopentyl glycol (meth) acrylate, trifluoroethyl (meth) acrylate, 2,2,3,3 -Tetrafluoropropyl (meth) acrylate, 2,2,3,3,4,4-hexafluorobutyl (meth) acrylate, perfluorooctyl (meth) acrylate, perfluorooctylethyl (meth) acrylate, ethylene glycol di ( (Meth) acrylate, propylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, 1, -Butanediol di (meth) acrylate, 1,10-decanediol di (meth) acrylate, tetramethylene glycol di (meth) acrylate, methoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, ethoxydiethylene glycol (meth) acrylate , Methoxy polyalkylene glycol mono (meth) acrylate, octoxy polyalkylene glycol mono (meth) acrylate, lauroxy polyalkylene glycol mono (meth) acrylate, stearoxy polyalkylene glycol mono (meth) acrylate, allyloxy polyalkylene glycol mono (Meth) acrylate, nonylphenoxy polyalkylene glycol mono (meth) acrylate, N, N′-methylenebis (meth) acrylami N, N'-ethylenebis (meth) acrylamide, 1,2-di (meth) acrylamide ethylene glycol, di (meth) acryloyloxymethyltricyclodecane, 2- (meth) acryloyloxyethyl, N- (Meth) acryloyloxyethylmaleimide, N- (meth) acryloyloxyethylhexahydrophthalimide, N- (meth) acryloyloxyethylphthalimide, n-vinyl-2-pyrrolidone, styrene derivative, α-methylstyrene derivative, (Meth) acryl-modified polybutadiene, (meth) acryl-modified polyisoprene, (meth) acryl-modified acrylic resin, and the like are exemplified, but not particularly limited.

  Moreover, the compound which has the said (meth) acryloyl group may use together the compound which has 2 or more types of (meth) acryloyl groups from points, such as sclerosis | hardenability, workability | operativity, adhesiveness, and reflow resistance. The compound having a (meth) acryloyl group may be a compound having a polyfunctional (meth) acryloyl group containing two or more functional groups in one molecule.

  Examples of the compound having a maleimide group include 1,2-bis (maleimide) ethane, 1,6-bismaleimide hexane, 4,4′-bismaleimide diphenylmethane, and 6,7-methylenedioxy-4-methyl-3. -Maleimidocoumarin, bis (3-ethyl-5-methyl-4-maleimidophenyl) methane, N, N'-1,3-phenylenedimaleimide, N, N'-1,4-phenylenedimaleimide, N- ( 1-phenyl) maleimide, N- (2,4,6-trichlorophenyl) maleimide, N- (4-aminophenyl) maleimide, N- (4-nitrophenyl) maleimide, N-benzylmaleimide, N-bromomethyl-2 , 3-dichloromaleimide, N-cyclohexylmaleimide, N-ethylmaleimide, N-methylmaleimide, N Phenylmaleimide, N-succinimidyl 3-maleimidobenzoate, N-succinimidyl 3-maleimide propyrate, N-succinimidyl 3-maleimidobutyrate, N-succinimidyl 3-maleimidohexanoate, N- [4- (2-benzimidyl) ) Phenyl] maleimide, 9-fluorenylmethyl carbonate N-succinimidyl carbonate, 2-bromobenzylsuccinimidyl carbonate, 3,3′-dithiodipropionate di (N-succinimidyl), di (N-succinimidyl carbonate), N, N, N ′, N′-tetramethyl-O— (N-succinimidyl) uronium tetrafluoroborate, N- (1,2,2,2-tetrachloroethoxycarbonyloxy) succinimide, N— (2-Chlorocarbobenzoxyoxy) succinate Imide, N- (tert-butoxycarbonyl) -O-benzyl-L-serine N-succinimidyl, N-aminosuccinimide hydrochloride, N-bromosuccinimide, N-carbobenzoxyoxysuccinimide, N-chlorosuccinic acid Imide, N-ethylsuccinimide, N-hydroxysuccinimide, N-eusuccinimide, N-phenylsuccinimide, N-succinimidyl 6- (2,4-dinitroanilino) hexanoate, N-succinimidyl 6-maleimide ) Hexanoate and the like. Among these, a bismaleimide compound having two maleimide rings in one molecule is preferable from the viewpoint of curing. The two maleimide rings may be bonded to aliphatic or aromatic hydrocarbons or alkylene groups composed of those hydrocarbons via ethers or esters.

Examples of the compound having an allyl ester group include diallyl phthalate, diallyl terephthalate, diallyl isophthalate, triallyl trimerate, diallyl malate, allyl methacrylate, and allyl acetoacetate.
The number average molecular weight of such allyl ester compounds is not particularly limited, but is preferably 500 to 10,000, and particularly preferably 500 to 8,000. When the number average molecular weight is within the above range, curing shrinkage can be particularly reduced, thereby preventing a decrease in adhesion.
Examples of the allyl ester compounds having the number average molecular weight as described above include terephthalic acid, isophthalic acid, phthalic acid, 5-norbornene-endo-2,3-dicarboxylic acid, 1,4-dicyclodicarboxylic acid, and adipic acid. And both terminal allyl ester compounds obtained by adding allyl alcohol by esterification to the terminal of a polyester synthesized from a dicarboxylic acid such as the above or a methyl ester derivative thereof and an alkylene diol having 2 to 8 carbon atoms.

  The compound having the (meth) acryloyl group, the compound having a maleimide group, or the compound having an allyl ester group is not particularly limited, but preferably does not have an aromatic ring. This is because the aromatic ring has a very rigid structure, and if it has, the cured product becomes hard and brittle, and cracks are likely to occur. Therefore, in order to solve such a problem, it is preferable to have a polyalkylene oxide in the main skeleton. In the polyalkylene oxide, an alkylene group is bonded to the repeating unit in the skeleton by an ether bond. The ether bond in this structure can give some flexibility at 260 ° C. Therefore, it is considered that the cured product of the adhesive is not fragile and the occurrence of cracks and the like is suppressed as compared with a compound having an aromatic ring.

  Although carbon number in the alkylene group contained in the repeating unit in the said polyalkylene oxide is not specifically limited, 3-6 are preferable. If the number of carbon atoms is less than 3, the water absorption characteristics of the cured product may decrease, and the adhesion necessary for reflow resistance may decrease. If the number of carbon atoms exceeds 6, the resin itself becomes too hydrophobic and the metal becomes too strong. In some cases, the adhesiveness to the resin may be reduced.

  The content of the compound having a functional group capable of radical polymerization is not particularly limited, but is preferably 2 to 25% by weight, particularly preferably 10 to 25% by weight, based on the entire liquid resin composition. When the content is within the above range, the thermal expansion coefficient at 260 ° C. can be easily within the target range.

  Examples of the thermosetting resin include an epoxy resin, a phenol resin, an unsaturated polyester resin, and a melamine resin. Among these, an epoxy resin is particularly preferable. By using these in combination with a compound having a functional group capable of radical polymerization, the balance of curability, workability, reflow resistance and the like is excellent.

When the compound having a functional group capable of radical polymerization and the thermosetting resin are used in combination, the combination ratio (weight of the compound having a functional group capable of radical polymerization / weight of the thermosetting resin) is not particularly limited. However, 90/10 to 10/90 are preferable, and 85/15 to 30/70 are particularly preferable. When the combination ratio is within the above range, the adhesion to metal is particularly excellent.

Although the said liquid resin composition is not specifically limited, It is preferable that a filler is included. This facilitates adjustment of viscosity and thixotropy and adjustment of the thermal expansion coefficient at 260 ° C.
The filler is made of metal powder such as silver, gold, nickel, iron or the like for imparting conductivity, and ceramic particles such as silica or alumina, thermosetting resin or heat are used for imparting insulation. Plastic resin particles can be used. The shape of particles generally used as a filler includes various shapes such as scales, spheres, resins, powders, etc., but the shape is not particularly limited in the present invention.

  Although content of the said filler is not specifically limited, 60 to 90 weight% of the whole said liquid resin composition is preferable, and 70 to 85 weight% is especially preferable. If the content is less than the lower limit, the viscosity and thixotropy may be too low and workability may be reduced, and if the content exceeds the upper limit, the viscosity may be too high and workability may be reduced. is there.

  The average particle diameter of the filler is not particularly limited, but is preferably 1 to 10 μm, and particularly preferably 2 to 7 μm. If the average particle size is less than the lower limit, the viscosity may be high and the adjustment of the viscosity may be difficult. If the average particle size exceeds the upper limit, the nozzle may not be able to be ejected during coating. The average particle diameter can be measured using, for example, a particle size distribution measuring apparatus using a laser diffraction / scattering method.

The liquid resin composition preferably uses a radical initiator in combination. Furthermore, the radical initiator is preferably a compound having a decomposition temperature of 70 ° C. or higher for obtaining a half-life of 1 hour. This ensures the storage stability of the adhesive at room temperature. Usually, liquid adhesives for semiconductors are required not to change in viscosity for about 24 to 48 hours at room temperature. When a radical initiator having a decomposition temperature of 70 ° C. or lower for obtaining a half-life of 1 hour is used, the viscosity of the liquid adhesive may increase within 24 hours, which is not preferable.
Examples of the radical initiator include (tert-hexyl) pivalate, (tert-butyl) -peroxypivalate, di (3,5,5-trimethylhexanoyl) peroxide, dilauroyl peroxide, 1,1, 3,3-tetramethylbutylperoxy-2-ethylhexanoate, disuccinic acid peroxide, 2,5-dimethyl-2,5-di (2-ethylhexanoylperoxy) hexane, tert-hexylperoxy- 2-ethylhexanoate, di (4-methylbenzoyl) peroxide, tert-butylperoxy-2-ethylhexanoate, dibenzoyl peroxide, 1,1-di (tert-butylperoxy) -2- Methylcyclohexane, 1,1-di (tert-hexylperoxy) -3, , 5-trimethylcyclohexane, 1,1-di (tert-hexylperoxy) cyclohexane, 1,1, -di (4,4-di- (tert-butylperoxy) cyclohexyl) propane, tert-hexylperoxyisopropyl Monocarbonate, tert-butylperoxymaleic acid, tert-butylperoxy-3,5,5-trimethylhexanoate, tert-butylperoxylaurate, tert-butylperoxyisopropylmonocarbonate, tert-butylperoxy 2-ethylhexyl monocarbonate, tert-hexyl peroxybenzoate, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, tert-butyl peroxyacetate, 2,2-di (tert-butyl peroxyacetate) Oxy) butane, tert-butylperoxybenzoate, di (2-tert-butylperoxyisopropyl) valerate, di (2-tert-butylperoxyisopropyl) benzene, dicumyl peroxide, di-tert-hexyl peroxide, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane, tert-butylcumyl peroxide, di-tert-butyl peroxide, p-menthane hydroperoxide, 2,5-dimethyl-2, 5-di (tert-butylperoxy) hexyne, diisopropylbenzene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, cumene hydroperoxide, tert-butyl hydroperoxide, tert-amylper Oxypivalate, tert-amylperoxy-2-ethylhexanoate, tert-amylperoxy-n-octate, tert-amylperoxyacetate, tert-amylperoxyisononanoate, tert-amylperoxybenzoate, tert- Examples include amylperoxyisopropyl carbonate, tert-amylperoxy-2-ethylhexyl carbonate, di-tert-amyl peroxide, 1,1-di (tert-amylperoxy) cyclohexane, tert-amyl hydroperoxide, and the like. A plurality of these may be used as necessary.

  Although content of the said radical initiator is not specifically limited, 0.1 to 10 weight% of the whole said liquid resin composition is preferable, and 0.5 to 5 weight% is especially preferable. If the content is less than the above lower limit, the amount of radical active species necessary for the polymerization is not sufficient, so that it may not be completely cured and sufficient adhesive strength may not be obtained, and the content exceeds the upper limit. The amount of radical active species generated at room temperature increases and the reaction proceeds, and the viscosity of the liquid adhesive may increase within 24 hours.

  The liquid resin composition may contain other additives such as a coupling agent, an antifoaming agent, and a surfactant as necessary.

Each component of the liquid resin composition as described above was premixed, kneaded using three rolls, and then defoamed under vacuum to obtain a liquid adhesive (paste).
The semiconductor device of the present invention is particularly excellent in reflow resistance because the semiconductor element and the support are bonded with the adhesive as described above.

Next, the manufacture of the semiconductor device will be briefly described.
The above-mentioned adhesive composition is applied to a predetermined portion of a support made of a substrate such as a lead frame or an organic substrate, for example, to form an adhesive layer. Next, after the semiconductor element is mounted on the support, the adhesive layer is heated and cured to obtain a semiconductor device in which the semiconductor element and the support are bonded with an adhesive.
Also, a semiconductor device is obtained by applying an adhesive composition to a predetermined position (for example, the upper surface of the flip chip) of the flip chip solder-bonded and sealed to the substrate, mounting the heat dissipation member, and then heating. be able to.

  The thickness of the adhesive is not particularly limited, and is 5 μm or more, 100 μm or less, preferably 10 μm or more, taking into consideration the balance between the coating workability and the adhesive properties with respect to the silver plating surface and the adhesive properties with respect to the copper surface. It is 50 μm or less, and most preferably 10 μm or more and 30 μm or less. If it is less than the lower limit, the adhesive properties may be reduced, and if the upper limit is exceeded, it may be difficult to control the thickness of the adhesive, and the balance between the adhesive properties for the silver plating surface and the copper surface may not be stable. Because there is.

Thus, a known method can be used to manufacture the semiconductor device. For example, using a commercially available die bonder, the adhesive composition is dispensed on a predetermined portion of a support such as a lead frame or a substrate or a heat dissipation member, and then the semiconductor element is mounted and cured by heating. Thereafter, wire bonding is performed, and a semiconductor device is manufactured by transfer molding using an epoxy resin. Alternatively, the adhesive composition is dispensed on the back surface of a semiconductor element such as a flip chip BGA (Ball Grid Array) sealed with an underfill material after flip chip bonding, and heat curing components such as heat spreaders and lids are mounted and cured. Usage is also possible.
Although the case where the adhesive composition is applied to a lead frame has been described, it may be applied to a semiconductor element.

  Similarly, when a film adhesive is used, the film adhesive can be attached to a lead frame or a semiconductor element.

The thermal expansion coefficient at 260 ° C. of the adhesive 3 (adhesive after curing) used in the semiconductor device 100 is not particularly limited, but is preferably 50 to 200 [ppm / K], particularly 100 to 150. [Ppm / K] is preferable. When the thermal expansion coefficient at 260 ° C. is within the above range, the solder reflow resistance is further excellent.
The thermal expansion coefficient is, for example, a cured material sample of adhesive 3 having a length of 4 [mm] × width of 4 [mm] × height of 10 [mm], and compressed TMA (device name TMA / SS120 (manufactured by Seiko Instruments Inc.). ) Can be used to measure the thermal expansion coefficient of the adhesive 3 at 260 ° C.

Further, the saturated water absorption rate of the adhesive 3 (adhesive after curing) at 85 ° C. and 60% relative humidity is not particularly limited, but is preferably 0.4% or less, particularly 0.3%. It is preferable that When the saturated water absorption is within the above range, the solder reflow resistance is further excellent.
The saturated water absorption is, for example, a cured product sample of adhesive 3 having a length of 10 [mm] × width of 10 [mm] × height of 0.1 [mm], and constant temperature and humidity of 85 ° C. and 60% relative humidity. Place in the tank and follow the time course of water absorption. The obtained water absorption change with time can be approximated to Fick's diffusion equation to obtain the saturated water absorption.

  As described above, the semiconductor device 100 of the present invention is particularly excellent in reflow resistance because the semiconductor element 1 and the lead frame 2 are bonded to each other by the adhesive 3 having the characteristics as described above. Furthermore, it has excellent temperature cycle resistance.

  In the present embodiment, the lead frame is exemplified as the support and the semiconductor element is exemplified as the semiconductor component. However, the present invention is not limited to this. Examples of the support include a substrate such as an organic substrate and an inorganic substrate, and a flip chip. Examples of the semiconductor component include a heat sink, a heat spreader, a lid, and a stiffener.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example and a comparative example, this invention is not limited to this.

Example 1
1. Preparation of Adhesive Polytetramethylene glycol di (2-maleimidoacetate) as a compound having a radical polymerizable functional group (Dainippon Ink & Chemicals, LumiCure MIA-200, hereinafter referred to as Compound 1) 8.4% by weight And allylic ester resin (Showa Denko Co., Ltd., DA-101, hereinafter Compound 2) 9.6% by weight, 1,4-cyclohexanedimethanol monoacrylate (Nippon Kasei Co., Ltd., CHDMMA, hereinafter referred to as Compound 3) 6 0.0% by weight of dicumyl peroxide (manufactured by NOF Corporation, Park Mill D, decomposition temperature 136 ° C. for obtaining a half-life of 1 hour, hereinafter, compound 4) 0.7% by weight as a radical initiator Used, 75% by weight of flaky silver powder (hereinafter referred to as silver powder) having an average particle diameter of 8 μm and a maximum particle diameter of 30 μm as a filler, and bis (t Ethoxysilylpropyl) tetrasulfide (Nihon Unicar Co., Ltd., A-1289, hereinafter Compound 5) 0.2 wt%, 3-methacryloxypropyltrimethoxysilane (Shin-Etsu Chemical Co., Ltd., KBM-503P, compound) 6) 0.1% by weight was premixed, kneaded for 30 minutes at about 25 ° C. using three rolls, and then defoamed under vacuum to obtain a liquid adhesive (paste).

In addition, the elastic modulus (A) of the obtained adhesive was 200 MPa, and the peel strength was 3.6 N. Furthermore, the 260 ° C. peel toughness value obtained by simulation using these values was 0.021 MPa · m ^1/2 .

2. Manufacturing of Semiconductor Device A semiconductor element (thickness 350 μm, size 7 × 7 mm) and a lead frame made by Shinko were joined using the above-mentioned adhesive paste, heated from room temperature to 175 ° C. in 30 minutes, and then 175 ° C. Then, the adhesive was cured by heating for 30 minutes to obtain a semiconductor device.

(Example 2)
The procedure was the same as Example 1 except that the adhesive was mixed as follows.
8.4% by weight of Compound 1 and 9.6% by weight of Compound 2, 1.2% by weight of polyethylene glycol dimethacrylate (manufactured by Kyoeisha Chemical Co., Ltd., Light Ester 4EG, hereinafter referred to as Compound 7), trimethylolpropane trimethacrylate ( Kyoeisha Chemical Co., Ltd., light ester TMP, hereinafter compound 8) 0.7% by weight, 2-methacryloyloxyethyl succinic acid (manufactured by Kyoeisha Chemical Co., Ltd., light ester HOMS, hereinafter compound 9) 0.5% by weight, Compound 3.6% by weight, compound 4 0.7% by weight, silver powder 75% by weight, compound 5 0.2% by weight, compound 6 0.1% by weight did.

(Example 3)
The procedure was the same as Example 1 except that the adhesive was mixed as follows.
As a compound having a radical polymerizable functional group, ethylene glycol dimethacrylate (manufactured by Kyoeisha Chemical Co., Ltd., light ester EG, hereinafter referred to as compound 10) 6.6% by weight, compound 4 0.5% by weight, silver powder 75% by weight %, Diglycidyl bisphenol F obtained by reaction of bisphenol F and epichlorohydrin as a thermosetting resin (Nippon Kayaku Co., Ltd., RE-403S, epoxy equivalent 160-170, hereinafter referred to as compound 11) 4.2% by weight, Diglycidyl etherified product of reaction product of polyalkylene oxide divinyl ether and bisphenol A (Dainippon Ink & Chemicals, EXA-4850-1000, epoxy equivalent 250-450, hereinafter referred to as compound 12) 4.2% by weight, 1 4-cyclohexanedimethanol diglycidyl ether (Toto Kasei) Co., Ltd., ZX-1658GS, epoxy equivalent 130-140, compound 13) 4.2% by weight, bisphenol F (manufactured by Dainippon Ink & Chemicals, Inc., DIC-BPF, hydroxyl equivalent 100, compound below) as curing agent 14) 4.2% by weight, dicyandiamide (manufactured by Asahi Denka Kogyo Co., Ltd., Adeka Hardener EH-3636AS, hereinafter compound 15) 0.3% by weight, 2-phenyl-4-methyl-5-hydroxymethylimidazole (catalyst) Shikoku Kasei Kogyo Co., Ltd., Curazole 2P4MHZ, Compound 16) 0.5 wt%, Compound 5 0.2 wt%, 3-glycidylpropyltrimethoxysilane (Shin-Etsu Chemical Co., Ltd., KBM-403E) The following compound 17) was blended using 0.1% by weight.

Example 4
The procedure was the same as Example 1 except that the adhesive was mixed as follows.
Compound 1 is 8.4 wt%, Compound 2 is 9.6 wt%, Compound 7 is 1.2 wt%, Compound 8 is 0.7 wt%, Compound 9 is 0.5 wt%, and Compound 3 is 3. 6% by weight, bis (4-t-butylcyclohexyl) peroxydicarbonate (manufactured by NOF Corporation, Parroyl TCP, decomposition temperature 56 ° C. for obtaining a half-life of 1 hour, the following compound 18 as a radical initiator ) 0.7 wt%, silver powder 75 wt%, compound 5 0.2 wt%, and compound 6 0.1 wt%.

(Example 5)
The procedure was the same as Example 1 except that the adhesive was mixed as follows.
8.0 wt% of compound 10, 0.7 wt% of compound 4, 70 wt% of silver powder, 5.0 wt% of compound 11, 5.0 wt% of compound 12, 5.0 wt% of compound 13 Compound 14 was mixed at 5.0% by weight, Compound 15 at 0.4% by weight, Compound 16 at 0.6% by weight, Compound 5 at 0.2% by weight, and Compound 17 at 0.1% by weight.

(Example 6)
The procedure was the same as Example 1 except that the adhesive was mixed as follows.
9.6% by weight of compound 10, 0.4% by weight of compound 4, 75% by weight of silver powder, 3.5% by weight of compound 11, 3.5% by weight of compound 12, and 3.5% by weight of compound 13 Compound 14 was compounded using 3.5% by weight, Compound 15 using 0.3% by weight, Compound 16 using 0.4% by weight, Compound 5 using 0.2% by weight, and Compound 17 using 0.1% by weight.

(Comparative Example 1)
The procedure was the same as Example 1 except that the adhesive was mixed as follows.
Silver powder 75% by weight, compound 11 5.9% by weight, compound 12 5.9% by weight, compound 13 5.9% by weight, compound 14 5.9% by weight, compound 15 0.5% by weight Compound 16 was compounded using 0.6% by weight, Compound 5 using 0.2% by weight, and Compound 17 using 0.1% by weight.

The semiconductor device obtained in each example and comparative example was evaluated as follows. The evaluation items are shown together with the contents. The obtained results are shown in Table 1.
1. Elastic modulus In order to evaluate the peel toughness value, the elastic modulus of the adhesive was first evaluated. As the elastic modulus, the elastic modulus (A) converted from the warp amount as already described was used. This elastic modulus (A) was measured by the method already described.

2. Peel strength In order to evaluate the peel toughness value, the peel strength was then evaluated. The peel strength was evaluated by a method as already described using a peel strength measuring apparatus 102 as shown in FIG.

3. Thermal expansion coefficient The thermal expansion coefficient at 260 ° C was evaluated in order to evaluate the peel toughness value in the same manner as the elastic modulus (A) described above. A cured product sample of adhesive 3 having a length of 4 [mm] × width of 4 [mm] × height of 10 [mm] is prepared, and compression TMA (apparatus name: TMA / SS120 (manufactured by Seiko Instruments Inc.)) is used. The thermal expansion coefficient of the adhesive 3 at 0 ° C. was measured.

4). Peel toughness value The peel toughness value was evaluated by the method (simulation) as already described using these elastic modulus (A), peel strength and the like.

5. Water absorption
A cured product sample of Adhesive 3 having a length of 10 [mm] × width of 10 [mm] × height of 0.1 [mm] is prepared and placed in a constant temperature and humidity chamber of 85 ° C. and 60% relative humidity. Follow changes over time. The obtained water absorption change with time was approximated to Fick's diffusion equation to obtain a saturated water absorption rate. Each code is as follows.
A: The saturated water absorption was 0.2% or more and less than 0.3%.
○: The saturated water absorption was 0.3% or more and less than 0.4%.
X: The saturated water absorption was 0.4% or more.

6. Viscosity change after 24 hours
The viscosity change rate after 24 hours of the obtained adhesive paste was evaluated. The viscosity change rate was measured by measuring the viscosity at 5.0 rpm of the adhesive 3 immediately after thawing using a Brookfield viscometer. Then, after leaving at 25 ° C. for 24 hours, the viscosity at 5.0 rpm was measured again, and the viscosity change rate after 24 hours was determined using the following formula.
Viscosity change rate after 24 hours = (viscosity after 24 hours−viscosity immediately after thawing) / viscosity immediately after thawing [%]

7). Reflow resistance (peeling area)
For reflow resistance, a semiconductor element was mounted on the following lead frame using each resin composition, and cured and bonded in an oven (175 ° C., 30 minutes).
The mount was adjusted using a die bonder (manufactured by ASM) so that the coating thickness was about 25 μm immediately after the resin composition was applied. The lead frame after the resin composition was cured was sealed with a sealing material (Sumicon EME-G700H, manufactured by Sumitomo Bakelite Co., Ltd.) to produce a semiconductor device. This semiconductor device was subjected to moisture absorption treatment at 85 ° C. and relative humidity 60% for 168 hours, followed by IR reflow treatment (260 ° C., 10 seconds, 3 times reflow). The degree of peeling of the treated semiconductor device was measured by an ultrasonic flaw detector (transmission type).
Semiconductor device: QFP (14 x 20 x 2.0 mm)
Lead frame: Silver-plated copper frame (silver-plated part)
Chip size: 6x6mm
Each code is as follows.
(Double-circle): There was no peeling.
○: The peeled area was less than 10%.
X: The peeled area was 10% or more.

As is clear from Table 1, Examples 1 to 6 having a peel toughness value of 0.02 MPa · m ^1/2 or more were excellent in reflow resistance.
In addition, Examples 1, 2, 3, 5 and 6 also showed a low rate of change in viscosity after 24 hours and excellent storage stability.

DESCRIPTION OF SYMBOLS 1 Semiconductor element 2 Lead frame 3 Adhesive 31 Predetermined part 4 Copper plate 41 Adhesive 42 Aluminum plate 5 Silicon wafer 51 Adhesive 52 Glass plate 6 Upper mold | type 7 Lower mold | type 100 Semiconductor device 101 Evaluation sample 102 Stripping strength measuring apparatus

Claims (4)

A semiconductor device in which a semiconductor component and a support are bonded with an adhesive,
The semiconductor component is a semiconductor element composed of a silicon chip, the support is composed of a copper lead frame, and the adhesive is applied to a predetermined portion of the support and heated in an oven. It is formed from a cured product obtained by curing, and the semiconductor device is mounted on a substrate at a reflow temperature of 260 ° C. or higher, and the liquid resin composition is selected from a (meth) acryloyl group, a maleimide group, and an allyl ester group A functional group capable of radical polymerization, comprising a compound having one or more radical polymerizable functional groups, a curing agent including a radical initiator, a filler, and bis (triethoxysilylpropyl) tetrasulfide. Is a compound having no aromatic ring,
The content of the compound having a functional group capable of radical polymerization is 2 to 25% by weight of the whole liquid resin composition,
The content of the filler is 60 to 90% by weight of the entire liquid resin composition,
The content of the radical initiator is 0.1 to 10% by weight of the whole liquid resin composition,
A semiconductor device characterized in that the adhesive satisfies the following relationship.
A silicon chip having an area of 49 [mm ² ], a thickness of 350 [μm], an elastic modulus of 131 [GPa] at 260 ° C., a thermal expansion coefficient of 3.0 [ppm / K] at 260 ° C., and a Poisson's ratio of 0.28; , Area 90.25 [mm ² ], thickness 155 [μm], elastic modulus at 260 ° C. 127 [GPa], coefficient of thermal expansion at 260 ° C. 17.0 [ppm / K], Poisson's ratio 0.343 The copper product calculated using the elastic modulus (A) of the adhesive converted from the amount of warpage of the laminate obtained by bonding the copper lead frame with the adhesive having a thickness of 20 [μm]. The peel toughness value at 260 ° C. at the interface between the lead frame and the adhesive is 0.02 MPa · m ^1/2 or more.   The semiconductor device according to claim 1, wherein a thermal expansion coefficient of the adhesive at 260 ° C. is 50 to 200 [ppm].   3. The semiconductor device according to claim 1, wherein a saturated water absorption rate of the adhesive at a temperature of 85 ° C. and a relative humidity of 60% is 0.4 [%] or less.   The semiconductor device according to claim 1, wherein the radical initiator is a compound having a decomposition temperature of 70 ° C. or higher for obtaining a half-life of 1 hour.

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