JP2001044224A - Semiconductor device and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device capable of preventing the occurrence of runner breaks immediately after transfer molding and making the operation thereafter satisfactory. SOLUTION: This semiconductor device has semiconductor elements sealed therein with a sealing resin, made of a cured body of epoxy resin composition by transfer molding. The cured body of epoxy resin composition has following characteristics (A) the cured body of epoxy resin composition has a high- temperature bending elastic modulus of 250 kg/mm2 or lower at 175 deg.C immediately after transfer-molded, and (B) the cured body of epoxy resin composition has a glass transition temperature ranging from 125 to 150 deg.C, immediately after being transfer-molded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device in which a semiconductor element is resin-sealed by a transfer molding method, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, transistors, ICs, and LSIs have been used.
Semiconductor devices such as those described above are resin-sealed with an epoxy resin composition to form a semiconductor device from the viewpoint of protection from the external environment and easy handling of the semiconductor device.

[0003] In the manufacture of semiconductor devices using the epoxy resin composition, a transfer molding method using a transfer molding machine has conventionally been used.

[0004]

As described above, a semiconductor device has been conventionally manufactured by the transfer molding method. However, in the manufacturing process, breakage of the runner occurs when the mold is opened immediately after the transfer molding. The problem had arisen. When the runner is broken, the transfer molded body composed of a plurality of molded packages cannot be taken out integrally, and there is a disadvantage that the subsequent workability is significantly deteriorated.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a semiconductor device capable of preventing occurrence of breakage of a runner immediately after transfer molding and improving workability thereafter, and a method of manufacturing the same. Aim.

[0006]

In order to achieve the above object, the present invention provides a semiconductor device in which a semiconductor element is sealed by transfer molding with a sealing resin made of a cured epoxy resin composition, A first gist is a semiconductor device in which the cured epoxy resin composition has the following properties (A) and (B). (A) The high-temperature flexural modulus at 175 ° C. immediately after transfer molding of the cured epoxy resin composition is 250 kg /
mm ² or less. (B) The glass transition temperature of the cured epoxy resin composition immediately after transfer molding is in the range of 125 to 150 ° C.

Further, the present invention is a method of manufacturing a semiconductor device by encapsulating a semiconductor element with a resin by a transfer molding method using an epoxy resin composition, wherein the epoxy resin composition is subjected to a transfer molding method. The second gist is a method of manufacturing a semiconductor device in which the loss on heating is 0.15 to 0.30% by weight and the cured body immediately after transfer molding has the following properties (A) and (B). (A) The high-temperature flexural modulus at 175 ° C. immediately after transfer molding of the cured epoxy resin composition is 250 kg /
mm ² or less. (B) The glass transition temperature of the cured epoxy resin composition immediately after transfer molding is in the range of 125 to 150 ° C.

That is, the inventor of the present invention has intensively studied to find an effective means for preventing the occurrence of breakage of the runner during transfer molding. as a result,
In a cured epoxy resin composition as a sealing resin immediately after transfer molding, a semiconductor device sealed with a cured body having a high-temperature bending elastic modulus at 175 ° C. and a glass transition temperature within the above range is obtained immediately after transfer molding. The present inventors have found that the semiconductor device can be taken out of the transfer mold without breakage of the runner when the mold is opened, and as a result, the subsequent workability is improved.

In the case where the cured epoxy resin composition is formed of an epoxy resin composition containing a cresol novolak type epoxy resin as a main component and a phenol novolak resin as a curing agent,
Excellent curability and improved productivity.

Further, when the epoxy resin composition having a specific range of loss on heating is produced as an epoxy resin composition before being subjected to transfer molding, the above-mentioned properties (A) and (B) of the epoxy resin composition cured product to be formed, Especially characteristic (A)
It has been found that it is easy to control the high temperature bending elastic modulus, and as a result, it is possible to easily obtain a good semiconductor device having the above characteristics (A) and (B).

[0011]

Next, an embodiment of the present invention will be described.

The semiconductor device of the present invention is one in which a semiconductor element is resin-sealed with a sealing resin made of a cured epoxy resin composition having specific characteristics by a transfer molding method.

The cured epoxy resin composition is formed by curing an epoxy resin composition containing an epoxy resin as a main component and a curing agent. When the epoxy resin composition is subjected to resin molding by transfer molding, it is usually supplied in the form of a powder or a tablet obtained by compressing the powder.

The epoxy resin is not particularly limited, and various conventionally known epoxy resins are used. For example, cresol novolak type epoxy resin, phenol novolak type epoxy resin, biphenyl type epoxy resin, bisphenol A type epoxy resin, naphthalene type epoxy resin and the like can be mentioned. These epoxy resins are used alone or in combination of two or more. Among them, a cresol novolak type epoxy resin is preferably used from the viewpoint of improving curability and productivity. And
In the cresol novolak type epoxy resin, it is preferable to use one having an epoxy equivalent of 150 to 250 and a softening point of 50 to 130 ° C, particularly preferably an epoxy equivalent of 180 to 210 and a softening point of 60 to 110 ° C.

As a curing agent used together with the epoxy resin, a phenol resin is usually used. The phenol resin is not particularly limited, and various conventionally known phenol resins are used.For example, novolak resins such as phenol novolak resins, phenol aralkyl resins such as xylylene-modified phenol resins,
Examples include terpene-modified phenol resins and dicyclopentadiene-modified phenol resins. These phenol resins are used alone or in combination of two or more. Among them, it is preferable to use a phenol novolak resin from the viewpoint of improving curability and productivity. In the phenol novolak resin, those having a hydroxyl equivalent of 70 to 250 and a softening point of 40 to 110 ° C. are preferably used, and particularly preferably, a hydroxyl equivalent of 90 to 11 is used.
0, softening point 50-100 ° C.

The mixing ratio of the epoxy resin and the phenol resin is preferably such that the hydroxyl group in the phenol resin is 0.8 to 1.2 equivalent per 1 equivalent of the epoxy group in the epoxy resin. More preferred is 0.
9 to 1.1 equivalents.

In the epoxy resin composition used for semiconductor encapsulation, a curing accelerator is usually used together with the epoxy resin and the curing agent. Specific examples of the curing accelerator include alkyl-substituted guanidines such as ethylguanidine, trimethylguanidine, phenylguanidine, and diphenylguanidine; 3- (3,4-dichlorophenyl) -1,1-dimethylurea; -1,
1-dimethylurea, 3- (4-chlorophenyl) -1,
3-substituted phenyl-1,1-dimethylureas such as 1-dimethylurea, imidazolines such as 2-methylimidazoline, 2-phenylimidazoline, 2-undecylimidazoline, 2-heptadecylimidazoline, 2-aminopyridine and the like Monoaminopyridines, N, N-dimethyl-
Amine imides such as N- (2-hydroxy-3-allyloxypropyl) amine-N'-lacimide, ethylphosphine, propylphosphine, butylphosphine,
Organic phosphorus compounds such as phenylphosphine, trimethylphosphine, triethylphosphine, tributylphosphine, trioctylphosphine, triphenylphosphine, tricyclohexylphosphine, triphenylphosphine / triphenylborane complex, and tetraphenylphosphonium tetraphenylborate; And diazabicyclo [5,4,0] undecene-7 and 1,4-diazabicyclo [2,2,2] octane. Among them, an organic phosphorus compound such as triphenylphosphine or an imidazole compound is suitably used. These may be used alone or in combination of two or more.

The amount of the curing accelerator is preferably set in the range of 0.1 to 0.5% by weight, particularly preferably 0.2 to 0.3% by weight, in the epoxy resin composition.

Further, an inorganic filler is used in the epoxy resin composition for semiconductor encapsulation together with the above components.
The inorganic filler is not particularly limited, and a conventionally known inorganic filler is used. For example, silica powder such as fused silica powder and crystalline silica powder, and alumina powder are used. These inorganic fillers can be used in any form such as crushed, spherical, or ground. These are used alone or in combination of two or more. And, as a whole of the inorganic filler,
Using an average particle diameter in the range of 6 to 40 μm,
It is preferable from the viewpoint of improving the fluidity. Further, among the above-mentioned inorganic fillers, it is particularly preferable to use crushed fused silica powder and spherical fused silica powder from the viewpoint of good fluidity.

The amount of the inorganic filler is preferably set so as to be 70 to 85% by weight, particularly preferably 72 to 78% by weight in the epoxy resin composition. That is, when the blending amount of the inorganic filler is less than 70% by weight,
This is because the water absorption of the package after molding increases, and the reliability at the time of mounting tends to decrease. When the amount exceeds 85% by weight, the fluidity tends to deteriorate.

Further, the epoxy resin composition for encapsulating a semiconductor may optionally contain other additives in addition to the above components, if necessary.

Examples of the other additives include a release agent, a flame retardant, a colorant, various silane coupling agents, a stress reducing agent, and the like.

Examples of the release agent include conventionally known long-chain carboxylic acids such as stearic acid and palmitic acid, metal salts of long-chain carboxylic acids such as zinc stearate and calcium stearate, polyethylene wax, carnauba wax, and the like.
Waxes such as montan wax can be used.

As the flame retardant, a halogen-based flame retardant such as a brominated epoxy resin and a flame retardant auxiliary such as antimony trioxide and antimony pentoxide can be used.

Further, in addition to the halogen-based flame retardant, a polyhedral composite metal hydroxide represented by the following general formula (1) can be used. This composite metal hydroxide has a polyhedral crystal shape and has a conventional hexagonal plate shape, or a so-called thin plate-like crystal shape such as a scale-like shape. Rather, the crystal growth in the thickness direction (c-axis direction) is large both vertically and horizontally. Crystal shape, for example, approximately dodecahedron, approximately octahedron,
A composite metal hydroxide having a shape such as a substantially tetrahedron.

[0026]

Embedded image

Regarding the composite metal hydroxide represented by the general formula (1), M representing the metal element in the formula (1) is represented by Al, Mg, Ca, Ni, Co, Sn, Zn, C
u, Fe, Ti, B and the like.

Q representing another metal element in the composite metal hydroxide represented by the general formula (1) is IVa, Va, VIa, VIIa, VIII, Ib, IIb in the periodic table. Metals belonging to the group selected from For example, Fe, C
o, Ni, Pd, Cu, Zn, etc., and are selected alone or in combination of two or more.

The composite metal hydroxide having such a polyhedral crystal shape can be obtained, for example, by controlling various conditions in the production process of the composite metal hydroxide.
Obtaining a composite metal hydroxide having a desired polyhedral shape, such as a substantially dodecahedral, a substantially octahedral, or a substantially tetrahedral shape, in which crystal growth in the thickness direction (c-axis direction) is large both vertically and horizontally. And usually consists of these mixtures.

Specific typical examples of the composite metal hydroxide having the polyhedral shape include hydrates of magnesium oxide / nickel oxide, hydrates of magnesium oxide / zinc oxide, and hydrates of magnesium oxide / copper oxide. Japanese products.

The composite metal hydroxide having the above-mentioned polyhedral shape has an aspect ratio of usually 1 to 8, preferably 1 to 8.
To 7, particularly preferably 1 to 4. The term “aspect ratio” as used herein refers to the ratio of the major axis to the minor axis of the composite metal hydroxide. That is, when the aspect ratio exceeds 8, the effect of lowering the viscosity when the epoxy resin composition containing the composite metal hydroxide is melted becomes poor. When used as a component of the epoxy resin composition for semiconductor encapsulation of the present invention, one having an aspect ratio of 1 to 4 is generally used.

Further, examples of the coloring agent include carbon black.

Examples of the various silane coupling agents include γ-glycidoxypropyltrimethoxysilane.

Examples of the low stress agent include butadiene rubbers and silicone compounds such as methyl acrylate-butadiene-styrene copolymer and methyl methacrylate-butadiene-styrene copolymer. Further, an ion trapping agent such as hydrotalcites and bismuth hydroxide may be blended for the purpose of improving the reliability in the moisture resistance reliability test.

The epoxy resin composition for semiconductor encapsulation used in the present invention can be produced, for example, as follows. That is, first, the above components are appropriately blended, and the mixture is melted and mixed in a kneading machine such as a mixing roll in a heated state, cooled to room temperature, pulverized by a known means, and tableted as necessary. It can be manufactured by a series of steps.

The epoxy resin composition thus obtained must have a loss on heating of 0.15 to 0.30% by weight before it is subjected to the subsequent transfer molding. In particular, heating loss is 0.20 to 0.25
% By weight. That is, when the weight loss on heating is less than 0.15% by weight, the high-temperature elasticity becomes high, and
If the content exceeds 30% by weight, insufficient curing and voids occur. As described above, the heating loss is a numerical value caused by the high-temperature elastic modulus, and means that the higher the heating loss, the lower the high-temperature elastic modulus. Therefore, when the heat loss is reduced, the high-temperature bending elastic modulus of the sealing resin (cured body) immediately after transfer molding is increased, and as a result, breakage of the runner is observed.

As a method for setting the heat loss of the epoxy resin composition so as to be within the above range, for example, a method of controlling the moisture content by controlling the humidity of a sealing resin made of a cured epoxy resin composition can be mentioned. .

The above-mentioned loss on heating is measured, for example, as follows. That is, after confirming the initial weight of the epoxy resin composition tablet, the tablet is put in an atmosphere at 105 ° C. for 2 hours, and the weight of the tablet is measured. Then, as shown in the following equation, a value obtained by dividing the reduced weight by the initial weight is a heating loss value (% by weight).

[0039]

(Equation 1)

The formation of a semiconductor device by encapsulating a semiconductor element with a resin using an epoxy resin composition having the above characteristics is performed by a transfer molding method.

The molding conditions for the transfer molding include, for example, curing conditions at a temperature of 170 to 180 ° C. for 1 to 3 minutes. Further, as a post-curing (after-curing) step, a condition of a temperature of 170 to 180 ° C. for 6 to 300 minutes can be given.

In the present invention, the cured epoxy resin composition, which is the resin-sealed portion of the semiconductor device sealed with the resin as described above, must have the following properties (A) and (B). No. (A) The high-temperature flexural modulus at 175 ° C. immediately after transfer molding of the cured epoxy resin composition is 250 kg / mm ² or less. (B) The glass transition temperature of the cured epoxy resin composition immediately after transfer molding is in the range of 125 to 150 ° C.

In the above characteristic (A), the high-temperature flexural modulus at 175 ° C. immediately after transfer molding is particularly preferably 100 to 250 kg / mm ² . That is,
If the high-temperature flexural modulus at 175 ° C. immediately after transfer molding exceeds 250 kg / mm ² , runner breakage occurs.

The high-temperature flexural modulus in the characteristic (A) is measured, for example, as follows. That is,
A measurement sample molded under molding conditions of 175 ° C. × 70 seconds was measured at 175 ° C. for 5 minutes in accordance with JIS-K-6911.
After standing for minutes, an autograph device (SHIMADZU
AG-500C).

In the above characteristic (B), particularly preferably, the glass transition temperature immediately after transfer molding is 13
The range is from 0 to 140 ° C. That is, if the glass transition temperature immediately after transfer molding is lower than 125 ° C., the high-temperature elastic modulus is too low, and insufficient curing occurs, and if it exceeds 150 ° C., the high-temperature elasticity is too high, resulting in brittleness.

The glass transition temperature in the above characteristic (B) is measured as follows. That is, 175 ° C
A measurement sample molded under molding conditions of × 70 seconds was heated at a rate of 5 ° C./min using a thermal mechanical analysis (TMA: MJ810EW2 manufactured by Rigaku Corporation).
It can be measured by creating a thermal expansion curve under the conditions described above and determining the transition point of the thermal expansion curve.

Next, examples will be described together with comparative examples.

First, prior to the examples, the following compounds were prepared.

[Epoxy resin A] o-cresol novolak type epoxy resin (epoxy equivalent 195, softening point 70
℃)

[Epoxy resin B] Brominated epoxy resin (epoxy equivalent 455, softening point 80 ° C)

[Phenol resin] Phenol novolak resin (hydroxyl equivalent 105, softening point 83 ° C)

[Curing accelerator] Triphenylphosphine

[Silica powder] Crushed fused silica powder (average particle size: 12 μm)

[Silane coupling agent] γ-glycidoxypropyltrimethoxysilane

[Release Agent] Carnauba Wax

[Flame retardant aid] Antimony trioxide

[Carbon black]

[0058]

Examples 1 to 6 and Comparative Examples 1 to 5 The components shown in the following Tables 1 and 2 were mixed in the proportions shown in the table, kneaded with a mixing roll machine heated at 90 ° C. for 5 minutes and cooled. By pulverizing, a desired powdery epoxy resin composition was obtained. The loss on heating of each of the epoxy resin compositions was measured according to the method described above. The values are shown in Tables 1 and 2 below.

[0059]

[Table 1]

[0060]

[Table 2]

Using the obtained epoxy resin compositions for semiconductor encapsulation of each of the examples and comparative examples, the characteristics were evaluated according to the following methods. The results are shown in Tables 3 and 4 below.

[Spiral Flow Value] EMMI 1-6 at 175 ± 5 ° C. using a spiral flow measuring mold.
The spiral flow value was measured according to 6.

[175 ° C. as indicated by flow tester viscosity
2 g of each of the above epoxy resin compositions was precisely weighed and molded into tablets. Then, this was put into a pot of a height type flow tester (CFT-100, manufactured by Shimadzu Corporation), and the load was measured with a load of 10 kg. The melted epoxy resin composition is placed in a die hole (diameter 1.0 mm x 1).
0 mm), the melt viscosity of the sample was determined from the moving speed of the piston when extruded.

[175 ° C. High Temperature Flexural Modulus] Each epoxy resin composition was measured according to the method described above.

[Glass Transition Temperature] The glass transition temperature was measured according to the method described above using each of the above epoxy resin compositions.

[Evaluation of Breakage of Runner] A semiconductor device [160-pin four-way flat package: QFP160] using a transfer molding machine using each of the above epoxy resin compositions.
pin (28 mm × 28 mm × thickness 3.0 mm), semiconductor device: 10 mm × 10 mm × thickness 370 μm] were produced. As a result, one in which no runner break occurred during one shot was evaluated as ○, one in which runner break was confirmed in some, and a cross in which runner break was confirmed in all. The transfer molding conditions were 175 ° C. × 70 seconds.

The presence or absence of voids in the above semiconductor device was confirmed using an ultrasonic microscope (manufacturer: Sonoscan, model: D-6000) or a soft X-ray device. Then, those in which voids were not confirmed were indicated by ○, and those in which voids were confirmed were indicated by x.

[0068]

[Table 3]

[0069]

[Table 4]

From the results shown in Tables 3 and 4, in the semiconductor device sealed with the cured epoxy resin composition satisfying the above characteristics (A) and (B), no runner break occurs at the time of transfer molding. Was. On the other hand, in the semiconductor device sealed with the epoxy resin composition cured product deviating from the characteristics (A) and (B), at least a part of the runner break occurs during the transfer molding for the products of Comparative Examples 1 to 4. did. In Comparative Example 5, voids were confirmed. In particular, the epoxy resin composition used in the above examples has a heating loss of 0.1.
The content was in the range of 5 to 0.30% by weight, and the cured product satisfied the above properties (A) and (B). On the other hand, the epoxy resin composition used in the comparative example has a loss on heating outside the range of 0.15 to 0.30% by weight, and the cured product has the above-mentioned properties (A) and (B).
At least one of them was off.

[0071]

As described above, the present invention is a semiconductor device in which a cured epoxy resin composition as a sealing resin immediately after transfer molding has the above characteristics (A) and (B). For this reason, in the semiconductor device, runner breakage does not occur when the mold is opened immediately after the transfer molding, and the semiconductor device can be taken out of the transfer molding die as a whole, and as a result, the subsequent workability is improved. .

When the cured epoxy resin composition is formed of an epoxy resin composition containing a cresol novolak type epoxy resin as a main component and a phenol novolak resin as a curing agent, excellent curability is obtained. Productivity is improved.

When the epoxy resin composition having a heat loss in the above specified range is produced as the epoxy resin composition before being subjected to the transfer molding, the above-mentioned properties (A) and (B) of the cured epoxy resin composition formed are obtained. In particular, it is easy to control the high-temperature flexural modulus, which is the characteristic (A), and as a result, a favorable semiconductor device having the above characteristics (A) and (B) can be easily obtained.

Claims (3)

[Claims] 1. A semiconductor device in which a semiconductor element is sealed with a sealing resin made of a cured epoxy resin composition by transfer molding, wherein the cured epoxy resin composition has the following properties (A) and ( B) A semiconductor device comprising: (A) The high-temperature flexural modulus at 175 ° C. immediately after transfer molding of the cured epoxy resin composition is 250 kg /
mm ² or less. (B) The glass transition temperature of the cured epoxy resin composition immediately after transfer molding is in the range of 125 to 150 ° C. 2. The semiconductor according to claim 1, wherein the cured epoxy resin composition is formed of an epoxy resin composition containing a cresol novolak type epoxy resin as a main component and a phenol novolak resin as a curing agent. apparatus. 3. A method of manufacturing a semiconductor device by sealing a semiconductor element with a resin by a transfer molding method using an epoxy resin composition, wherein the epoxy resin composition has a reduced heat loss before being subjected to the transfer molding method. 0.15-
A method for producing a semiconductor device, comprising 0.30% by weight and a cured product immediately after transfer molding having the following properties (A) and (B). (A) The high-temperature flexural modulus at 175 ° C. immediately after transfer molding of the cured epoxy resin composition is 250 kg /
mm ² or less. (B) The glass transition temperature of the cured epoxy resin composition immediately after transfer molding is in the range of 125 to 150 ° C.