JP3014900B2 - Semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin semiconductor device.

[0002]

2. Description of the Related Art In a conventional semiconductor device, the thickness of a package is generally 2 mm or more, and the thickness of each sealing resin layer on a semiconductor element and below a die pad is sufficiently large. Setting of the filling resin composition for filling when using such a molding die was easy. However, with the trend of miniaturization and thinning of the semiconductor package, the thickness of the package itself is 1 m.
m or less, and the thickness of the sealing resin layer below the die pad from the top of the semiconductor element in such a package may be set to 100 μm or less.

[0003]

At the time of manufacturing such a package, the setting of the resin composition that can be filled in the molding die is greatly affected by the viscosity as compared with the conventional thick package. Moreover, since the resin composition generally contains an inorganic filler having a particle size of 50 to 100 μm, clogging or the like may occur during the filling, and the filling of the resin composition may be insufficient. . For this reason, when the above-mentioned thin package is formed using a conventional resin composition, an unfilled portion or a through void (void) is generated. As described above, the sealing resin composition conventionally used cannot cope with the recent thinning of semiconductor devices, that is, the sealing resin having a package thickness of 1 mm or less and the upper part of the semiconductor element and the lower part of the die pad. In fact, it is difficult to mold a semiconductor device in which the thickness of the layer is set to 100 μm or less.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a thin semiconductor device having no unfilled portion or a through void in a sealing resin layer.

[0005]

In order to achieve the above object, a semiconductor device according to the present invention is a semiconductor device in which a semiconductor element is resin-sealed with an epoxy resin composition containing an inorganic filler. When the thickness of the thinnest portion of the sealing resin layer is set to x μm (x = 30 to 100), the inorganic filler satisfies the following (A). (A) The content of the inorganic filler having a particle diameter of 0.9 × μm or more is set to 2% by weight or less of the entire inorganic filler.

[0006]

In other words, the present inventors have conducted a series of studies to obtain a sealing resin composition in which an unfilled portion and a through void are not formed when a thin semiconductor device is formed.
As a result, as an essential component of the encapsulating resin composition, when the thickness of the thinnest portion of the encapsulating resin layer is set to x μm, an inorganic filler having a particle size substantially equal to or greater than the thickness is used. When an inorganic filler containing a small amount is used, the resin composition can be uniformly filled without the inorganic filler having a small particle diameter clogging the thinnest portion. For this reason, an unfilled portion or a through void is not formed in the obtained package. In addition, since the inorganic filler having a large particle size is distributed on the side portion of the package, it has been found that the growth of cracks generated inside the package is hindered, and the growth of cracks can be prevented. did.

Next, the present invention will be described in detail.

The epoxy resin composition used in the present invention comprises an epoxy resin (a component), a curing agent (b component),
It is obtained by using a special inorganic filler (component (c)) and is usually in the form of a powder or a tablet obtained by compressing it.

As the epoxy resin (a component), 2
If it has at least two epoxy groups, the molecular weight,
The molecular structure and the like are not limited, and conventionally known ones are used. For example, various epoxy resins such as bisphenol A type, bisphenol type, cresol novolak type, phenol novolak type, those having a naphthalene skeleton, and those having an alicyclic skeleton can be used. Among these epoxy resins, those having a melting point exceeding room temperature and exhibiting a solid or high-viscosity liquid at room temperature are preferably used. Further, in order to further contain the inorganic filler (component c), the epoxy resin (component a) preferably has a low viscosity.
C. I. The viscosity at 150 ° C. measured by a cone and plate viscometer is preferably 5 poise or less, more preferably 2 poise or less. A typical example satisfying the above low viscosity is 4,4'-dihydroxytetramethylbiphenyl glycidyl ether.

The curing agent (component (b)) functions as a curing agent for the epoxy resin (component (a)), and a conventionally known curing agent is used. Preferably, it has a hydroxyl group. For example, a phenol novolak resin is used. Specifically, it is preferable to use one having a repeating unit represented by the following formula.

[0011]

Embedded image

The epoxy resin (a component) and the curing agent (b)
For example, if the curing agent (component (b)) has a hydroxyl group, the compounding ratio of the (component) may be 0.5 to 2.0 equivalents per equivalent of epoxy group in the epoxy resin. preferable. More preferably 0.8-1.
Two equivalents.

In the above-mentioned special inorganic filler (component c),
The material is not particularly limited, and examples thereof include commonly used silica powder, alumina powder, quartz glass powder and the like. When silica powder is used, its content is preferably set to 50% by weight (hereinafter abbreviated as “%”) or more of the entire epoxy resin composition, more preferably 7%.
0% or more, particularly preferably in the range of 75 to 90%.
Moreover, it is more preferable to use spherical particles as the shape of the inorganic filler. The average particle diameter of the entire inorganic filler is preferably set to 5 to 25 μm. further,
It is necessary to satisfy the following (A). Particularly preferably,
The content of the inorganic filler having a particle diameter of 0.9 x μm or more is set within the range of 1 to 2% of the entire inorganic filler. The upper limit of the particle diameter is usually 0.99 × μm. That is, when the content of the inorganic filler having a particle size of 0.9xμm or more exceeds 2%, the inorganic filler having a large particle size of 0.9xμm or more is distributed in the thinnest layer portion, and This is because unfilled portions and through voids are formed during sealing. In the following (A), x is the thickness of the thinnest sealing resin layer portion of the semiconductor device, and x = 30 to 10
0 μm.

(A) The content of the inorganic filler having a particle size of 0.9 × μm or more is set to 2% or less of the entire inorganic filler.

The particle size of the inorganic filler is 0.9 × μ.
The measurement of the content ratio of m or more is performed as follows. That is, a standard sieve according to the JIS standard (for example, No. 270 has a sieve of 53 μm, No. 325 has a sieve of 45 μm, and No. 400 has a sieve of 38 μm)
m) or, similarly, the above-mentioned inorganic filler is sieved in a dry or wet manner by using an arbitrary sieve corresponding to a particle diameter of 0.9 × μm, and the weight of the inorganic filler remaining on the sieve Is measured and evaluated. In addition,
In the case of the wet method, the dispersion is performed with a dispersion medium (eg, water, acetone, or the like) that does not react with the inorganic filler.

The particle size distribution of the entire inorganic filler (component (c)) is preferably set as shown below. For example, in a particle size distribution curve (accumulated distribution on the vertical axis and particle size on the horizontal axis) obtained by an arbitrary particle size distribution measuring method, the distribution of 0.9 × μm is 98%.
~ 99%, 0.5xμm is 90 ~ 98%, 0.2xμm
Is preferably 40 to 80%, and 0.05 x μm is preferably 10 to 40%.

The epoxy resin composition used in the present invention contains, in addition to the above components a to c, a curing accelerator, a coloring agent such as silicone oil or rubber compound, carbon black, a coupling agent such as a silane coupling agent, Other additives such as a flame retardant such as antimony and brominated epoxy resin can be blended as required.

The epoxy resin composition used in the present invention is obtained, for example, as follows. That is, the components a to c and other additives are appropriately blended. This compound is kneaded in a kneading machine such as a mixing roll machine in a heated state to obtain a semi-cured resin composition. Next, the target epoxy resin composition is obtained by a series of steps of cooling it to room temperature, pulverizing it by a known means, and tableting as necessary.

The encapsulation of the semiconductor device using such an epoxy resin composition is not particularly limited, and can be performed by a usual method, for example, a known molding method such as transfer molding.

At this time, the epoxy resin composition for encapsulation has a melt viscosity at a mold temperature (usually 150 to 180 ° C.) for melting and press-fitting into a molding mold within a range of 20 to 2000 poise. Preferably, the melt viscosity is 20 to 1000 when the mold temperature is, for example, 175 ° C.
It is preferable to set in the range of poise. Generally, when a large amount of the inorganic filler (component c) is contained, the viscosity of the epoxy resin composition increases. However, in the thin IC package to be sealed with the resin of the present invention, the short side of the semiconductor element or the die pad is reduced. Since it is about 1 to 4 cm, the minimum melt viscosity at the molding temperature is 2 to completely fill the thinnest portion of the epoxy resin composition containing the specific inorganic filler (component (c)).
There is no particular problem if it is less than 000 poise. The minimum melt viscosity is measured by a Koka type flow tester, and the nozzle diameter may be 1 mm and the nozzle length may be 1 cm.

The semiconductor device thus obtained has the following effects in the sealing resin layer. That is, a side portion (shaded area P) of the semiconductor device shown in FIG.
, An inorganic filler having a large particle size is distributed. For this reason, the growth (elongation) of the crack generated inside is prevented, and the crack is prevented from reaching the surface of the package 4. Further, an inorganic filler having a small particle size is distributed in a thin portion of the sealing resin layer in an upper portion of the semiconductor element 1 and a lower portion of the die pad 2. For this reason, the toughness is improved, and the occurrence of cracks is prevented. In the figure, 3 is a lead frame, and 6 is a bonding wire.

[0022]

As described above, according to the semiconductor device of the present invention, the semiconductor element has the thickness of the thinnest portion of the sealing resin layer of xμ.
When set to m, an inorganic filler having a particle size substantially equal to or greater than its thickness is contained in a very small amount, and most of the resin is an epoxy resin composition containing an inorganic filler having a small particle size as an essential component. It is sealed. For this reason, the inorganic filler having a small particle diameter is smaller than the thickness of the thinnest layer portion and is filled without clogging the thinnest portion. Therefore, the toughness of the thinnest portion is improved, and cracks are unlikely to occur. In addition, unfilled portions and through voids are not formed in the obtained package. Further, since the inorganic filler having a large particle size is distributed on a side portion of the package, for example, when a crack occurs inside the package, the growth of the crack is hindered, and the growth of the crack is prevented. As described above, the semiconductor device of the present invention is most suitable for a thin device having a package thickness of 1 mm or less, and is compatible with recent miniaturization and thinning.

Next, examples will be described together with comparative examples.

First, prior to the examples, several types of epoxy resin compositions containing inorganic fillers having different particle size distributions were prepared.

[Preparation of Epoxy Resin Composition] 20 parts of 4,4'-dihydroxytetramethylbiphenyl glycidyl ether and 1 part of phenol novolak resin
2 parts, 1.0 part of triphenylphosphine, and spherical silica particles having a particle size distribution shown in Tables 1 to 3 below were blended, and heated in a mixing roll machine (about 10 parts).
(0 ° C.) to obtain a semi-cured resin composition. Next, this was cooled to room temperature and then pulverized by a known means to obtain a powdery epoxy resin composition. The minimum melt viscosity of each epoxy resin composition at the molding temperature (175 ° C.) was measured and is shown in Tables 1 to 3 below. Further, the existence probability of silica particles having a particle diameter of 0.9 x μm or more of the entire silica particles was measured for the thinnest layer portion (thickness x μm) of the thickness of the sealing resin portion of the semiconductor package. 1 to Table 3 together.

[0026]

[Table 1]

[0027]

[Table 2]

[0028]

[Table 3]

[0029]

Examples 1 to 15 and Comparative Examples 1 to 17 Using the respective epoxy resin compositions thus obtained, a semiconductor element was resin-sealed by ordinary transfer molding (molding temperature: 175 ° C.). Then, as shown in FIG. 2, in the sealing resin layer 5, the thickness of the sealing resin layer below the die pad 2 is x.
A plurality of semiconductor devices (x = 35 μm, 53 μm, 71 μm, 100 μm) were manufactured (see FIG. 2). In the figure, 1 is a semiconductor element, and 3 is a lead frame. The size of the semiconductor device is 8 × 18 mm, and the size of the die pad 2 is 5.8 × 14.5 mm.

The filling condition of the thinnest layer (thickness x μm) of the sealing resin portion in the manufactured semiconductor device was visually judged and evaluated. Furthermore, this part was polished and observed with a scanning electron microscope, and the particle size distribution and the amount of silica particles as designed were completely filled with silica, and the unfilled part was formed with ×. The results are shown in Tables 4 to 8 below.

(1) The thickness x of the thinnest layer of the sealing resin portion is 3
In the case of 5 μm.

[0032]

[Table 4]

[0033]

[Table 5]

(2) The thickness x of the thinnest layer of the sealing resin portion is 5
In the case of 3 μm.

[0035]

[Table 6]

(3) The thickness x of the thinnest layer of the sealing resin portion is 7
In the case of 1 μm.

[0037]

[Table 7]

(4) The thickness x of the thinnest layer of the sealing resin portion is 1
In the case of 00 μm.

[0039]

[Table 8]

From the results of Tables 4 to 8 , it can be seen that the resin composition was completely filled in the thinnest layer portion (thickness x μm portion) without forming any unfilled portion in any of the products of Examples. . Moreover, the toughness of the thinnest layer portion of the example product was improved.

[Brief description of the drawings]

FIG. 1 is a perspective view showing one embodiment of a semiconductor device of the present invention.

FIG. 2 is a cross-sectional view illustrating a semiconductor device for evaluation used in Examples and Comparative Examples.

[Explanation of symbols]

 1 Semiconductor element

Continuation of front page (56) References JP-A-4-318019 (JP, A) JP-A-5-144984 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 23 / 29 H01L 23/31

Claims (6)

(57) [Claims] 1. A semiconductor device in which a semiconductor element is resin-sealed with an epoxy resin composition containing an inorganic filler, wherein the thickness of the thinnest portion of the sealing resin layer is x μm (x
= 30 to 100), wherein the inorganic filler satisfies the following (A). (A) The content of the inorganic filler having a particle diameter of 0.9 × μm or more is set to 2% by weight or less of the entire inorganic filler. 2. The semiconductor device according to claim 1, wherein the content of the inorganic filler having a particle diameter of 0.9 × μm or more is set in a range of 1 to 2% by weight of the entire inorganic filler. 3. The inorganic filler has an average particle size of 5 to 25 μm.
3. The semiconductor device according to claim 1, wherein m is set to m. 4. An epoxy resin composition for semiconductor encapsulation containing the following components (a) to (c), wherein the inorganic filler as the component (c) satisfies the following (A): Epoxy resin composition for semiconductor encapsulation. (A) Epoxy resin. (B) a curing agent. (C) an inorganic filler. (A) The content of the inorganic filler having a particle size of 0.9xμm or more is set to 2% by weight or less of the entire inorganic filler (where x is the amount of the sealing resin layer after resin sealing of the semiconductor element). The thickness of the thinnest part, x = 30 to 100). 5. The epoxy resin composition for semiconductor encapsulation according to claim 4, wherein the content of the inorganic filler having a particle size of 0.9 × μm or more is set in a range of 1 to 2% by weight of the entire inorganic filler. . 6. The inorganic filler has an average particle size of 5 to 25 μm.
The epoxy resin composition for semiconductor encapsulation according to claim 4 or 5, wherein m is set to m.