JP3422446B2 - Semiconductor device manufacturing method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device by mounting a semiconductor element on a mother board or a daughter board in a face-down structure.

[0002]

2. Description of the Related Art As a recent demand for improving the performance of semiconductor devices, a method of mounting a semiconductor element in a face-down structure on a motherboard on which wiring circuits are formed or on a daughter board (flip chip method, direct chip attach method) Etc.) is receiving attention. This is a conventionally used method, for example, in the method of mounting on a mother board or a daughter board in a form in which a semiconductor element is contacted on a lead frame with a gold wire and packaged, delay of information transmission by wiring, This is due to the problem that an information transmission error or the like due to crosstalk occurs.

[0003]

On the other hand, in the above flip chip system and direct chip attach system,
Since the semiconductor element and the board having different linear expansion coefficients are directly electrically connected to each other, the reliability of the connecting portion becomes a problem. As a countermeasure against this, a liquid resin material is injected into the gap between the semiconductor element and the board and cured to form a resin cured body, and the stress concentrated in the electrical connection is also dispersed in the resin cured body to improve connection reliability. Have been adopted. However, the liquid resin material needs to be stored at an ultralow temperature (−40 ° C.) and, in addition, it needs to be injected with a syringe for injection into the gap between the semiconductor element and the board. There are problems such as difficulty in controlling the amount. Further, in the above liquid resin material, when selecting an epoxy resin excellent in moisture resistance reliability and a phenol resin-based material which is a curing agent, it cannot be used unless a diluent is used. There is a problem that voids are generated in the voids that are the injection portions.

The present invention has been made in view of the above circumstances, and is a method of manufacturing a semiconductor device using an epoxy resin-based encapsulating material which is solid at room temperature and which is excellent in moisture resistance reliability and which facilitates resin encapsulation work. The purpose is to provide.

[0005]

In order to achieve the above object, a method of manufacturing a semiconductor device of the present invention is to heat an electrode portion of a semiconductor element by contacting a wiring electrode of a wiring circuit board with a solder. A semiconductor element is mounted on the substrate by the above method, and then the resin composition for encapsulation (A), which is solid at room temperature, is placed on the element mounting surface of the substrate and melted by heating to form a gap between the substrate and the semiconductor element. In addition, the resin composition for encapsulation in the molten state is filled and cured to seal the gap between the substrate and the semiconductor element with resin. (A) contains the following components (a) to (c),
The encapsulating resin composition in which the content ratio of the components is set in the range of 50 to 90% by weight based on the entire encapsulating resin composition. (A) Epoxy resin. (B) A novolac type phenolic resin. (C) A silica powder having a maximum particle size of 30 μm or less.

[0006]

That is, according to the present invention, a semiconductor element is directly mounted on a substrate via solder, and a resin composition for encapsulation (A), which is solid at room temperature, is heated and melted in a space between the substrate and the semiconductor element. Then, it is made to be in a molten state, and this is filled and cured to seal the gap between the substrate and the semiconductor element with a resin. As described above, since the encapsulating resin composition (A) that is solid at room temperature is heated and melted to fill the gap between the substrate and the semiconductor element by utilizing the capillary phenomenon, the filling operation is easy, and the solid It is easy to store the resin material because it is used. Moreover, by using the silica powder of the encapsulating resin composition (A) with the maximum particle size set to 30 μm or less, the voids and the like can be favorably filled without filling voids.
In such a manufacturing method, it is particularly preferable to use, as the epoxy resin in the encapsulating resin composition (A), a biphenyl type epoxy resin or the like having the specific structure because the viscosity in the molten state is low. It is preferable because it facilitates filling by capillary action.

Next, the present invention will be described in detail.

The encapsulating resin composition (A) used in the semiconductor device manufacturing method of the present invention is an epoxy resin (a component).
And a novolac-type phenol resin (component b) and a specific silica powder (component c),
It is solid at room temperature and is used as pellets formed into various shapes by compressing powder. In addition, the said normal temperature specifically means the range of 20-50 degreeC.

The epoxy resin (component a) is not particularly limited as long as it is solid at room temperature, and conventionally known ones are used, and further, those having a low melt viscosity are preferably used. Particularly preferred is an epoxy resin having a structure represented by the following general formula (1), formula (2) or formula (3), from the viewpoint of low melt viscosity. These may be used alone or in combination of two or more.

[0010]

[Chemical 4]

[0011]

[Chemical 5]

[0012]

[Chemical 6]

In the epoxy resin having the structure represented by the above formulas (1) to (3), the epoxy equivalent of 150 to 230 is particularly preferable.
It is preferable to use one having a melting point of 60 to 160 ° C. in g / eq.

The novolac type phenolic resin (component b) used together with the epoxy resin (component a) is not particularly limited, and a commonly used one is used, and it is particularly preferable to use one having a low viscosity. Among them, the hydroxyl equivalent is 80 to 120 g / eq and the softening point is 8
It is preferable to use one having a temperature of 0 ° C. or lower. More preferably, the hydroxyl equivalent is 90 to 110 g / eq and the softening point is 50 to
It is 70 ° C. Particularly preferably, the hydroxyl equivalent is 100 to 11.
It has a softening point of 55 to 65 ° C. at 0 g / eq.

The mixing ratio of the epoxy resin (a component) and the novolac type phenol resin (b component) is such that the hydroxyl group equivalent in the novolac type phenol resin is 0.5 to 1 to 1 equivalent of the epoxy group in the epoxy resin. It is preferable to set it in the range of 6. More preferably, it is set in the range of 0.8 to 1.2.

The specific silica powder (component c) used together with the components a and b may be fused silica powder or crushed silica powder, and spherical silica is particularly preferably used. The silica powder (component c) having an average particle size of 0.1 to 25 μm is preferably used, and particularly preferably 0.5 to 2
It is 0 μm. Furthermore, it is necessary to use a material having a maximum particle size of 30 μm or less. Particularly preferably, the maximum particle size is 1-2.
It is 5 μm. That is, if the maximum particle size exceeds 30 μm, it may not be possible to fill the space between the substrate and the semiconductor element [voids sealed with the resin composition for sealing (A)]. From this point of view, the maximum particle size of the silica powder (component (c)) is 1 of the distance between the substrate and the semiconductor element [void sealed with the resin composition for sealing (A)]. It is preferably set to / 2 or less. It is more preferably 1/10 to 1/3. That is, by setting the maximum particle size to ½ or less, it is possible to satisfactorily fill the molten resin composition for encapsulation (A) between the substrate and the semiconductor element without causing voids or the like. Because.

The content of the above specific silica powder (component (c)) is 50 to 90% by weight of the whole encapsulating resin composition (A).
It is necessary to set it in the range (hereinafter abbreviated as “%”). Particularly preferably, it is 55 to 75%. That is, when the content of the silica powder (component c) is less than 50%, the characteristics of the cured resin for encapsulation, particularly the linear expansion coefficient, becomes large.
The difference between the semiconductor element and the above coefficient becomes large, causing defects such as cracks in the resin cured product or the semiconductor element. On the other hand, if it exceeds 90%, the melt viscosity of the encapsulating resin becomes high and the filling property becomes poor.

In the encapsulating resin composition (A) used in the present invention, a low stress such as a silicone compound (a side chain ethyleneglycol type dimethylsiloxane, etc.) may be added, if necessary, in addition to the components a to c. An agent, a flame retardant, a wax such as polyethylene or carnauba, a coupling agent such as a silane coupling agent (γ-glycidoxypropyltrimethoxysilane), or the like may be appropriately mixed.

Examples of the flame retardant include a brominated epoxy resin and the like, and a flame retardant aid such as diantimony trioxide is used.

The encapsulating resin composition (A) used in the present invention is obtained, for example, as follows. That is, the a-component and the b-component are mixed and melted, and the above-mentioned c-component and, if necessary, other additives are mixed and mixed. After that, a catalyst for reactivity adjustment is added to make a uniform system, which is then received on a pallet, cooled, crushed, tableted into a desired shape and pelletized.

The catalyst compounded for adjusting the reactivity is not particularly limited, and examples thereof include those conventionally used as a curing accelerator. Examples thereof include triphenylphosphine, tetraphenylphosphate, tetraphenylborate, 2-methylimidazole and the like.

The method of mixing the above components and the method of producing pellets is not limited to the above method. For example, a biaxial roll or a triaxial roll can be used in the mixing. Further, as a method for producing the pellets, a casting method, a sheet-like post-punching method, or the like can be used.

The shape of the pellets is not particularly limited, and it may be a cube, a cylinder, or the like as shown in FIG.
The wedge-shaped (substantially L-shaped) pellets 1 and the like are appropriately set according to the purpose, the size and shape of the substrate and the semiconductor element, and the like. Particularly preferable is the wedge-shaped pellet 1 shown in FIG. 1, which can be easily placed and positioned on the substrate and can be easily filled by utilizing the capillary phenomenon by heating and melting.

In the present invention, for example, a semiconductor device is manufactured as follows. That is, as shown in FIG. 2, the wiring electrode 3 on the substrate 2 having the wiring circuit formed on one surface thereof.
, Electrodes (bumps) made of metal (gold, nickel-gold alloy, etc.) formed on the lower surface of the semiconductor element 5 via the solder 4.
Abut 7. Then, the solder 4 is melted by heating and melting, and the semiconductor element 5 and the substrate 2 are joined.
Then, as shown in FIG. 3, a wedge-shaped pellet 1 is formed on the device mounting surface of the substrate 2 on which the semiconductor device 5 is mounted.
Is placed so that its central recessed portion (right-angled portion) is aligned with the edge portion of the semiconductor element 5. Then, the whole is heated to melt the pellet 1 to be in a molten state, and the capillary state is used to fill the void between the semiconductor element 5 and the substrate 2 with the molten sealing resin composition (A). Then, the voids are resin-sealed by curing. In this way, a semiconductor device as shown in FIG. 4 is manufactured. In FIG. 4, 6 is a sealing resin layer formed by sealing with the sealing resin composition (A).

The above-mentioned encapsulating resin composition (A) which is solid at room temperature
It is preferable to set the heating temperature in the molten state in the range of 70 to 250 ° C. in consideration of deterioration of the semiconductor element 5 and the substrate 2. And as a heating method,
Examples include infrared reflow ovens, dryers, warm air blowers, hot plates, and the like.

In the semiconductor device manufactured as described above, the size of the semiconductor element 5 is usually 5 to 20 m in width.
It is set to m × length 5 to 20 mm × thickness 0.1 to 0.6 mm. More suitable is width 8-18 mm x length 8-18
mm × thickness 0.2 to 0.5 mm. The size of the substrate 2 on which the wiring circuit mounting the semiconductor element 5 is formed is usually set to a width of 10 to 70 mm × a length of 10 to 70 mm × a thickness of 0.05 to 3.0 mm. More preferable is width 15 to 50 mm x length 15 to 50 mm x thickness 0.1.
It is 2.0 mm. The distance between the semiconductor element 5 and the void of the substrate 2 filled with the sealing resin composition (A) is usually 5 to 100 μm. Particularly, considering the characteristics of the encapsulating resin composition (A) used in the present invention, the distance between the both is preferably set to 10 to 70 μm.

The encapsulating resin layer 6 formed by encapsulating with the encapsulating resin composition (A), that is, the encapsulating resin composition (A), is used at various operating temperatures. Melt viscosity of 3 to 200 poise, gel time of 150 ℃
In 0.5 to 30 minutes, the cured product preferably has a linear expansion coefficient of 7 to 40 ppm. More preferably, the melt viscosity is 10 to 100 poise, the gel time is 150 ° C. for 0.5 to 20 minutes, and the linear expansion coefficient is 12 to 35 ppm. Particularly preferably, the melt viscosity is 1
0 to 70 poise, gel time at 150 ° C. for 0.5 to 15 minutes, and coefficient of linear expansion of 13 to 30 ppm. That is, when the melt viscosity is set within the above range, the filling property becomes good. Further, by setting the gel time within the above range, it becomes possible to shorten the molding workability, especially the curing time. Further, by setting the linear expansion coefficient within the above range, it becomes possible to prevent defects due to stress such as cracks in the resin cured product or the semiconductor element. The melt viscosity was measured by a flow tester viscometer, and the gel time was measured on a hot plate. The linear expansion coefficient was measured by thermomechanical analysis (TMA).

[0028]

As described above, according to the method of manufacturing the semiconductor device of the present invention, the semiconductor element is directly mounted on the substrate through the solder, and the gap between the substrate and the semiconductor element is solid and sealed at room temperature. The resin composition (A) is melted by heating to be in a molten state, filled and cured to seal the gap between the substrate and the semiconductor element with a resin. As described above, since the encapsulating resin composition (A) that is solid at room temperature is heated and melted to fill the gap between the substrate and the semiconductor element by utilizing the capillary phenomenon, the filling operation is easy, and the solid It is easy to store it because it is used. In particular, the particle size of the silica powder (component c) in the encapsulating resin composition (A) is 1 / the distance between the substrate and the semiconductor element.
By using No. 2, the filling of the gap between the substrate and the semiconductor element can be satisfactorily performed without causing voids.
Then, as the epoxy resin (a component) constituting such a resin composition for encapsulation (A), especially the above-mentioned general formula (1)
It is particularly preferable to use an epoxy resin having a structure represented by any one of (3)-(3) because the viscosity in the molten state is low and the filling by capillarity is facilitated.

Next, examples will be described together with comparative examples.

First, each component shown below was prepared prior to the examples.

[Epoxy resin a1] A biphenyl type epoxy resin having a structure represented by the following formula (4).

[0032]

[Chemical 7]

[Epoxy resin a2] An epoxy resin having a structure represented by the following formula (5).

[0034]

[Chemical 8]

[Epoxy Resin a3] A biphenyl type epoxy resin having a structure represented by the following formula (6).

[0036]

[Chemical 9]

[Epoxy resin a4] A liquid bisphenol type epoxy resin (epoxy equivalent: 190 g / eq).

[Curing agent b1] A novolac type phenol resin (hydroxyl group equivalent: 104 g / eq, softening point 59 ° C.).

[Curing agent b2] Liquid methylated hexahydrophthalic acid.

[Curing agent b3] Liquid allylated phenol.

[Silica powders c1 to c6] Spherical silica powders shown in Table 1 below.

[0042]

[Table 1]

[Catalyst d1] Triphenylphosphine.

[Catalyst d2] Mixture of tetraphenyl phosphate and tetraphenyl borate (molar mixing ratio 1
/ 1).

[Catalyst d3] 2-methylimidazole.

[Flame Retardant] Brominated epoxyphenol novolac.

[Flame retardant aid] Antimony trioxide.

[Wax] Polyethylene.

[Silicone Compound] A side chain ethylene glycol type dimethyl siloxane.

[Coupling Agent] γ-glycidoxypropyltrimethoxysilane.

[0051]

Examples 1-27, Comparative Examples 1-9 Using the above components,
The components were mixed in the proportions shown in Tables 2 to 5 below. This was received on a pallet, cooled, crushed and tableted into a wedge shape to prepare a wedge-shaped pellet 1 shown in FIG.

[0052]

[Table 2]

[0053]

[Table 3]

[0054]

[Table 4]

[0055]

[Table 5]

Using the wedge-shaped pellets of the respective Examples and Comparative Examples thus obtained, a sample product resembling a semiconductor device for confirming the filling effect was manufactured as follows. First of all, each size (5
X5 mm, 10 x 10 mm) silicon chips were prepared. Then, as shown in FIGS. 5A and 5B, the glass plate 11 is inserted through the spacer 10 having a thickness of 50 μm.
The silicon chip 12 was bonded and mounted on (40 × 40 mm). Then, as shown in FIG. 6, the wedge-shaped pellets 13 are formed into silicon chips 12 whose concave portions (corners).
It was placed so as to match the edge part of. Next, the pellets 13 are melted by passing them through an infrared reflow furnace having a temperature of 150 ° C., and the silicon chips 12 and the glass plate 11 are melted.
By filling and curing the space between them by utilizing the capillary phenomenon, the inside of the space was resin-sealed. As a result of the sealing as described above, it was visually evaluated whether or not the molten resin composition was completely filled in the voids. As a result, those that were completely filled were represented by ◯, and those that were not completely filled with voids and the like were represented by x, and the results are shown in Tables 6 to 10 below.

Next, transfer molding (molding condition: 150) was carried out using the pellets of each of the above Examples and Comparative Examples.
℃ × 20 minutes + post-curing 175 ℃ × 300 minutes),
A moisture resistant reliability evaluation package in the form of a dual in-line package (DIP) was produced. Then, using this evaluation package, a device corrosion test (PCBT test) is performed at a bias of 130 ° C. × 85% × 30 V, and a mean failure time (MTTF) is measured to evaluate the moisture resistance reliability of the sealing resin. did. The results are also shown in Tables 6 to 10 below.

Further, the pellets of each of the above Examples and Comparative Examples were heated and melted and cured (condition: 150 ° C. × 20 minutes + 17).
The linear expansion coefficient was measured by thermomechanical analysis (TMA). Further, each melt viscosity and gel time were measured according to the method described above. The results are also shown in Tables 6 to 10 below.

[0059]

[Table 6]

[0060]

[Table 7]

[0061]

[Table 8]

[0062]

[Table 9]

[0063]

[Table 10]

From the results shown in Tables 6 to 10, it can be seen that in all of the examples, the filling was performed well, and the average failure time was long even in the PCB test and the reliability was excellent. On the other hand, in Comparative Examples 1 to 4 and 9, the filling property was good, but the average failure time by the PCBT test was very short and the reliability was poor. In Comparative Examples 5 to 6 and 8, the average failure time by the PCBT test exceeded 200 hours and was not bad as an evaluation, but the filling property was poor. Further, in Comparative Example 7, the filling property and the result of the PCBT test were good, but the linear expansion coefficient was large, and there was a defect that a crack was generated in the resin portion after molding.

[Brief description of drawings]

FIG. 1 is a perspective view showing a pellet for sealing used in a method for manufacturing a semiconductor device of the present invention.

FIG. 2 is a cross-sectional view showing a state in which a semiconductor element and a substrate are bonded together.

FIG. 3 is an explanatory view showing an example of a method for manufacturing a semiconductor device of the present invention.

FIG. 4 is a cross-sectional view showing a semiconductor device obtained by the method for manufacturing a semiconductor device of the present invention.

5A is a cross-sectional view showing a sample product for confirming a filling effect, and FIG. 5B is a plan view thereof.

FIG. 6 is an explanatory diagram showing a process of manufacturing a sample product for checking a filling effect.

[Explanation of symbols]

1 wedge-shaped pellets 2 substrates 3 wiring electrodes 4 solder 5 Semiconductor element 6 Sealing resin layer

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Takashi Fukushima 1-2 1-2 Shimohozumi, Ibaraki City, Osaka Prefecture Nitto Denko Corporation (72) Shinichiro Suto 1-2 1-2 Shimohozumi, Ibaraki City, Osaka Prefecture No. Nitto Denko Co., Ltd. (72) Inventor Tatsushi Ito 1-2, Shimohozumi, Ibaraki City, Osaka Prefecture Nitto Denko Co., Ltd. (56) Reference JP-A-51-102466 (JP, A) JP 57-148360 (JP, A) JP-A 2-96343 (JP, A) JP-A 5-315396 (JP, A) JP-A 8-31870 (JP, A) (58) Fields investigated (Int .Cl. ⁷ , DB name) H01L 21/56 H01L 21/60

Claims (4)

(57) [Claims] 1. A semiconductor element is mounted on a substrate by heating an electrode portion of the semiconductor element by abutting on the wiring electrode of the wired circuit board via solder, and then the resin composition for encapsulation which is solid at room temperature. By placing (A) on the element mounting surface of the substrate and heating and melting, the gap between the substrate and the semiconductor element is filled and cured with the resin composition for sealing in the molten state to form the substrate. A method of manufacturing a semiconductor device, characterized in that a gap between the semiconductor element and the semiconductor element is sealed with resin. (A) contains the following components (a) to (c),
The encapsulating resin composition in which the content ratio of the components is set in the range of 50 to 90% by weight based on the entire encapsulating resin composition. (A) Epoxy resin. (B) A novolac type phenolic resin. (C) A silica powder having a maximum particle size of 30 μm or less. 2. The method for manufacturing a semiconductor device according to claim 1, wherein the maximum particle size of the silica powder as the component (c) is ½ or less of the distance between the substrate and the semiconductor element. 3. The epoxy resin as the component (a),
The method for manufacturing a semiconductor device according to claim 1, wherein the epoxy resin is at least one epoxy resin selected from the group consisting of epoxy resins represented by the following general formulas (1) to (3). [Chemical 1] [Chemical 2] [Chemical 3] 4. The method for manufacturing a semiconductor device according to claim 1, wherein the softening point of the novolac type phenolic resin which is the component (b) is 80 ° C. or lower.