JP2001217268A - Semiconductor device and it manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent drop in the reliability of a semiconductor device due to bias of a filler in a liquid resin in the semiconductor device in which a semiconductor element is bonded to a wiring board by using bump electrodes, and in which the gap between the semiconductor element and the writing board is filled with the liquid containing the filler so as to be hardened. SOLUTION: The semiconductor element 1 is bonded to the wiring board 3 by using bump electrodes 5. Liquid resin 9 is filled between the semiconductor element 1 and the wiring board so as to be hardened. In order to reduce the coefficient of thermal expansion of the resin after its hardening, a filler 7 such as silica filler or the like is filled into a resin composition 6. The specific gravity of the filler 7 which is mixed with the resin composition 6 is made to agree nearly with the specific gravity of the resin composition 6, and the filler which has a hollow structure at a space rate of 40 to 60% is used. As a result, the filler in the resin is dispended uniformly into the resin without being unbalanced, and the reliability of the semiconductor device is enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device and a method of manufacturing the same, and more particularly, to a method for mounting a semiconductor element on a wiring board through a bump electrode such as a solder bump, and then filling a gap between the semiconductor element and the wiring board with a resin. The present invention relates to a semiconductor device to be filled and a manufacturing method thereof.

[0002]

2. Description of the Related Art As information terminal equipment and the like have become smaller and more sophisticated, there has been a demand for smaller and faster semiconductor devices to be mounted thereon. A method of connecting a semiconductor element to a wiring board (hereinafter, simply referred to as a substrate) via a bump electrode such as a solder bump is excellent in electric characteristics and a mounting area is small because a connection distance between the semiconductor element and the substrate is short. Application to small information terminal devices and the like is progressing.

In order to extend the life of a connection portion such as a solder bump or to efficiently transfer heat from a semiconductor element to a substrate, this semiconductor device is made of a resin having an insulating property and / or a high thermal conductivity, or both. Is filled in the gap between the semiconductor element and the substrate. Therefore, it is more important to reliably and quickly fill the resin in terms of improving the reliability and manufacturing efficiency of the semiconductor device.

Conventionally, for filling the resin between the semiconductor element and the substrate, a liquid resin is used as disclosed in, for example, Japanese Patent Application Laid-Open No. 8-241900. And filling the space between the semiconductor element and the substrate with a resin by utilizing the capillary phenomenon.

FIG. 4 shows a conventional resin filling method for a semiconductor device. A semiconductor element 1 is connected to an electrode 4 on a substrate 3 and an electrode 2 on the semiconductor element by a protruding electrode 5 made of a solder bump or the like. Have been. The semiconductor element 1 and the substrate 3
The liquid filling resin 9 is filled using the syringe 8 between them.
After the filling of the resin is completed, the semiconductor device is kept at a high temperature in an oven or the like to cure the filling resin.

[0006]

In manufacturing the conventional semiconductor device shown in FIG. 4, a semiconductor element 1 and a substrate 3 are manufactured.
In order to reduce the thermal expansion coefficient of the resin 9 and to reduce the thermal stress generated at the connection portion between the semiconductor element 1 and the substrate 3, a filler made of silica powder is added to the resin 9 with respect to the resin component. About 70% by weight is blended.

During the curing process of the resin, there is a problem that the viscosity of the resin in the filler resin decreases, and the filler compounded tends to settle down due to the difference in specific gravity between the resin and the filler. When the resin is cured in such a state, the filler is present unevenly in the resin.

That is, when the compounding state of the filler in the resin becomes non-uniform, the filler is originally mixed with the resin to reduce the coefficient of thermal expansion so that the junction between the semiconductor element in the mounted state and the substrate on which the semiconductor element is mounted, etc. And the effect of improving the connection life and the like becomes insufficient, thereby significantly reducing the reliability of the semiconductor device. Therefore, it has been strongly desired to prevent the filler from settling during the curing process of the resin.

Therefore, an object of the present invention is to solve the above-mentioned conventional problems, and a first object of the present invention is to provide a semiconductor device in which a filler is uniformly dispersed in a cured resin. A second object is to provide a method of manufacturing a semiconductor device capable of shortening a resin filling time and improving workability.

[0010]

As a method of preventing the settling of the filler, there are a method of increasing the viscosity of the resin constituting the filling resin and a method of reducing the particle size of the filler to be mixed. However, when the viscosity of the resin in the filling resin is increased, the viscosity of the filling resin increases, and the time for filling the resin between the semiconductor element and the substrate on which the semiconductor element is mounted becomes longer, thereby significantly reducing the workability.

In general, even when the amount of the filler is constant and the particle diameter is reduced, the viscosity of the filling resin tends to increase, and the workability is significantly reduced as described above.

The inventors of the present invention have conducted various experiments and studies in order to achieve the above object, and have found that in order to prevent the settling of the filler in the filling resin without reducing the workability as described above. Has found that it is effective to minimize the difference between the density of the resin in the filling resin and the apparent density of the filler.

In order to reduce the apparent density of the filler, there is a method of changing the material of the filler to a material having a lower density.
In this case, the thermal expansion coefficient of the filling resin increases, and there is a possibility that the connection reliability in a temperature cycle test or the like of the semiconductor device sealed with this resin composition may be reduced.

Therefore, in order to prevent the sedimentation of the filler, since the influence on the thermal expansion coefficient of the resin composition is small, the above-mentioned problem can be solved by using a filler containing air bubbles in the filler resin. It became clear that.

The outline of a typical invention among the inventions disclosed by the present application will be briefly described as follows.

That is, the semiconductor device of the present invention is characterized in that a semiconductor element is mounted and connected on a wiring board via a protruding electrode, and a resin containing a filler is filled in a gap between the semiconductor element and the wiring board. A semiconductor device having a structure as described above, wherein the filler in the resin has a hollow structure substantially equal to the specific gravity of the resin, and is uniformly dispersed in the resin. The hollow structure means that the filler contains bubbles.

The specific gravity of the resin filled in this type of semiconductor device depends on the type of the resin, but is generally about 0.9 to 1.0. On the other hand, in the case of, for example, silica particles, which are a conventional typical filler, the specific gravity is 2.0 to 2.2, and there is almost no void (void ratio ≒ 0%).

However, the filler used in the present invention has a hollow structure almost equal to the specific gravity of the resin as described above.
Being substantially equal to the specific gravity of the resin means having a specific gravity of about 0.8 to 1.1.

Further, the method of manufacturing a semiconductor device according to the present invention is characterized in that a semiconductor element is mounted and connected on a wiring board via a protruding electrode, and the semiconductor element mounted and connected on the wiring board is connected to a semiconductor device. A method of manufacturing a semiconductor device, comprising: a step of injecting a liquid resin containing a filler into a gap between the wiring board and filling the gap with the resin; and a step of curing the filled liquid resin. In the step of injecting the filled liquid resin and filling the gap with the resin, a filler having a hollow structure almost equal to the specific gravity of the resin is blended into the resin as a filler, and uniformly dispersed and mixed to prepare a liquid resin. It has a process.

[0020]

Hereinafter, the present invention will be described more specifically with reference to the drawings. FIG. 1 is a schematic cross-sectional view of a semiconductor device according to an embodiment of the present invention. In the semiconductor device of the present invention, the electrode 2 provided on the semiconductor element 1 and the electrode 4 provided on the substrate 3 are electrically connected by a connection terminal 5 made of solder, gold, conductive resin, or the like. A liquid resin 9 in which a filler 7 is blended with a resin component 6 is injected and filled into the gaps between the substrates 3 by, for example, a syringe, and cured to form a resin filled layer in which the filler is uniformly dispersed in the resin. I have.

For the electrical connection, as described above, the connection terminal 5 may be a conductive resin containing a filler of gold, solder or silver, a spherical polymer surface coated with a conductive metal such as Ni, or the like. And a metal sphere such as copper.

The electrode 4 generally has a copper wiring surface plated with nickel / gold. Depending on the material of the connection terminal 5, tin plating or a method of coating the copper electrode with a flux may be used. Alternatively, a method of pre-coating solder may be applied.

The resin 9 filling the gap between the semiconductor element 1 and the substrate 3 includes, for example, silica (silicon dioxide) for reducing the coefficient of thermal expansion of the resin for the purpose of reducing the stress generated in the connection terminal portion. An inorganic filler 7 made of, for example, alumina, boron nitride, or the like is previously mixed, and the filler is uniformly dispersed in the resin filled between the semiconductor element 1 and the substrate 3.

The filler may be in the form of particles having any of a spherical shape and a square shape. However, a spherical shape is used in order not to decrease the fluidity of the resin even if the amount of the filler is increased. Is more desirable. In addition, the filler has a hollow structure that contains air bubbles and is almost equal to the specific gravity of the resin in order to disperse the filler uniformly in the resin and to prevent the resin component and the filler from separating during the semiconductor device manufacturing process. are doing.

When the proportion of the space in the filler (the porosity) is small, the effect of preventing the settling of the filler is insufficient if the proportion of the space is small, and if the proportion of the space is large, the proportion in the semiconductor device manufacturing process is low. Since the filler floats upward and the bias is generated in the filler, a porosity of approximately 40 to 60% is desirable.

The electrode 2 on the surface of the semiconductor element is connected to a circuit inside the semiconductor element, and the electrode 4 on the substrate 3 is connected to the inside of the substrate. As the resin component 6 that fills the gap between the semiconductor element 1 and the substrate 3, the above-mentioned filler 7 is blended. Generally, a thermosetting resin such as an epoxy resin, a phenol resin, and a polyimide resin, and furthermore, A mixture containing a thermoplastic component such as silicone, polyethylene terephthalate, or polybutadiene is used.

The preferred compounding ratio of the filler 7 to the resin component 6 is usually about 22 to 42% by weight.

For the preparation of the liquid resin 9, the resin component and the filler are mixed in the above mixing ratio, and these are sufficiently stirred by a well-known stirrer to disperse the filler well in the resin. A well-known dispersant may be added depending on the material or the amount of the filler to enhance the dispersibility, or the surface of the filler may be previously treated with a dispersant. Further, a flame retardant such as brominated epoxy or Sb ₂ O ₃ can be added to the resin.

[0029]

FIG. 2 and FIG. 2A schematically show a manufacturing process of the semiconductor device shown in FIG. In FIG. 2A,
A semiconductor element 1 having an electrode 2 on which a protruding electrode (solder) 5 serving as a connection terminal is formed is mounted on a substrate 3.
As shown in (b), the solder is melted by infrared reflow, vapor reflow, or the like, and connected to the electrode 4 of the substrate 3.

Thereafter, as shown in FIG. 2C, a liquid resin 9 prepared in advance by a syringe 8 is injected and filled into the gap between the semiconductor element 1 and the substrate 3. This filling may be performed at room temperature, or the filling of the resin may be performed by heating the substrate, the semiconductor element or the resin to an appropriate temperature in advance.

FIG. 2A (d) shows a state in which the gap between the semiconductor element 1 and the substrate 3 is completely filled with the liquid resin 9. Thereafter, as shown in FIG. 2A (e), the heater 11 is energized in the high-temperature bath 10 to heat and cure the resin. The specific gravity of fillers such as silica (silicon dioxide), alumina, boron nitride, etc., incorporated in the resin is almost the same as that of resins that do not contain them, and the resin hardens without causing settling or floating during the curing process. The reaction proceeds, and the final form, FIG. 2A (f), is obtained.

In FIG. 2, the gap between the semiconductor element 1 and the substrate 3 is horizontal when the resin is injected and filled.
It may be performed in a vertical state. If it takes a long time to inject and fill the resin, the filler moves during the resin filling process, which may cause a large unevenness in the amount of the filler present on the surface of the semiconductor element. Therefore, as shown in FIG. 3, if the semiconductor element and the substrate are set up and the gap is set vertically, and the resin is injected and filled,
The injection time is shortened, the unevenness of the movement of the filler is reduced, and the reliability is improved.

Further, according to the method of the present invention, as shown in FIG. 4, when semiconductor elements are mounted on both sides of a substrate and the space between the semiconductor element and the substrate is filled with resin, the resin is filled on both sides. It is possible to cure the resin from
Also in this case, the filler in the filler resin does not become uneven.

On the other hand, FIGS. 5 and 6 show a comparative example in which a liquid resin 9 containing a conventional filler 7 is injected into a gap between the semiconductor element 1 and the substrate 3 and cured. FIG. 5 shows a case where the resin 6 is cured such that the semiconductor element 1 is on the upper side, and the filler 7 in the resin is biased toward the lower substrate 3 during curing.

FIG. 6 shows a semiconductor device 1 on both surfaces of a substrate 3.
The resin is filled using a liquid resin 9 containing the same conventional filler 7 as in the case of FIG. 5, and then the resin is cured. The filler 7 is settled, and the filler 7 is biased toward the semiconductor element 1 in the filled resin portion below the substrate 3, and is biased toward the substrate 3 in the resin portion on the upper surface of the substrate 3.

Table 1 summarizes the results of a reliability evaluation of a temperature cycle test using various filling resins, in comparison with a comparative example (conventional example).

[0037]

[Table 1]

In each of the examples and comparative examples, the filling liquid resin 9 was prepared by mixing an imidazole-based resin with an equivalent amount of a bisphenol type epoxy resin (specific gravity 0.90 to 0.99) and an acid anhydride curing agent as the resin component 6. 1% by weight of a curing accelerator was blended, and spherical fused silica powder having an average particle diameter of 5 μm was further blended as a filler 7 to prepare the composition. The porosity and amount of the silica powder used in each of the examples and comparative examples are shown in the table.

As the substrate 3, a normal glass epoxy substrate is used. As the semiconductor element 1, a 10 mm square substrate having 400 pins arranged at a pitch of 500 μm is used.
For the connection, a tin-lead eutectic solder having a height of 300 μm was used as the connection terminal 5.

The resin was filled by the method shown in the process diagram of FIG. That is, a liquid resin 9 in which a filler 7 is previously blended is prepared in advance, and a syringe 8 is used at about 75 ° C.
The substrate 3 was placed on a hot plate heated to a temperature of 5 ° C., and was filled into the gap between the semiconductor element and the substrate.

In Examples 1 to 3, hollow fillers 7 having different void ratios were mixed in a liquid resin.
Example 1 had a porosity of 50% (specific gravity 1.0 to 1.1), and Example 2
Is 40% (specific gravity 1.1 to 1.2), and Example 3 is 60% (specific gravity 0.9).
~ 1.0). The curing of the resin was performed in a high-temperature bath 10 at 150 ° C. for 2 hours as shown in FIG. 2A (e).

In Comparative Examples 1 to 3, the resin was filled under the same conditions as in the above Examples except for the porosity and blending amount of the filler. In Comparative Example 1, the filler had no space (0% porosity / specific gravity). 2.
2), Comparative Example 2 was filled with a resin having a porosity of 20% (specific gravity 1.6 to 1.8), and Comparative Example 3 was filled with a resin having a porosity of 75% (specific gravity 0.6).

The semiconductor device after the resin curing is -55 ° C./10
Min, 125 ° C / 10 min temperature cycle test (500 cycles, 100
(0 cycles, 2000 cycles), and after each cycle test, the connection of the semiconductor element 1 and the substrate 3 was checked for conduction.

The results in Table 1 will be described.
In the comparative examples, the filling time was 45 seconds (s) regardless of the presence or absence of the porosity in the filler, and there was no difference due to the porosity. However, there was a large difference between the bias state of the filler in the resin and the temperature cycle test.

That is, in the case of the porosity of 40 to 60% in this embodiment, no bias (settling) of the filler was observed, and the temperature cycle test was 0 out of 10 (shown as 1/10 in the table). Very high reliability and good results were obtained. On the other hand, in the case of the comparative examples, a defective product having no conduction, which was 1/10 in the 2000-cycle test, occurred.

In each of the comparative examples, the dispersibility of the filler in the resin was inferior, and unevenness was observed. When the void ratio is 0% in Comparative Example 1, and when the void ratio is as small as 20% in Comparative Example 2, the filler settles down (on the substrate). Is higher than 75%
(Semiconductor element side) tend to float.

As is clear from Table 1, in the case of this embodiment,
It can be confirmed that the connection life is long, the bias of the filler is small, and the filler is uniformly and well dispersed in the resin.

The fact that the connection life is long means that the filler which is uniformly dispersed reduces the coefficient of thermal expansion to sufficiently reduce the stress generated at the junction between the semiconductor element in the mounted state and the substrate on which it is mounted. It has an effect that can be reduced.

Further, according to the production method of the present invention, since the filler is uniformly dispersed in the liquid resin, there is no need to worry about sedimentation unlike the prior art, so that the liquid resin is filled in the gap between the semiconductor element and the substrate. , And the yield of manufacturing highly reliable semiconductor devices is significantly improved.

[0050]

As described in detail above, according to the present invention, the intended object of uniformly dispersing the filler in the resin filling the gap between the semiconductor element and the substrate can be achieved. That is, the connection reliability of the semiconductor device in which the semiconductor element is mounted on the wiring board via the bump electrode such as a solder bump and then the gap between the semiconductor element and the wiring board is filled with the resin can be remarkably improved.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view illustrating an embodiment of the present invention.

FIG. 2 is a schematic view showing a manufacturing process of a semiconductor device according to one embodiment of the present invention.

FIG. 2A is a schematic view showing a manufacturing process of a semiconductor device according to one embodiment of the present invention;

FIG. 3 is a resin filling step diagram according to another embodiment of the present invention.

FIG. 4 is a schematic view of a resin filling process according to a conventional method.

FIG. 5 is a cross-sectional observation view of resin filling as a comparative example.

FIG. 6 is a cross-sectional observation view of resin filling as another comparative example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Semiconductor element, 2 ... Electrode on a semiconductor element, 3 ... Wiring board, 4 ... Electrode on a wiring board, 5 ... Connection terminal (projection electrode) 6 ... Resin, 7 ... Filler, 8 ... Syringe, 9 ... Liquid resin, 10… high temperature bath, 11… heater.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Yoshihide Yamaguchi, 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside the Research Institute of Production Technology, Hitachi, Ltd. (72) Shigeharu Tsunoda 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Address F-term in Hitachi, Ltd. Production Engineering Laboratory (reference) 5F044 LL01 RR17 5F061 AA01 BA03 CA04 CB02

Claims (6)

[Claims] 1. A semiconductor device having a structure in which a semiconductor element is mounted and connected on a wiring board via a protruding electrode, and a gap between the semiconductor element and the wiring board is filled with a resin containing a filler. A semiconductor device comprising a filler having a hollow structure substantially equal to the specific gravity of a resin and uniformly dispersed in the resin. 2. A semiconductor device having a structure in which a semiconductor element is mounted and connected on a wiring board via a protruding electrode, and a gap between the semiconductor element and the wiring board is filled with a resin containing a filler. A semiconductor device characterized in that the filler therein is made of a material having a hollow structure with a porosity of about 40 to 60% substantially equal to the specific gravity of the resin and uniformly dispersed in the resin. 3. A step of mounting and connecting a semiconductor element on a wiring board via a protruding electrode, and injecting a liquid resin containing a filler into a gap between the semiconductor element mounted and connected on the wiring board and the wiring board. Filling a gap with a resin, and a method of manufacturing a semiconductor device including a step of curing the resin, wherein in the step of injecting a liquid resin containing the filler and filling the gap with the resin, A method for manufacturing a semiconductor device, comprising a step of blending a filler having a hollow structure almost equal to the specific gravity of the resin into the resin as a filler, and uniformly dispersing and mixing to prepare a liquid resin. 4. The method according to claim 1, wherein the filler compounded in the liquid resin comprises a filler having a hollow structure having a porosity of 40 to 60%, and a step of uniformly dispersing and mixing the filler in the resin is provided. 4. The method for manufacturing a semiconductor device according to item 3. 5. The resin is composed of a thermosetting resin or a resin in which a thermoplastic resin component is blended, and the filler is composed of an inorganic filler. 5. The method for manufacturing a semiconductor device according to claim 3, wherein 22% to 42% is obtained. 6. The thermosetting resin is at least one of an epoxy resin, a phenol resin and a polyimide resin,
The thermoplastic resin is at least one of silicone, polyethylene terephthalate and polybutadiene,
The method of manufacturing a semiconductor device according to claim 3, wherein the filler is at least one inorganic filler of silica, alumina, and boron nitride.