JPH0382145A - Semiconductor device and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain a semiconductor device having good heat dissipation characteristics by a method wherein in the device to be constituted in a structure wherein one surface of a semiconductor element is fixed on the inner wall surface of a package through a bonding substance, a void dispersing matter is laid in the bonding matter between the element and the package. CONSTITUTION:The rear surface of a chip 7 is fixed on the inner wall surface of a cap 6 through a bonding matter 11. As this bonding matter 11, ones having good adhesion to the chip 7 and the cap 6 are chosen so as to discharge a role to transfer rapidly heat generated in the cap 7 to the cap 6 and at the same time, ones having a high heat conductivity are chosen. Moreover, a net matter 14 is provided in the bonding matter 11 (a solder). This net matter 14 discharges a role that in case there is such a fact as the air is caught up in the solder and voids are generated at the time of assembly of a semiconductor device, these voids are fractionized by the meshes of the net matter and the generation of large voids is inhibited. Accordingly, the phenomenon of a local temperature rise due to a reduction in the heat conductivity of a local part due to the existence of large voids can also be inhibited.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a semiconductor device, and particularly to a technology for manufacturing a semiconductor device with good heat dissipation properties.

[Background Art] Due to the demand for higher functionality and higher integration of semiconductor devices, the dimensions of semiconductor elements (chips) tend to become larger and the amount of heat generated during their operation tends to increase. Therefore, in order to ensure the reliability of a semiconductor device, it is necessary to quickly dissipate the heat generated in the chip during operation to the outside. 2. Description of the Related Art Computers and the like employ means for forcibly cooling a large number of built-in semiconductor devices using gas or liquid.

On the other hand, Japanese Patent Application No. 61-92032 discloses a technique for efficiently dissipating heat outside the package of a semiconductor device. The above-mentioned publication states that semiconductor pellets (chips) -
A semiconductor device is described in which the main surface and the back surface of the cap (inner wall surface of the package) are bonded with a gap-filling metal (joint body), that is, a low-melting brazing material. Note that the semiconductor pellet is CCB (Controlled Co1
1apse bonding) structure, in which a CCB bump, which is an electrode, is fixed to the main surface of a package substrate that constitutes a pan cage together with the cap.

[Problem to be solved by the invention]

A semiconductor device with a CCB structure is different from a structure in which the semiconductor element is directly fixed to the substrate, but is fixed to the substrate via CCB bumps, so the heat generated in the semiconductor element is transferred to the substrate via the CCB bumps, and the package is damaged. Dissipated to the outside. Therefore, in a semiconductor device having this type of structure, the heat transfer path area becomes small. In the structure disclosed in the above document, the top surface (back surface) of the semiconductor pellet without the CCB bump is connected to the back surface (inner wall surface) of the cap via the filling layer, thereby increasing the heat transfer path area. This improves heat dissipation.

Incidentally, in semiconductor devices having such a structure, some devices sometimes have poor heat dissipation properties, causing characteristic deterioration. As a result of analyzing and studying semiconductor devices that have suffered from such characteristic deterioration, the inventors have clarified the following facts.

In semiconductor devices whose characteristics have deteriorated, large cavities (voids) are found in the filling layer that connects the chip and the cap.
was recognized. In the manufacturing (assembly) of semiconductor devices,
A solder plate is stacked on the inner wall of the package, and
A semiconductor element is stacked on the solder plate, and the solder plate is heat-treated to bond the semiconductor element and the package.

At this time, the inner wall of the package and the back surface of the semiconductor element escape from between the back surface of the semiconductor element and the inner wall of the package, but some of it gets caught up and remains as bubbles in the solder layer (filling layer) that is the bonded body. According to the inventor's analysis, if each of the voids is fine and uniformly distributed over the entire bonding surface, the probability of property deterioration occurring is extremely low; however, if the voids are large voids. In this case, since there is air in the void area that does not necessarily have good heat transfer properties, heat dissipation cannot be performed smoothly in the area facing this large void, resulting in heat rise and deterioration of characteristics. I often put it away.

An object of the present invention is to provide a semiconductor device with good heat dissipation characteristics and a method for manufacturing the same.

The above and other objects and novel features of the present invention include:
It will become clear from the description of this specification and the accompanying drawings.

[Means to solve the problem]

A brief overview of typical inventions disclosed in this application is as follows.

That is, the semiconductor device of the present invention has a structure in which the back surface of a semiconductor element is connected to the inner wall surface of a cap of a ceramic package via solder, and the solder serves as a heat transfer body that transfers heat from the semiconductor element to the camp. In addition, a net is laid within the solder. The surface of this net is made of a material that has good wettability with solder, and is in good contact with solder.

In another embodiment of the present invention, the heat transfer body provided between the semiconductor element and the cap in the above embodiment is made of a material that is hardened at room temperature, but softens and melts at that temperature when the semiconductor element generates heat. has been done. Therefore, when the semiconductor element is driven, the heat transfer body softens and melts and comes into close contact with the back surface of the semiconductor element and the inner wall surface of the cap. Further, since the package is made of ceramic, the softened and molten substance is difficult to wet and is difficult to separate from between the back surface of the semiconductor element and the inner wall surface of the cap.

[Effect]

According to the above-mentioned means, in the semiconductor device of the present invention, the back surface of the semiconductor element and the inner wall surface of the cap are connected through the solder having good thermal conductivity, so that the heat generated in the semiconductor element is quickly transferred to the cap. transmitted to. In addition, since a mesh with good solder wettability is laid inside the solder, even if air gets caught in the solder and voids occur, the solder will wet the mesh well, and the mesh will Since the voids are divided, the voids are sufficiently smaller than the mesh of the net body. Therefore, large voids do not occur in a part of the heat transfer path, and it is possible to prevent a phenomenon where the temperature locally increases and the characteristics of the semiconductor element deteriorate.

In another embodiment, the heat transfer body is made of a substance that becomes solid at room temperature instead of the solder, but softens and melts at the temperature generated by the heat generated when driving the semiconductor element. Since the heat transfer body softens and melts and comes into close contact with the net, the back surface of the semiconductor element, and the inner wall surface of the cap, and furthermore, the voids are reduced by the action of the net, so that the heat transfer path is uniform over the entire surface. As a result, stable operation of the semiconductor device can be guaranteed.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic cross-sectional view showing essential parts of a semiconductor device according to an embodiment of the present invention, and FIG. 2 is a schematic cross-sectional view showing the manufacturing state of the semiconductor device.

The semiconductor device 1 of this embodiment, as shown in FIG. . The package 2 includes a base 4 having the electrode 3, and a bonding layer 5 made of a solder material on the main surface side of the base 4.
and a cap 6 fixed thereto. For example, inside the package 2,
High-speed E CL (Emitter-Coupled L
A semiconductor element (chip) 7 constituting the Logic) is disposed. The semiconductor element 7 has a large number of CCBs on one side.
A bump 8 is provided. These CCB bumps 8 are made of solder (PbSn), and have negative sides of, for example, 8.
In the rectangular chip 7 with ~10rr+m, 5
Approximately 00 to 600 are provided.

Such a chip 7 is fixed to the base 4 via the CCB bump 8. The base 4 is made of alumina ceramic and has a wiring board structure. Then, on one surface (inner surface) of the base 4, the C of the chip 7 is provided.
A pad 9 corresponding to the CB bump 8 is provided, and the electrode 3 is provided on the other surface (outer surface). Further, this electrode 3 and the pad 9 are connected to the base 4, a part of which is shown in the figure.
They are electrically connected via a wiring section 10 provided therein. The base 4 is specifically made of mullite (see 3A,
03 ・Made of 2SiO. This mullite has a thermal expansion coefficient α of 3.0
．． 5 x 10-'/''C. Therefore, even if the high-speed ECL operates and generates heat, most of the heat is generated between the chip 7 and the base 4, while the other surface of the chip 7 is connected to the bonded body 11.
It is fixed to the inner wall surface of the cap 6 via. The bonded body 11 is selected to have good adhesion to the chip 7 and the camp 6, and to have high thermal conductivity so that the heat generated by the chip 7 can be quickly transferred to the camp 6. Moreover, since this bonded body 11 is connected after the CCB bump 8 of the chip 7 is fixed to the base 4, when the bonded body 11 is connected, the CCB bump 8 of the chip 7 is connected to the base 4.
A low melting point metal such as solder (PbSn) that will not melt the bumps 8 is selected. In this case, the compositions of both solders are selected so that the melting point of the CCB bump 8 made of solder is higher than the melting point of the joined body 11.

On the other hand, in order to improve the adhesion between the bonded body 11 made of the solder and the inner wall surfaces of the chip 7 and the cap 6, the other surface of the chip 7 is made of Cr/Cu/
A metallization 1i12 made of Au is provided, and the inner wall surface of the cap 6 is made of Ti/Ni/Au.
A metallization N13 consisting of is provided. Note that the joined body 11 will also be referred to as a heat transfer body due to its function.

Further, which is one of the features of the present invention, a net 14 is disposed (laid) within the bonded body 11 (solder). When assembling a semiconductor device, if air is caught in the solder and bubbles (voids) are generated, this mesh body 14 subdivides the voids using the mesh to prevent the generation of large voids. play a role. therefore,
Due to the presence of the net 14, the voids are sufficiently smaller than the mesh of the net 14 and are dispersed by the net 14, so that the presence of large voids prevents a local temperature increase phenomenon due to a decrease in thermal conductivity in a local area. This also suppresses deterioration of the characteristics of the semiconductor element, and the semiconductor element operates stably.

On the other hand, the net 14 is made of a metal wire such as copper or gold, or a braided fiber such as glass fiber or plastic fiber. Further, in order to improve heat conductivity, it is necessary to select a mesh member 14 that does not inhibit at least heat conduction, and it is also necessary to improve the adhesion between the mesh member 14 and the bonded body 11. Net body 14 and the joined body 1
In order to improve the adhesion with the bonded body 11, the net body 14 is
The net member 14 may be made of a material that has good wettability with the bonded body 11, or the surface of the net member 14 may be coated with a substance that has good wettability with the bonded body 11. In this embodiment, the bonded body 11 is made of solder (PbSn), which is one of the low melting point metal materials.
) is used.

On the other hand, the mesh body 14 is required to have such elasticity that it can come into elastic contact with the back surface of the semiconductor element 7 and the inner wall surface of the cap 6, respectively. In this embodiment, a mesh body 14 knitted with gold wire is used.

Further, the mesh body 14 has the same size or larger (wider) size than the semiconductor element 7 in order to uniformly dissipate heat from the back surface of the semiconductor element 7 to the cap.

Furthermore, in order to subdivide the voids caused by the air when air is caught in the solder, a wire with a fine mesh is used to the extent that the solder can enter.

By the way, if the fibers constituting the net body 14 are made of a material itself that has good wettability with a low melting point metal, the low melting point metal material and the fiber material may react and the melting point increases; If an increase in the amount of heat is undesirable, it is preferable that the net body 14 is made of a thin coating of a material that has good wettability with respect to a low melting point metal. In this case, it is advisable to coat the material with an additive that has a high affinity for oxygen. The additives include Li and Ca.

Be, Mg, Au, Ba, Ti, Ta, S
, V, etc. are good, and the amount added is 0.1 to 2%.
is appropriate.

Next, a method for manufacturing (assembling) such a semiconductor device 1 will be explained with reference to FIG. First, a ceramic cap 6 is prepared and turned inside out. A metallized layer 13 is previously provided on the inner wall surface of the cap 6. Therefore, on this metallized layer 13, a network 14 as described above is placed. Solder plate 20. The bases 4, which are turned upside down and have the semiconductor element 7 attached to the center of the lower surface thereof, are successively stacked on top of each other. A metallized layer 12 is provided on the lower surface of the semiconductor element 7.

This metallized layer 12 faces the solder plate 20. The solder plate 20 is the semiconductor element 7
It is approximately the same size. Further, the mesh body 14 has the same size as the semiconductor element 7 or preferably has the same size as the semiconductor element 7.
It is slightly larger than the . Further, a bonding layer 5 is provided on the upper surface of the periphery of the can 160 so as to face the periphery of the base 4.

The articles stacked one after another in this way are heat treated. This heat treatment is performed during the CC process for bonding the semiconductor element 7 and the base 4.
Although the B bump 8 is not softened and melted, the bonding layer 5 and the solder plate 20 are softened and melted, and the base 4 and the cap 6 are hermetically sealed.
The inner wall surface of the semiconductor element 7 and the back surface of the semiconductor element 7 are bonded to each other.

At this time, the solder plate 20 is melted, and the molten solder is transferred to the net 14 extending between the inner wall surface of the cap 6 and the back surface of the semiconductor element 7.
Penetrates into the mesh. Therefore, air escapes from many of the meshes. Further, since the remaining air is separated by the net 14 and the solder is well wetted with the net 14, air bubbles (voids) are not generated over a wide area and the size of the generated voids is also small.

Therefore, the thermal resistance becomes uniform over the entire heat transfer path surface between the back surface of the semiconductor element 7 and the inner wall surface of the cap 6.

According to such an embodiment, the following effects can be obtained.

(1) In the semiconductor device of the present invention, since the back surface of the semiconductor element is fixed to the inner wall surface of the camp constituting the package via the heat transfer body, the heat generated in the semiconductor element is transferred via the heat transfer body. This has the effect that it can be dissipated outside the pan cage.

(2) In the semiconductor device of the present invention, a heat transfer body is disposed between the back surface of the semiconductor element and the inner wall surface of the cap, and since a mesh body is laid in this heat transfer body, The effect is that there are no large bubbles, only fine bubbles.

(3) In the semiconductor device of the present invention, as described above, a heat transfer body with a net laid between the semiconductor element and the cap is interposed, but the heat transfer body and the net are in close contact with each other. Since the materials are selected, the heat transfer body and the mesh body come into contact with each other without creating a gap at the interface, resulting in the effect that the thermal resistance is minimized.

(4) According to (1) to (3) above, in the semiconductor device of the present invention, a heat transfer body is disposed between the semiconductor element and the cap, and in this heat transfer body, heat generation occurs during formation of the heat transfer body. Since the wire is provided to subdivide the air bubbles, and the adhesion between the net and the heat transfer body is good, the heat transfer resistance is minimized and property deterioration due to heat is less likely to occur. A synergistic effect can be obtained.

(5) According to the method for manufacturing a semiconductor device of the present invention, when the back surface of the semiconductor element is bonded to the inner wall surface of the cap via solder (heat conductor), a mesh is formed between the back surface of the semiconductor element and the inner wall surface of the cap. Since the semiconductor element is fixed to the cap by melting the solder plate in this state, even if air is caught between the semiconductor element and the cap and air bubbles are formed, the air bubbles will be removed from each mesh of the mesh. Because the solder easily wets the mesh and fills the space within the mesh with solder, large bubbles do not form over a wide area, and even if bubbles do occur, they are uniform. This has the effect of Therefore, the thermal resistance of the heat transfer body is made uniform over the entire region, so that the semiconductor device is less likely to be deteriorated by the heat generated during operation of the semiconductor device.

(6) In manufacturing the semiconductor device of the present invention, at least the surface of the net is made of a material that has good wettability with the solder that serves as the heat transfer body, so that it has good wettability with the heat transfer body. The effect is that the adhesion is improved and a semiconductor device with good heat dissipation characteristics can be manufactured.

(7) In the method for manufacturing a semiconductor device of the present invention, the operation of forming a heat transfer body between the semiconductor element and the cap includes a mesh body and a solder plate (
By sandwiching the heat conductor forming material) and then applying heat to soften and melt the solder plate, it is possible to easily form the solder plate.

(8) According to the above (1) to (7), according to the present invention, a synergistic effect is obtained in that a semiconductor device that can efficiently dissipate heat generated in a semiconductor element to the outside of the package can be manufactured at a low cost.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the above Examples and can be modified in various ways without departing from the gist thereof. For example, the positional relationship between the solder plate 20 and the net 14 shown in FIG. 2 may be reversed, and as shown in FIG. The bonded body 11 to be formed, that is, the heat transfer body 11, may be made of a material that is solid at room temperature but softens and melts with the heat generated by the semiconductor element 7 when the semiconductor element 7 is in operation. Now, the melted heat transfer body 11
Since it is in direct contact with the back surface of the semiconductor element 7, the inner wall surface of the cap 6, and the mesh body 14, the heat generated in the semiconductor element can be quickly dissipated over the entire area. Examples of materials that soften and melt during operation include 50% Bi and Pb.
is 30%, Sn is 20%, and has a melting point of 92°C.
Bi is 50%, Pb is 25%, and Sn is 12.5%.

What is called a wood alloy with a melting point of 60°C where Cd is 12.5%, Bi is 49.4%, Pb is 18%, and S
A material with a melting point of 58° C. in which n is 11.6% and indium is 21% is used. Although it is not preferable for the heat transfer body 11 to boil at the temperature used to seal the base 4 and the cap 6, any material that softens and melts during operation is used for the seal that joins the base 4 and the cap 6. It does not cause boiling phenomenon when stopped.

Note that the material that softens and melts during operation has poor wettability with the silicon of the semiconductor element and the ceramic that is the base material of the cap, so it will not overflow from between the back surface of the semiconductor element 7 and the inner wall surface of the cap 6. There aren't many. However, if it overflows and flows into the CCB bump 8 side, there is a risk that the spaces between the CCB bumps 8 will be coated. The outer portion of the bump 8 may be covered with an insulating material 21 by vapor deposition or the like. Even if the insulating substance 21 is coated with insulating silicone oil or the like, the same effect as in the above embodiment can be obtained.

Although the surface mount structure has been described in the above embodiment, the same effects as in the above embodiment can be obtained with other pancage structures.

In the above explanation, the invention made by the present inventor was mainly applied to the manufacturing technology of surface-mounted semiconductor devices, which is the background field of application, but the invention is not limited to this. It can also be applied to the manufacturing technology of semiconductor devices having a uniform structure.

〔Effect of the invention〕

A brief explanation of the effects obtained by typical inventions disclosed in this application is as follows.

In the semiconductor device of the present invention, a heat transfer body is disposed between the semiconductor element and the cap, and a net is provided in the heat transfer body to subdivide air bubbles generated when the heat transfer body is shaped. Since the mesh body and the heat transfer body have a structure in which they are in close contact with each other, heat transfer resistance is minimized and heat dissipation performance is increased. Therefore, in the semiconductor device of the present invention, characteristic deterioration due to heat is less likely to occur.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view showing the main parts of a semiconductor device according to an embodiment of the present invention, FIG. 2 is a schematic sectional view showing the manufacturing state of the semiconductor device, and FIG. 3 is another embodiment of the present invention. 1 is a schematic cross-sectional view showing a main part of a semiconductor device according to an example. DESCRIPTION OF SYMBOLS 1... Semiconductor device, 2... Package, 3... Electrode, 4... Base, 5... Bonding layer, 6... Cap, 7... Semiconductor element, 8... CCB Bump, 9・
...Pad, 10...Wiring part, 11...Joint body (heat conductor), 12...Metallized layer, 13...Metallized layer, 14...Network, 20...Solder board , 21...
Insulating substance. Fig. 1 Fig. 2 Fig. 2 - Bab cage 6 - Header - f7゜8 - CCB bumper 14 - Base case 4 - Base 7 - Child guide bundle 11 - Jiang Heban 20 - Hayata cane

Claims (1)

[Claims] 1. A semiconductor device in which one side of a semiconductor element is fixed to an inner wall surface of a package via a bonded body, wherein a bubble dispersion is laid in the bonded body between the semiconductor element and the package. A semiconductor device characterized by: 2. The semiconductor device according to claim 1, wherein the bubble dispersion is formed of a net. 3. The semiconductor device according to claim 1, wherein the bubble dispersion is made of a substance that becomes molten at a temperature during operation of the semiconductor element. 4. The semiconductor device according to any one of claims 1 to 3, wherein at least the surface of the bubble dispersion is made of a material that has good wettability with the bonded body. 5. Sequentially stack the bonded body and the semiconductor element on the inner wall surface of the package, then perform heat treatment to melt the bonded body,
A method for manufacturing a semiconductor device in which a semiconductor element is fixed to an inner wall surface of a package using the bonded body, wherein a bubble dispersion is interposed when the bonded body is interposed between the inner wall surface of the package and the semiconductor element, and then the A method of manufacturing a semiconductor device, comprising: fixing the semiconductor element to an inner wall surface of the package by melting a bonded body.