Semiconductor device and method of manufacturing the same

Abstract

The upper surface of the heat dissipation plate (5) is provided with a groove (6) along the outer periphery of the insulating substrate (1). The first solder bonding material (7) is filled in the groove (6). A second solder bonding material (8) is provided on the upper surface of the heat dissipation plate (5) and on the first solder bonding material (7), and bonds the upper surface of the heat dissipation plate (5) and the first metal pattern (1b). The types of the first solder bonding material (7) and the second solder bonding material (8) are different. The melting point of the first solder bonding material (7) filled in the groove (6) is lower than the melting point of the second solder bonding material (8).

Description

Technical Field

[0001] The present invention relates to a semiconductor device and a method for manufacturing the same. Background Art

[0002] In semiconductor power modules, solder bonding materials are used when bonding an insulating substrate to a heat sink. To improve the thermal fatigue resistance of the solder bonding materials, it has been proposed to provide grooves in the heat sink along the outer periphery of the insulating substrate (see, for example, Patent Document 1).

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 9-252082 Summary of the invention

[0004] By filling the groove with solder bonding material, the solder bonding material can be thickened at the outer periphery of the insulating substrate. Therefore, the thermal stress generated when the semiconductor device is in operation and the generation of cracks in the solder bonding material caused by the stress of the insulating substrate and the semiconductor chip can be suppressed. However, there is a problem that solder voids are generated in the groove, which reduces the reliability of the semiconductor device.

[0005] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to obtain a semiconductor device and a method for manufacturing the same that can improve reliability.

[0006] The semiconductor device according to the present invention is characterized in that it comprises: an insulating substrate having an insulating layer, a first metal pattern provided on the lower surface of the insulating layer, and a second metal pattern provided on the upper surface of the insulating layer; a semiconductor chip bonded to the second metal pattern; a heat sink provided under the insulating substrate and having a groove provided on the upper surface along the outer periphery of the insulating substrate; a first solder bonding material filled in the groove; and

[0007] A second solder bonding material is arranged on the upper surface of the heat sink and the first solder bonding material to bond the upper surface of the heat sink and the first metal pattern. The first solder bonding material and the second solder bonding material are of different types, and the melting point of the first solder bonding material is lower than the melting point of the second solder bonding material.

[0008] Effects of the Invention

[0009] In the present invention, different types of solder bonding materials are used as the first solder bonding material and the second solder bonding material, and the melting point of the first solder bonding material filled in the groove is lower than that of the second solder bonding material. Therefore, bubbles in the first solder bonding material are eluted from the first solder bonding material during reflow, so that bubbles in the first solder bonding material move upward from the groove due to pressure from above. As a result, solder voids in the groove are reduced, thereby improving reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is a cross-sectional view showing a semiconductor device according to an embodiment.

[0011] Figure 2 It is a plan view showing a heat sink and an insulating substrate according to the embodiment.

[0012] Figure 3 It is a cross-sectional view showing a method for manufacturing a semiconductor device according to an embodiment.

[0013] Figure 4 It is a cross-sectional view showing a method for manufacturing a semiconductor device according to an embodiment.

[0014] Figure 5 It is a cross-sectional view showing a modified example of the method for manufacturing the semiconductor device according to the embodiment.

[0015] Figure 6 It is a cross-sectional view showing a modified example of the method for manufacturing the semiconductor device according to the embodiment. DETAILED DESCRIPTION

[0016] Figure 1 is a cross-sectional view showing a semiconductor device according to an embodiment. Figure 2 1 is a top view showing a heat sink and an insulating substrate according to an embodiment. The insulating substrate 1 has an insulating layer 1a, a first metal pattern 1b provided on the lower surface of the insulating layer 1a, and a second metal pattern 1c provided on the upper surface of the insulating layer 1a. The semiconductor chip 3 is bonded to the second metal pattern 1c of the insulating substrate 1 by a solder bonding material 4. The heat sink 5 is provided under the insulating substrate 1. The material of the heat sink 5 is, for example, copper.

[0017] A groove 6 is provided on the upper surface of the heat sink 5 along the outer periphery of the insulating substrate 1. The insulating substrate 1 is a quadrilateral in a plan view, and the groove 6 is a square frame. The inner periphery of the groove 6 is located inside the outer periphery of the insulating substrate 1 in a plan view, and the outer periphery of the groove 6 is consistent with the outer periphery of the insulating substrate 1 or is located outside the outer periphery.

[0018] The groove 6 is filled with the first solder bonding material 7. The second solder bonding material 8 is provided on the upper surface of the heat sink 5 and the first solder bonding material 7, and bonds the upper surface of the heat sink 5 and the first metal pattern 1b.

[0019] By filling the groove 6 with the first solder bonding material 7, the solder bonding material can be thickened at the periphery of the insulating substrate 1. Therefore, the generation of cracks in the solder bonding material caused by thermal stress generated when the semiconductor device operates and stress of the insulating substrate 1 and the semiconductor chip 3 can be suppressed.

[0020] The interval between the upper surface of the heat sink 5 and the first metal pattern 1b is set to H, and the interval between the bottom surface of the groove 6 and the first metal pattern 1b is set to L, satisfying L>2H. As a result, the thickness of the solder bonding material on the periphery of the insulating substrate 1 is twice as thick as before, so that stress can be relieved and the generation of cracks can be suppressed. In addition, since the thickness of the solder bonding material under the semiconductor chip 3 is the same as before, the heat dissipation performance will not be reduced.

[0021] Next, a method for manufacturing the semiconductor device according to the embodiment will be described. Figure 3 , 4 2 is a cross-sectional view showing a method for manufacturing a semiconductor device according to an embodiment of the present invention. Figure 3 As shown in FIG. 1 , the cut solder is placed along the groove 6 provided on the upper surface of the heat sink 5 as the first solder bonding material 7. Figure 4 As shown, the cut solder is placed on the upper surface of the heat sink 5 and the first solder bonding material 7 as the second solder bonding material 8. Next, the insulating substrate 1 is placed on the second solder bonding material 8 in a manner that the groove 6 is arranged along the outer periphery of the insulating substrate 1, and the first solder bonding material 7 and the second solder bonding material 8 are reflowed to bond the upper surface of the heat sink 5 to the first metal pattern 1b. Next, the semiconductor chip 3 is bonded to the second metal pattern 1c. The semiconductor device according to the embodiment is manufactured through the above steps.

[0022] Figure 5 , 6 1 is a cross-sectional view showing a modified example of the method for manufacturing a semiconductor device according to the embodiment. Figure 5 As shown in FIG. 1 , a paste solder is applied along the groove 6 as the first solder bonding material 7. Figure 6 As shown, the cut solder is placed on the upper surface of the heat sink 5 and the first solder bonding material 7 as the second solder bonding material 8. The subsequent steps are the same as described above. In this way, by placing the first solder bonding material 7 in the groove 6 and then placing the second solder bonding material 8, solder bonding materials of different materials can be loaded.

[0023] In the present embodiment, different types of solder bonding materials are used as the first solder bonding material 7 and the second solder bonding material 8, and the melting point of the first solder bonding material 7 filled in the groove 6 is lower than the melting point of the second solder bonding material 8. Therefore, bubbles in the first solder bonding material 7 are eluted from the first solder bonding material 7 during reflow, so the bubbles in the first solder bonding material 7 move upward from the groove 6 by the pressure from above. As a result, the solder voids inside the groove 6 are reduced, so the reliability can be improved. In addition, after reflow, the voids of the second solder bonding material 8 on the heat sink 5 can also be confirmed from the surface, so they can be corrected by rework from the outside.

[0024] In addition, the semiconductor chip 3 is not limited to being formed by silicon, but can also be formed by a wide bandgap semiconductor having a larger bandgap than silicon. Wide bandgap semiconductors are, for example, silicon carbide, gallium nitride materials, or diamond. Since the pressure resistance and allowable current density of the semiconductor chip formed by such a wide bandgap semiconductor are high, it can be miniaturized. By using the miniaturized semiconductor chip, the semiconductor device assembled with the semiconductor chip can also be miniaturized and highly integrated. In addition, since the semiconductor chip has high heat resistance, the heat sink fins of the radiator can be miniaturized, and the water cooling part can be set to air cooling, so the semiconductor device can be further miniaturized. In addition, since the power loss of the semiconductor chip is low and efficient, the semiconductor device can be made efficient.

[0025] Description of the label

[0026] 1 insulating substrate, 1a insulating layer, 1b first metal pattern, 1c second metal pattern, 3 semiconductor chip, 5 heat sink, 6 groove, 7 first solder bonding material, 8 second solder bonding material.

Claims

1. A semiconductor device, characterized in that: have: An insulating substrate having an insulating layer, a first metal pattern disposed on a lower surface of the insulating layer, and a second metal pattern disposed on an upper surface of the insulating layer; a semiconductor chip bonded to the second metal pattern; A heat sink is disposed under the insulating substrate and has a groove on its upper surface along the outer periphery of the insulating substrate; a first solder bonding material filled in the groove; as well as a second solder bonding material provided on the upper surface of the heat sink and the first solder bonding material to bond the upper surface of the heat sink to the first metal pattern; The first solder bonding material and the second solder bonding material are of different types, The melting point of the first solder bonding material is lower than the melting point of the second solder bonding material.

2. The semiconductor device according to claim 1, wherein: The distance between the upper surface of the heat sink and the first metal pattern is set to H, and the distance between the bottom surface of the groove and the first metal pattern is set to L, and L>2H is satisfied.

3. The semiconductor device according to claim 1 or 2, characterized in that: The semiconductor chip is formed of a wide bandgap semiconductor.

4. A method for manufacturing a semiconductor device, characterized in that: The process is as follows: disposing a first solder bonding material in a groove provided on an upper surface of a heat sink; disposing a second solder bonding material on the upper surface of the heat sink and on the first solder bonding material; placing the insulating substrate on the second solder bonding material in a manner that the grooves are arranged along the periphery of the insulating substrate, and reflowing the first solder bonding material and the second solder bonding material to bond the upper surface of the heat sink to the first metal pattern, the insulating substrate comprising an insulating layer, the first metal pattern provided on the lower surface of the insulating layer, and the second metal pattern provided on the upper surface of the insulating layer; as well as bonding a semiconductor chip to the second metal pattern, The first solder bonding material and the second solder bonding material are of different types, The melting point of the first solder bonding material is lower than the melting point of the second solder bonding material.

5. The method for manufacturing a semiconductor device according to claim 4, wherein: A cut solder is placed along the groove as the first solder bonding material.

6. The method for manufacturing a semiconductor device according to claim 4, wherein: Cream solder is applied along the groove as the first solder bonding material.

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