Semiconductor device and method for manufacturing semiconductor device

Abstract

The purpose of the present invention is to provide a technology capable of suppressing the occurrence of bonding failure caused by positional deviation of a conductive bonding material in a semiconductor device. A semiconductor device 100 comprises a semiconductor element 3 and a metal lead electrode 1 bonded onto the semiconductor element 3 by using a conductive bonding material 2a. The metal lead electrode 1 comprises: a through-hole 1a penetrating from a first surface to a second surface of the metal lead electrode 1; a bondable region 10 that is provided on the outer periphery of the through-hole 1a on at least one of the first surface and the second surface and is bondable to the conductive bonding material 2a; and a bonding prevention region 11 that is provided on the outer periphery of the bondable region 10 on at least one of the first surface or the second surface and prevents bonding to the conductive bonding material 2a.

Description

Semiconductor device and method for manufacturing a semiconductor device

[0001] The present disclosure relates to a semiconductor device and a method for manufacturing a semiconductor device.

[0002] In Patent Document 1, it is proposed to suppress solder wetting spread and improve the manufacturability of a semiconductor device by forming a surface coating layer with poor solder wettability over the entire area excluding the joint portion of a metal lead electrode or in a frame shape surrounding the joint portion.

[0003] Japanese Patent Application Laid-Open No. 2008-270290

[0004] However, in the technique described in Patent Document 1, when a joining method is adopted in which a hole is provided in the joint portion of a metal lead electrode and a conductive joining material (e.g., solder, etc.) melted from above is supplied, displacement is likely to occur in the supply position of the conductive joining material. In this case, there is a problem that the conductive joining material is not supplied to the joint portion, resulting in a joining failure and deterioration of the manufacturability of the semiconductor device.

[0005] Therefore, an object of the present disclosure is to provide a technique capable of suppressing the occurrence of joining failures caused by displacement of a conductive joining material in a semiconductor device.

[0006] The semiconductor device according to the present disclosure includes a semiconductor element and a metal lead electrode joined to the semiconductor element by a conductive joining material. The metal lead electrode includes a through hole penetrating from a first surface to a second surface of the metal lead electrode, a joinable region provided on an outer periphery of the through hole on at least one of the first surface and the second surface and capable of being joined to the conductive joining material, and a joining prevention region provided on an outer periphery of the joinable region on at least the one of the first surface and the second surface and preventing joining to the conductive joining material.

[0007] According to this disclosure, since a bondable region is provided on the outer circumference of the through hole on at least one of the first and second surfaces of the metal lead electrode, even if a misalignment occurs in the supply position of the conductive bonding material, the conductive bonding material will spread and wet in the bondable region, causing it to flow into the through hole and be positioned between the metal lead electrode and the semiconductor element. This makes it possible to suppress the occurrence of bonding defects caused by misalignment of the conductive bonding material.

[0008] The purpose, features, aspects, and benefits of this disclosure will become clearer from the following detailed description and accompanying drawings.

[0009] Figure 1 is a cross-sectional view of a semiconductor device according to Embodiment 1. Figure 2 is a top view of a semiconductor device according to Embodiment 1. Figure 3 is a cross-sectional view of a semiconductor device according to Embodiment 2. Figure 4 is a top view of a semiconductor device according to Embodiment 2.

[0010] <Embodiment 1> Embodiment 1 will be described below with reference to the drawings. Figure 1 is a cross-sectional view of the semiconductor device 100 according to Embodiment 1. Figure 2 is a top view of the semiconductor device 100 according to Embodiment 1.

[0011] As shown in Figures 1 and 2, the semiconductor device 100 comprises a heat dissipation member 4, a semiconductor element 3, and a metal lead electrode 1.

[0012] The heat dissipation member 4 is made of a metal material with excellent thermal conductivity, such as copper. The semiconductor element 3 is joined to the upper surface of the heat dissipation member 4 by solder or a conductive bonding material 2b such as sintered silver. The metal lead electrode 1 is joined to the upper surface of the semiconductor element 3 by solder or a conductive bonding material 2a such as sintered silver.

[0013] The metal lead electrode 1 includes a through hole 1a, a bonding region 10, and a bonding prevention region 11.

[0014] The through-hole 1a penetrates from the upper surface (corresponding to the first surface) to the lower surface (corresponding to the second surface) of the metal lead electrode 1. The conductive bonding material 2a is placed between the semiconductor element 3 and the metal lead electrode 1 through the through-hole 1a.

[0015] The joinable region 10 is a region that can be joined with the conductive joining material 2a, and is provided on the outer circumference of the through hole 1a on at least one of the upper and lower surfaces of the metal lead electrode 1. Specifically, the joinable region 10 is provided on the upper and lower surfaces of the metal lead electrode 1 so as to surround the outer circumference of the through hole 1a and has a frame shape. The diameter of the joinable region 10 is 10 mm or less. Here, the region including the through hole 1a and the joinable region 10 is the joint portion of the metal lead electrode 1. No protective film or roughened region is provided at the joint portion of the metal lead electrode 1, and the surface of the metal lead electrode 1 is exposed.

[0016] If the diameter of the bondable area 10 exceeds 10 mm, the area over which the conductive bonding material 2a spreads becomes larger, increasing the amount of conductive bonding material 2a required, and also making the bond with the semiconductor element 3 unstable. Therefore, a deterioration in the manufacturability of the semiconductor device 100 is expected. By limiting the size of the diameter of the bondable area 10, it becomes possible to control the area over which the conductive bonding material 2a spreads. Furthermore, as long as the bondable area 10 surrounds the through hole 1a and has a diameter of 10 mm or less, there are no restrictions on its shape; it may be rectangular or annular.

[0017] The bonding prevention region 11 is a region that prevents bonding with the conductive bonding material 2a and is equipped with a protective film. The bonding prevention region 11 is provided on the outer circumference of the bondable region 10 on at least one of the upper and lower surfaces of the metal lead electrode 1. Specifically, the bonding prevention region 11 is provided over the entire area outside the bondable region 10 on the upper and lower surfaces of the metal lead electrode 1. The bonding prevention region 11 is formed by, for example, placing a resist in the bondable region 10 of the metal lead electrode 1 and applying a protective film to the entire metal lead electrode 1. The material, surface condition, and formation method of the bondable region 10 and the bonding prevention region 11 are not limited.

[0018] Furthermore, both the joinable region 10 and the non-joining region 11 may be provided on one of the upper and lower surfaces of the metal lead electrode 1. In this case, the joinable region 10 and the non-joining region 11 are provided on the same surface of the metal lead electrode 1.

[0019] The heat dissipation member 4 may be made of a single metal, or it may be made of an insulating substrate comprising a metal with excellent thermal conductivity and a ceramic such as silicon nitride or aluminum nitride that has insulating properties and a predetermined strength.

[0020] The semiconductor element 3 may be composed of a semiconductor such as Si, or a wide-bandgap semiconductor such as SiC or GaN. The semiconductor element 3 includes, for example, an IGBT (Insulated Gate Bipolar Transistor), a MOSFET (Metal Oxide Semiconductor Field Effect Transistor), or a Schottky barrier diode. The quantity and shape of the semiconductor element 3 are not limited and may be determined according to the application.

[0021] Similarly, the joint portion of the metal lead electrode 1 may also be in any quantity and shape as needed.

[0022] Next, the assembly procedure for the semiconductor device 100 according to Embodiment 1 will be described. First, the semiconductor element 3 is joined to the circuit pattern provided on the heat dissipation member 4 using a conductive bonding material 2b. Generally, solder or sintered silver is often used as the conductive bonding material 2b. When solder is used as the conductive bonding material 2a, a solder plate or solder paste is placed on the circuit pattern, and the semiconductor element 3 is placed on top of it. The components assembled in the above steps are heated to a temperature exceeding the melting point of the solder in a semiconductor manufacturing apparatus, and the joining is completed by cooling.

[0023] Next, the components joined in the above process are joined to the metal lead electrode 1. Solder or sintered silver is often used as the conductive bonding material 2a. When solder is used as the conductive bonding material 2a, a solder sheet or paste is placed on the semiconductor element 3, and with the solder in contact with the joint of the metal lead electrode 1, the temperature is raised in the semiconductor manufacturing apparatus to a temperature exceeding the melting point of the solder. The joining is then completed by cooling. Alternatively, a method of joining by applying high-temperature molten solder from above the joint of the metal lead electrode 1 using a glass syringe or the like may also be employed.

[0024] As described above, in Embodiment 1, the semiconductor device 100 comprises a semiconductor element 3 and a metal lead electrode 1 bonded to the semiconductor element 3 by a conductive bonding material 2a. The metal lead electrode 1 comprises a through hole 1a that penetrates from the upper surface to the lower surface of the metal lead electrode 1, a bondable region 10 provided on the outer circumference of the through hole 1a on at least one of the upper and lower surfaces and capable of bonding with the conductive bonding material 2a, and a bonding prevention region 11 provided on the outer circumference of the bondable region 10 on at least one of the upper and lower surfaces and preventing bonding with the conductive bonding material 2a. Specifically, both the bondable region 10 and the bonding prevention region 11 are provided on the upper and lower surfaces.

[0025] Therefore, since a bonding region 10 is provided on the outer circumference of the through hole 1a on the upper and lower surfaces of the metal lead electrode 1, even if a misalignment occurs in the supply position of the conductive bonding material 2a, the conductive bonding material 2a will spread and wet in the bonding region 10, causing the conductive bonding material 2a to flow into the through hole 1a and be positioned between the metal lead electrode 1 and the semiconductor element 3. This makes it possible to suppress the occurrence of bonding defects caused by misalignment of the conductive bonding material 2a.

[0026] Furthermore, since the bonding prevention region 11 is provided on the upper and lower surfaces of the metal lead electrode 1 around the outer circumference of the bondable region 10, it is possible to suppress the conductive bonding material 2a from wetting and spreading to the outer circumference of the bondable region 10. This improves the manufacturability of the semiconductor device 100.

[0027] Furthermore, the joinable region 10 has a frame-like shape that surrounds the outer circumference of the through hole 1a, and the diameter of the joinable region 10 is 10 mm or less. The bond prevention region 11 is provided over the entire area outside the joinable region 10 of the metal lead electrode 1.

[0028] Therefore, by limiting the diameter of the bondable region 10, it becomes possible to control the area in which the conductive bonding material 2a wets and spreads. This makes it possible to quantify the required amount of conductive bonding material 2a, thereby reducing component costs. As a result, the manufacturability of the semiconductor device 100 can be improved.

[0029] <Embodiment 2> Next, Embodiment 2 will be described. Figure 3 is a cross-sectional view of the semiconductor device 100A according to Embodiment 2. Figure 4 is a top view of the semiconductor device 100A according to Embodiment 2. In Embodiment 2, the same reference numerals are used for components that are the same as those described in Embodiment 1, and their descriptions are omitted.

[0030] As shown in Figures 3 and 4, the shape of the bonding prevention region 11 in Embodiment 2 is different from that in Embodiment 1. Specifically, the bonding prevention region 11 has a frame shape that surrounds the outer circumference of the bondable region 10 and includes a roughened region. The roughened region may be formed by roughening the metal lead electrode 1 by press processing, or by roughening the metal lead electrode 1 by laser irradiation processing.

[0031] Furthermore, the shape of the bonding prevention region 11 is not restricted as long as it is formed to surround the outer periphery of the bonding-possible region 10, and it may be rectangular, annular, or grid-like. Also, the depth of the bonding prevention region 11 may be any depth as long as it does not exceed the thickness of the metal lead electrode 1.

[0032] As described above, in Embodiment 2, the joinable region 10 has a frame shape that surrounds the outer circumference of the through hole 1a, and the diameter of the joinable region 10 is 10 mm or less. The non-joining region 11 has a frame shape that surrounds the outer circumference of the joinable region 10.

[0033] Therefore, by limiting the diameter of the joinable area 10, it becomes possible to control the area in which the conductive bonding material 2a wets and spreads. This makes it possible to quantify the amount of conductive bonding material 2a required, thereby reducing component costs. Furthermore, by limiting the shape of the non-joining area 11, the cost of forming the non-joining area 11 is reduced, and the flow time of the conductive bonding material 2a is shortened.

[0034] Based on the above, the manufacturability of the semiconductor device 100A can be improved.

[0035] Furthermore, the bonding prevention region 11 includes a roughened region. The roughened region is formed by roughening the metal lead electrode 1 through press working. Therefore, no additional material is required, as is the case with protective films, and since press working is relatively easy, it is possible to reduce manufacturing costs.

[0036] Furthermore, when a roughened region is formed by roughening the metal lead electrode 1 by laser irradiation, no additional material such as a protective film is required, and it becomes possible to improve the degree of freedom during processing compared to when press processing is performed.

[0037] Although this disclosure has been described in detail, the above description is illustrative and not limiting in all respects. It is understood that countless variations not illustrated are conceivable.

[0038] Furthermore, it is possible to freely combine each embodiment, or to modify or omit each embodiment as appropriate.

[0039] 1 Metal lead electrode, 1a Through hole, 2a Conductive bonding material, 3 Semiconductor element, 10 Bondable region, 11 Bonding prevention region, 100, 100A Semiconductor device.

Claims

1. A semiconductor device comprising: a semiconductor element; and a metal lead electrode bonded to the semiconductor element by a conductive bonding material, wherein the metal lead electrode comprises: a through hole penetrating from a first surface to a second surface of the metal lead electrode; a bondable region provided on the outer circumference of the through hole on at least one of the first surface and the second surface, which is capable of bonding with the conductive bonding material; and a bond prevention region provided on the outer circumference of the bondable region on at least one of the first surface and the second surface, which prevents bonding with the conductive bonding material.

2. The semiconductor device according to claim 1, wherein both the bondable region and the bond prevention region are provided on the first surface and the second surface.

3. The semiconductor device according to claim 1 or claim 2, wherein the bondable region has a frame shape that surrounds the outer circumference of the through hole, the diameter of the bondable region is 10 mm or less, and the bond prevention region is provided over the entire area outside the bondable region of the metal lead electrode.

4. The semiconductor device according to claim 1 or claim 2, wherein the bondable region has a frame shape surrounding the outer circumference of the through hole, the diameter of the bondable region is 10 mm or less, and the bond prevention region has a frame shape surrounding the outer circumference of the bondable region.

5. The semiconductor device according to claim 3, wherein the bonding prevention region is provided with a protective film.

6. The semiconductor device according to claim 4, wherein the bonding prevention region comprises a roughened region.

7. A method for manufacturing a semiconductor device according to claim 6, comprising forming the roughened region by roughening the metal lead electrode by press working.

8. A method for manufacturing a semiconductor device according to claim 6, comprising forming the roughened region by roughening the metal lead electrode by laser irradiation.

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