Semiconductor device and power conversion device using same

Abstract

The present invention provides a semiconductor device using a semiconductor chip in which a plurality of electrode pads are arranged close to each other on the same surface, said device being capable of suppressing a local temperature rise in the semiconductor chip. Provided is a semiconductor device including a gate electrode and a source electrode on a main surface of a semiconductor element, the gate wiring being connected to the gate electrode by wire bonding, and a source conductor being bonded to the source electrode via a conductive bonding material, the semiconductor being characterized in that: in a plan view viewed from the thickness direction of the semiconductor element, the source electrode includes a first electrode region that is adjacent to the gate electrode along one side of the semiconductor element where the gate wiring intersects, and a second electrode region that is adjacent to the gate electrode and the first electrode region and has an area larger than that of the first electrode region; the bonding material is in contact with the first electrode region and the second electrode region; and a contact region between the bonding material and the source conductor is formed so as to not overlap with the first electrode region and to overlap with the second electrode region in the plan view.

Description

Semiconductor device and power conversion device using the same , ,

[0004] ,

[0005]

[0001] The present invention relates to the structure of a semiconductor device, and more particularly to a technique effective when applied to a power semiconductor module using a semiconductor chip in which a plurality of electrode pads are arranged in proximity on the same surface.

[0002] In recent years, in order to reduce the environmental load, the spread of hybrid vehicles and electric vehicles has been promoted. In hybrid vehicles and electric vehicles, miniaturization and cost reduction of mounted components are emphasized, and semiconductor devices used in power conversion devices are no exception, and miniaturization and cost reduction are required.

[0003] In order to miniaturize a semiconductor device that generates a large amount of heat among the electronic components constituting a power conversion device, it is necessary to improve the cooling performance. For example, Patent Document 1 discloses a semiconductor device capable of radiating heat including the outer peripheral portion of a semiconductor chip.

[0004] Japanese Patent Application Laid-Open No. 2007-27308

[0005] According to the above Patent Document 1, by making the area of the metal component larger than the area of the active region of the semiconductor chip and smaller than the area of the main electrode of the semiconductor chip, the metal component and the main electrode can be satisfactorily fixed via the solder layer, and heat can be efficiently radiated including the outer peripheral portion of the semiconductor chip. It is said that a semiconductor device with high heat radiation efficiency can be provided by being able to efficiently radiate heat including the outer peripheral portion of the semiconductor chip.

[0006] However, in some cases, small semiconductor elements such as SiC power semiconductor elements are used, where the active region extends to the side of the gate electrode pad, and the source electrode pad is located within this extended active region. In this case, the connection area of ​​the source conductor, which is connected to the source electrode that occupies most of the area on the surface electrode side of the semiconductor element, takes on a rectangular shape that avoids the gate electrode pad and the source electrode pad, and the conductor connection area of ​​the surface electrode becomes smaller compared to the active region. In the parts where the source conductor is not connected, heat dissipation of the semiconductor element becomes difficult. In power semiconductor modules using power semiconductor elements such as SiC, if the operating temperature of the element rises, there is a concern that reliability will decrease due to the breakage of bonding wires during power cycles in which the chip is repeatedly turned ON and OFF.

[0007] Therefore, the object of the present invention is to provide a semiconductor device that can suppress local temperature rise within a semiconductor chip, in a semiconductor device using a semiconductor chip in which a plurality of electrode pads are arranged in close proximity on the same surface, and a power conversion device using the same.

[0008] To solve the above problems, the present invention provides a semiconductor device having a gate electrode and a source electrode on the main surface of a semiconductor element, wherein a gate wiring is connected to the gate electrode by wire bonding, and a source conductor is bonded to the source electrode via a conductive bonding material, wherein the source electrode has, in a plan view as seen from the thickness direction of the semiconductor element, a first electrode region adjacent to the gate electrode along one side of the semiconductor element where the gate wiring intersects, and a second electrode region adjacent to the gate electrode and the first electrode region, and having a larger area than the first electrode region, and the bonding material is in contact with the first electrode region and the second electrode region, and the contact region between the bonding material and the source conductor is formed such that, in the plan view, it does not overlap with the first electrode region but overlaps with the second electrode region.

[0009] According to the present invention, in a semiconductor device using a semiconductor chip in which multiple electrode pads are arranged in close proximity on the same surface, it is possible to realize a semiconductor device that can suppress local temperature rise within the semiconductor chip and a power conversion device using the same.

[0010] This can contribute to improving the reliability of semiconductor devices and power converters.

[0011] Other issues, configurations, and effects not mentioned above will be clarified by the following description of the embodiments.

[0012] This is a plan view (top view) of an electrical circuit body according to Embodiment 1 of the present invention. This is a cross-sectional view of the electrical circuit body 400 in Figure 1 along the line X-X'. This is a cross-sectional perspective view of the electrical circuit body 400 in Figure 1 along the line Y-Y'. This is a plan view (top view) of the semiconductor device 300 in Figure 1. This is a semi-transparent plan view of the semiconductor device 300 in Figure 4. This is an equivalent circuit diagram of the semiconductor device 300 in Figure 4. This is a plan view showing the arrangement of the source-side bonding material 160 of the semiconductor element 155 in Figure 5. This is a cross-sectional view of the line A-A' in Figure 7A. This is a cross-sectional view showing the method of forming the source-side bonding material 160 in Figure 7B. This is a plan view (top view) of a semiconductor device 300 according to Embodiment 2 of the present invention. This is a semi-transparent plan view of the semiconductor device 300 in Figure 9. This is a semi-transparent plan view of a semiconductor device 300 according to Embodiment 3 of the present invention. This is a semi-transparent plan view of a semiconductor device 300 according to Embodiment 4 of the present invention. This is a cross-sectional view of an electrical circuit body 100 according to Embodiment 5 of the present invention. Figure 13 is a plan view (top view) of the semiconductor device 101. Figure 14A is a cross-sectional view of the semiconductor device 101 along the line B-B'. Figure 14A is a plan view of the semiconductor device 101 with the sealing material 360 removed. Figure 15A is a plan view of the semiconductor device 101 with the sixth conductor plate 114 removed. This is a plan view showing the arrangement of bonding materials of the semiconductor element 700 according to Embodiment 6 of the present invention. Figure 16A is a cross-sectional view of the semiconductor element 700 along the line C-C'. This is a circuit diagram of the power converter according to Embodiment 7 of the present invention. Figure 17 is an external perspective view of the power converter 800. Figure 18 is a cross-sectional perspective view of the power converter 800 along the line XV-X'V'.

[0013] Embodiments of the present invention will be described below with reference to the drawings. In each drawing, identical components are denoted by the same reference numerals, and detailed descriptions of overlapping parts are omitted.

[0014] A power semiconductor module according to Embodiment 1 of the present invention will be described with reference to Figures 1 to 8B.

[0015] Figure 1 is a plan view (top view) of the electrical circuit body 400 according to this embodiment. The electrical circuit body 400 comprises a plurality of semiconductor devices (power semiconductor modules) 300 and a cooling member 340. In the example shown in Figure 1, three semiconductor devices 300 are provided in parallel in the electrical circuit body 400. The semiconductor device 300 contains semiconductor elements 155, 156, 157, and 158 (see Figure 5), which will be described later, sealed with a sealing material 360. Terminals connected to each semiconductor element 155, 156, 157, and 158 are led out from the sealing material 360 on the side of the semiconductor device 300.

[0016] These terminals are power terminals through which large currents flow, such as the positive terminal 315B, the negative terminal 319B, and the AC terminal 320B. In addition, terminals leading out from the sealing material 360 on the side of the semiconductor device 300 are provided, such as the gate signal terminal 325G and the source signal terminal 325S, which are used to control the semiconductor device 300.

[0017] An electrical circuit 400, comprising three semiconductor devices 300 arranged in parallel, functions as a power converter that converts DC current and AC current through the switching operation of each semiconductor element 155, 156, 157, and 158. The number of semiconductor devices 300 in the electrical circuit 400 is not limited to three, but can be arbitrarily set to suit various configurations of the electrical circuit 400.

[0018] The cooling member 340 is positioned opposite the heat dissipation surface of each semiconductor device 300 and cools the heat generated by the switching operation of the semiconductor elements 155, 156, 157, and 158. Specifically, the cooling member 340 has a flow path through which a coolant flows, and the coolant flowing through the flow path cools the heat generated by the semiconductor device 300. The coolant can be water or an antifreeze solution made by mixing ethylene glycol with water. The cooling member 340 is preferably made of a copper-based material with high thermal conductivity, or even better, an aluminum-based material with high thermal conductivity and light weight. These materials are used to manufacture the cooling member 340 by extrusion molding, forging, brazing, etc.

[0019] Figure 2 is a cross-sectional view of the electrical circuit body 400 shown in Figure 1 along the line X-X', and Figure 3 is a cross-sectional perspective view of the electrical circuit body 400 shown in Figure 1 along the line Y-Y'. The electrical circuit body 400 is equipped with a pressurizing mechanism that pressurizes the semiconductor device 300 by sandwiching it from both sides with cooling members 340 and 350 provided on both sides of the semiconductor device 300. The pressurizing mechanism is not shown in the figure, but for example, it is a mechanism that pressurizes the semiconductor device 300 by connecting the cooling members 340 and 350 on both sides with screws or the like.

[0020] As shown in Figure 2, the electrical circuit body 400 includes a semiconductor element 155 as a first semiconductor element that forms the upper arm circuit. The drain side of the first semiconductor element 155 is joined to the first conductor plate 431. Solder or sintered metal may be used for this joining. A third conductor plate 433 is joined to the source side of the first semiconductor element 155. The third conductor plate 433 is provided with a base electrode to connect to the surface electrode of the first semiconductor element 155 while maintaining an insulating distance.

[0021] Furthermore, materials such as Si, SiC, GaN, GaO, and C can be used as the semiconductor chip material for semiconductor elements 155, 156, 157, and 158. Semiconductor elements 155, 156, 157, and 158 are, for example, power semiconductor elements such as IGBTs (Insulated Gate Bipolar Transistors) and MOSFETs (Metal Oxide Semiconductor Field-Effect Transistors). Conductor plates 431, 432, 433, and 434 are not particularly limited as long as they are made of materials with high electrical and thermal conductivity, but it is desirable to use metallic materials such as copper-based or aluminum-based materials, or composite materials such as diamond, carbon, or ceramics with high thermal conductivity. These may be used alone, but plating with Ni or Ag may be applied to improve bonding with solder or sintered metal.

[0022] As shown in Figures 2 and 3, the conductive plates 431, 432, 433, and 434 not only conduct electric current but also act as heat transfer members, transferring heat generated by the semiconductor elements 155, 156, 157, and 158 to the cooling members 340 and 350. Since the conductive plates 431, 432, 433, and 434 and the cooling members 340 and 350 have different potentials, it is desirable to use insulating sheets 440 and 441 between them.

[0023] The semiconductor elements 155, 156, 157, 158, the conductive plates 431, 432, 433, 434, and the insulating sheets 440, 441 are sealed with a sealing material 360 by transfer molding to constitute the semiconductor device 300. To reduce the contact thermal resistance between the semiconductor device 300 and the cooling members 340, 350, a heat conductive member 453 is placed between the semiconductor device 300 and the cooling members 340, 350.

[0024] The resin insulating layers 442 and 443 of the insulating sheets 440 and 441 are not particularly limited as long as they have adhesive properties with respect to the cooling members 340 and 350, but an epoxy resin-based resin insulating layer with dispersed powdered inorganic filler is preferable. This is because it offers a good balance between adhesion and heat dissipation. The insulating sheets 440 and 441 may consist of the resin insulating layer alone, but it is preferable to provide a metal foil 444 on the side that comes into contact with the heat conductive member 453. In the transfer mold molding process, when the insulating sheets 440 and 441 are mounted on the mold, a release sheet or metal foil 444 is provided on the contact surface of the insulating sheets 440 and 441 with the mold to prevent adhesion to the mold.

[0025] While release sheets require a peeling step after transfer molding due to their poor thermal conductivity, in the case of metal foil 444, by selecting a metal with high thermal conductivity such as copper or aluminum, it can be used without peeling after transfer molding. By performing transfer molding including insulating sheets 440 and 441, the edges of the insulating sheets 440 and 441 are covered with the sealing material 360, which improves reliability.

[0026] The heat conductive member 453 can be made of a material that is fluid at room temperature or high temperature, such as grease, gel grease, or phase change sheet. However, to ensure workability and long-term reliability, a curable heat conductive material that is fluid before curing and loses its fluidity after curing is preferable. Curable heat conductive members have the advantage of low viscosity and excellent workability when applied, and can improve mechanical properties after curing. Curing can be achieved using thermosetting, moisture curing, or UV curing, but thermosetting is preferable for curing to deep layers.

[0027] The heat conduction member 453 is not particularly limited as long as it is made of a material with high thermal conductivity, but it is preferable to use a high thermal conductivity material such as metal, ceramics, or carbon-based material in combination with a resin material. This is because the resin material fills the gaps between the high thermal conductivity materials, between the high thermal conductivity materials and the cooling members 340, 350, and between the high thermal conductivity materials and the insulating sheets 440, 441, thereby reducing contact thermal resistance. The resin material is not particularly limited. The most desirable resin is a silicone resin that shows little change in elastic modulus from around -40°C to around 200°C. In addition, insulating materials are preferred for the heat conduction member. This is to prevent a decrease in insulation due to the adhesion of conductive material near the terminals.

[0028] The thermal conductivity of the heat conduction member 453 is approximately 5 to 10 W / (m·K). The method for measuring the thermal conductivity is not particularly limited. For example, the density, specific gravity, and thermal diffusivity of the heat conduction member 453 can be measured, and the thermal conductivity can be calculated by multiplying density by specific gravity by thermal diffusivity.

[0029] Figure 4 is a plan view (top view) of the semiconductor device (power semiconductor module) 300 of Figure 1. Figure 5 is a semi-transparent plan view of the semiconductor device 300 of Figure 4. Figure 6 is an equivalent circuit diagram of the semiconductor device 300 of Figure 4. As shown in Figures 4, 5, and 6, the positive terminal 315B outputs from the drain side of the upper arm circuit. The gate signal terminal 325G of the upper arm circuit outputs from the gates of semiconductor elements 155 and 156 of the upper arm circuit. The negative terminal 319B outputs from the source side of the lower arm circuit.

[0030] The gate signal terminal 325G of the lower arm circuit is output from the gates of semiconductor elements 157 and 158 of the lower arm circuit. The AC side terminal 320B is output from the connection between the source side of the upper arm circuit and the drain side of the lower arm circuit. The source signal terminal 325S of the upper arm circuit is output from the source side of the upper arm circuit. The source signal terminal 325S of the lower arm circuit is output from the source side of the lower arm circuit.

[0031] First conductor plates 431 and third conductor plate 433 are positioned above and below the semiconductor elements 155 and 156 of the upper arm circuit, respectively. Second conductor plate 432 and fourth conductor plate 434 are positioned above and below the semiconductor elements 157 and 158 of the lower arm circuit, respectively. The source electrode pads (first electrode regions) 370 of the semiconductor elements 155, 156, 157, and 158, which will be described later using Figure 7A, are connected to the source signal terminal 325S by bonding wires 361. Similarly, the gate electrode pads 371 of the semiconductor elements 155, 156, 157, and 158 are connected to the gate signal terminal 325G by bonding wires 361.

[0032] The semiconductor device 300 in this embodiment has a 2-in-1 structure in which two arm circuits, an upper arm circuit and a lower arm circuit, are integrated into a single module. Alternatively, a structure in which multiple combinations of upper arm circuits and lower arm circuits are integrated into a single module may be used. In this case, the number of output terminals from the semiconductor device 300 can be reduced, thereby miniaturizing the device.

[0033] Figure 7A is a plan view showing the arrangement of the source-side bonding material 160 of the semiconductor element 155 in Figure 5. The first electrode regions 370 and 372, which are source electrode pads, and the second electrode region 373, which is a source electrode and has a larger area than the first electrode regions 370 and 372, are each bonded by the source-side bonding material 160. A base (not shown) for the third conductor plate 433, which is a source conductor, is provided on the second electrode region 373.

[0034] Figure 7B is a cross-sectional view showing the arrangement of the source-side bonding material 160 of the semiconductor element 155 in Figure 5, and is a cross-sectional view taken along the line A-A' in Figure 7A. The source-side bonding material 160 connects the first electrode region 370, which is the source electrode pad, and the second electrode region 373, which is the source electrode. In addition, the base of the third conductor plate 433, which is the source conductor, and the source-side bonding material 160 on the second electrode region 373 are bonded together.

[0035] By connecting the first electrode regions 370 and 372, which are source electrode pads, and the second electrode region 373, which is a source electrode, with the source-side bonding material 160, heat generated from the active region can be dissipated through the third conductor plate 433, which is a source conductor. As a result, localized temperature rises within the semiconductor chip are eliminated, and the temperature rise of the gate electrode pad 371, which is a bonding wire connection portion, can be suppressed.

[0036] Furthermore, the thickness of the source-side bonding material 160 should be set such that t1 ≥ t2 holds, where t1 is the thickness of the bonding material on the first electrode regions 370 and 372, and t2 is the thickness of the bonding material on the second electrode region 373. By setting the thickness of the source-side bonding material 160 to t1 ≥ t2, heat generated from the active region can be dissipated not only from the base surface portion of the third conductor plate 433 but also from the base side surface, via the third conductor plate 433, which is the source conductor.

[0037] An insulating film is placed between the first electrode regions 370, 372 and the second electrode region 373. The adhesion between the insulating film and the source-side bonding material 160 is weak, and the adhesion between the insulating film and the solder will not improve unless some kind of pretreatment is performed on the insulating film. Therefore, as shown in Figure 7B, by making the thickness of the bonding material on the first electrode regions 370, 372 thicker than the thickness of the bonding material on the second electrode region 373 (t1 ≥ t2), the bonding material is joined to the base side of the third conductor plate 433, which is the source conductor, thereby reinforcing the weak adhesion between the insulating film and the source-side bonding material 160.

[0038] Furthermore, methods to improve the connectivity between the insulating film between the first electrode regions 370, 372 and the second electrode region 373 and the source-side bonding material 160 include plating the insulating film, plasma treatment of the insulating film, and application of adhesive to the insulating film. In the method of plating the insulating film, the surface of the insulating film is partially modified by irradiating it with laser light, and a catalyst is supported on the modified portion to form partial plating. Palladium can be used as a catalyst, for example. For plating, Au plating, Sn plating, Ni plating, etc., can be used.

[0039] Applying oxygen plasma treatment to the insulating film improves its wettability and adhesion to water, significantly enhancing the adhesion between the solder and the insulating film. Alternatively, an adhesive can be applied to the insulating film, dried, and then a bonding material can be placed on top. Heating is then used to bond the adhesive and the bonding material. Thermosetting resins such as epoxy resin and acrylic resin can be used as the adhesive. These methods can further improve the adhesion between the insulating film and the bonding material.

[0040] Figures 8A and 8B are cross-sectional views showing the method for forming the source-side bonding material 160 in Figure 7B. In the example of Figure 8A, the source-side bonding material 160 is formed by overlapping bonding material 160A, which has a length from within the first electrode regions 370, 372 to within the second electrode region 373, with bonding material 160B and 160C, which have a length within the first electrode regions 370, 372. In the example of Figure 8B, the source-side bonding material 160 is formed by bonding material 160D and 160E, which have a length within the first electrode regions 370, 372, with bonding material 160F, which has a length within the second electrode region 373, on the semiconductor element 155. In both cases, the thickness of the source-side bonding material 160 satisfies t1 ≥ t2.

[0041] As described above, the semiconductor device of this embodiment has gate electrodes (gate electrode pads 371) and source electrodes (source electrode pads 370, 372, source electrode 373) on the main surfaces of semiconductor elements 155, 156, 157, and 158. Gate wiring (bonding wires 361) is connected to the gate electrodes by wire bonding, and a source conductor (third conductor plate 433) is bonded to the source electrodes via a conductive bonding material (source-side bonding material 160). In a plan view from the thickness direction of the semiconductor element, the source electrode has a first electrode region (source electrode pads 370, 372) adjacent to the gate electrode along one side of the semiconductor element where the gate wiring intersects, and a second electrode region (source electrode 373) adjacent to the gate electrode and the first electrode region, and having a larger area than the first electrode region. The bonding material is in contact with the first electrode region and the second electrode region, and the contact region between the bonding material and the source conductor is formed so as not to overlap with the first electrode region but to overlap with the second electrode region in a plan view.

[0042] Also, on the main surface side of the semiconductor element, there are a first heat conduction member (heat conduction member 453) disposed on the source conductor, and a first cooling member (source side cooling member 340) that is disposed facing the semiconductor element with the source conductor and the first heat conduction member interposed therebetween and cools the heat generated by the semiconductor element. On the surface of the semiconductor element opposite to the main surface, there are a drain electrode (not shown), a drain conductor (first conductor plate 431) joined to the drain electrode via a conductive bonding material (drain side bonding material 161), a second heat conduction member (heat conduction member 453) disposed on the drain conductor, and a second cooling member (drain side cooling member 350) that is disposed facing the semiconductor element with the drain conductor and the second heat conduction member interposed therebetween and cools the heat generated by the semiconductor element.

[0043] Thus, in a double-sided cooled power semiconductor module to which a semiconductor element in which an active region is formed so as to extend also beside a gate electrode pad and a source electrode pad is disposed in the extended active region, disconnection of the gate electrode wire can be prevented, and a highly reliable semiconductor device can be provided.

[0044] Referring to FIGS. 9 and 10, a power semiconductor module according to Embodiment 2 of the present invention will be described. This embodiment is a modification of Embodiment 1.

[0045] In Embodiment 1 (FIG. 5), each source electrode pad (first electrode region) 370 of the semiconductor elements 155, 156, 157, 158 is connected to the source signal terminal 325S by the bonding wire 361, whereas in this embodiment (FIG. 10), each source electrode pad (first electrode region) 370 is different in that it is connected to the source signal terminal 325S by a source terminal 433T that is a part of the third conductor plate 433 and a source terminal 434T that is a part of the fourth conductor plate 434. Other configurations are the same as those in Embodiment 1 (FIG. 5).

[0046] FIG. 9 is a plan view (top view) of the semiconductor device 300 of the present embodiment. FIG. 10 is a semi-transmissive plan view of the semiconductor device 300 of FIG. 9. As shown in FIGS. 9 and 10, the positive electrode side terminal 315B outputs from the drain side of the upper arm circuit. The gate signal terminal 325G of the upper arm circuit outputs from the gates of the semiconductor elements 155 and 156 of the upper arm circuit. The negative electrode side terminal 319B outputs from the source side of the lower arm circuit.

[0047] The gate signal terminal 325G of the lower arm circuit outputs from the gates of the semiconductor elements 157 and 158 of the lower arm circuit. The AC side terminal 320B outputs from the connection portion between the source side of the upper arm circuit and the drain side of the lower arm circuit. The source signal terminal 325S of the upper arm circuit outputs from the source side of the upper arm circuit. The source signal terminal 325S of the lower arm circuit outputs from the source side of the lower arm circuit.

[0048] The first conductor plate 431 and the third conductor plate 433 are respectively arranged above and below the semiconductor elements 155 and 156 of the upper arm circuit, and the source terminal 433T provided on the third conductor plate 433 and the source signal terminal 325S are connected by a bonding material (not shown). Each source electrode pad (first electrode region) 370 of the semiconductor elements 155 and 156 is connected to the source signal terminal 325S by the source terminal 433T.

[0049] Similarly, the second conductor plate 432 and the fourth conductor plate 434 are respectively arranged above and below the semiconductor elements 157 and 158 of the lower arm circuit, and the source terminal 434T provided on the fourth conductor plate 434 and the source signal terminal 325S are connected by a bonding material (not shown). Each source electrode pad (first electrode region) 370 of the semiconductor elements 157 and 158 is connected to the source signal terminal 325S by the source terminal 434T.

[0050] Referring to FIG. 11, the power semiconductor module according to Embodiment 3 of the present invention will be described. This embodiment is a modification of Embodiment 1 (FIG. 5).

[0051] In Example 1 (Figure 5), two semiconductor elements 155 and 156 are mounted on the upper arm circuit and two semiconductor elements 157 and 158 are mounted on the lower arm circuit, whereas in this Example (Figure 11), three semiconductor elements are mounted on both the upper arm circuit and the lower arm circuit. The other configurations are the same as in Example 1 (Figure 5).

[0052] Figure 11 is a semi-transparent plan view of the semiconductor device 300 of this embodiment. As shown in Figure 11, the positive terminal 315B outputs from the drain side of the upper arm circuit. The gate signal terminal 325G of the upper arm circuit outputs from the gates of the three semiconductor elements 170, 171, and 172 of the upper arm circuit. The negative terminal 319B outputs from the source side of the lower arm circuit. The gate signal terminal 325G of the lower arm circuit outputs from the gates of the three semiconductor elements 173, 174, and 175 of the lower arm circuit. The AC terminal 320B outputs from the drain side of the lower arm circuit.

[0053] The first conductor plate 431 and the third conductor plate 433 are positioned above and below the semiconductor elements 170, 171, and 172 of the upper arm circuit, respectively. The second conductor plate 432 and the fourth conductor plate 434 are positioned above and below the semiconductor elements 173, 174, and 175 of the lower arm circuit, respectively.

[0054] Referring to Figure 12, a power semiconductor module according to Embodiment 4 of the present invention will be described. This embodiment is a modification of Embodiment 2 (Figure 10).

[0055] In Example 2 (Figure 10), two semiconductor elements 155 and 156 are mounted on the upper arm circuit and two semiconductor elements 157 and 158 are mounted on the lower arm circuit, whereas in this Example (Figure 12), three semiconductor elements are mounted on both the upper arm circuit and the lower arm circuit. The other configurations are the same as in Example 2 (Figure 10).

[0056] Figure 12 is a semi-transparent plan view of the semiconductor device 300 of this embodiment. As shown in Figure 12, the positive terminal 315B outputs from the drain side of the upper arm circuit. The gate signal terminal 325G of the upper arm circuit outputs from the gates of the three semiconductor elements 170, 171, and 172 of the upper arm circuit. The negative terminal 319B outputs from the source side of the lower arm circuit. The gate signal terminal 325G of the lower arm circuit outputs from the gates of the three semiconductor elements 173, 174, and 175 of the lower arm circuit. The AC terminal 320B outputs from the drain side of the lower arm circuit.

[0057] A first conductor plate 431 and a third conductor plate 433 are arranged above and below the semiconductor elements 170, 171, and 172 of the upper arm circuit, respectively. A source terminal 433T and a source signal terminal 325S provided on the third conductor plate 433 are connected by a bonding material (not shown). Each source electrode pad (first electrode region) 370 of the semiconductor elements 170, 171, and 172 is connected to the source signal terminal 325S by the source terminal 433T.

[0058] Similarly, a second conductor plate 432 and a fourth conductor plate 434 are arranged above and below the semiconductor elements 173, 174, and 175 of the lower arm circuit, respectively, and a source terminal 434T and a source signal terminal 325S provided on the fourth conductor plate 434 are connected by a bonding material (not shown). The source electrode pads (first electrode regions) 370 of each semiconductor element 173, 174, and 175 are connected to the source signal terminal 325S by the source terminal 434T.

[0059] Referring to Figures 13 to 15B, a power semiconductor module according to Embodiment 5 of the present invention will be described. This embodiment is a modification of Embodiment 1 (Figure 2) concerning the mounting method of a power semiconductor module.

[0060] Figure 13 is a cross-sectional view of the electrical circuit body 100 of this embodiment. The electrical circuit body 100 has a configuration that is substantially symmetrical above and below Figure 13, with the printed circuit board 108 in between. The semiconductor device (power semiconductor module) 101 is placed in an opening formed in the printed circuit board 108 and is electrically connected to the circuit wiring formed in the printed circuit board 108. The lower surface of the semiconductor device 101 is aligned with a predetermined reference plane. By aligning the lower surface of the semiconductor device 101 with a unified reference plane, it becomes possible to arrange multiple semiconductor devices 101 with respect to one heat dissipation member 200. In this embodiment, as shown in Figure 13, four semiconductor devices 101 are arranged in the width direction of the electrical circuit body 100, and one heat dissipation member 200 is placed on each of their upper and lower sides.

[0061] Plate-shaped insulating members 103 are bonded to both the upper and lower surfaces of the semiconductor device 101 via an adhesive layer 102. For example, an alumina plate, an alumina-zirconia plate, or a silicon nitride plate can be used for the insulating member 103. The thermal conductivity of the insulating member 103 is preferably 0.5 (W / mK) or higher. The insulating member 103 is further connected to the heat dissipation member 200 via an adhesive layer 102. For example, a silicone adhesive or epoxy adhesive with fillers such as zinc oxide or alumina powder can be used for the adhesive layer 102. A metallic bonding material such as solder or brazing material may also be used for the adhesive layer 102. By interposing the adhesive layer 102 in this way, good heat conduction can be maintained between the semiconductor device 101 and the insulating member 103, and between the insulating member 103 and the heat dissipation member 200.

[0062] The heat dissipation member 200 is fixed to the semiconductor device 101 on one side via two adhesive layers 102 and an insulating member 103. On the side of the heat dissipation member 200 opposite to the side fixed to the semiconductor device 101, a plurality of heat dissipation pins 203 are formed as a heat dissipation section. In this embodiment, pin-shaped heat dissipation pins 203 are used for the heat dissipation section, but the heat dissipation section can be made of any shape that can increase the surface area of ​​the heat dissipation member 200 in contact with the refrigerant and enhance the heat dissipation effect, such as fins or plates, and is not limited to pin shapes. Furthermore, the heat dissipation member 200 can be made of a metal material with high thermal conductivity, such as copper or aluminum. The thermal conductivity of the heat dissipation member 200 is preferably 200 (W / mK) or higher.

[0063] The heat dissipation member 200 is inserted into an opening formed in the frame 109, with the inner circumferential surface of the opening in the frame 109 facing the outer circumferential surface of the base portion of the heat dissipation member 200. The area around the opening on one side of the frame 109 is positioned to face a flange formed on the outer circumferential surface of the heat dissipation member 200 on the semiconductor device 101 side. It is desirable that the frame 109 be made of a highly rigid metal material such as stainless steel or copper.

[0064] A sealing member 106 is filled between the heat dissipation member 200 and the frame 109. It is desirable that the sealing member 106 has electrical insulating properties and elasticity. For example, a resin material can be used as the sealing member 106.

[0065] The electrical circuit body 100 is further covered on both the upper and lower sides in Figure 13 by covers 107. As described above, the covers 107 are fixed to the frame 109 at multiple points, for example, by screws. The portion of the cover 107 facing the heat dissipation member 200 has an elastic biasing portion 110 that protrudes toward the heat dissipation member 200. The elastic biasing portion 110 is biased toward the heat dissipation member 200 so as to be in close contact with the tip portion of the heat dissipation pin 203 via the elastic member 104. By interposing the elastic member 104, even if the amount of deformation of the elastic biasing portion 110 is insufficient, the gap between the heat dissipation pin 203 and the elastic biasing portion 110 is compensated for, maintaining close contact and improving cooling performance. Preferably, the elastic member 104 is made of an insulating resin material.

[0066] It is preferable that the cover 107, like the frame 109, be made of a highly rigid metal material such as stainless steel or copper. By using highly rigid materials for the cover 107 and frame 109, plastic deformation of the cover 107 and frame 109 due to the biasing force on the elastic biasing portion 110 can be suppressed, and the tight contact between the tip of the heat dissipation pin 203 and the elastic biasing portion 110 can be maintained.

[0067] The space formed by the heat dissipation member 200, the cover 107, and the frame 109 becomes a flow path 302 for the refrigerant. The heat dissipation pins 203 are arranged in the flow path 302, and the refrigerant flows between the heat dissipation pins 203. The heat generated in the semiconductor device 101 is transferred to the heat dissipation member 200 and released from the heat dissipation pins 203 into the refrigerant in the flow path 302. In this way, the semiconductor device 101 is cooled from both sides by the refrigerant flowing through the flow path 302.

[0068] In this case, if different metal components are used between the heat dissipation member 200 and the cover 107 and frame 109, and the natural potentials of these metals in the refrigerant are different, galvanic corrosion may occur when the heat dissipation member 200 and the cover 107 or frame 109 come into contact in the flow path 302, causing the metal with the lower potential to corrode due to battery action. In this embodiment, by interposing an elastic member 104 between the heat dissipation pin 203 and the elastic biasing part 110, direct contact between the heat dissipation pin 203 and the elastic biasing part 110 can be prevented, thereby suppressing the occurrence of galvanic corrosion.

[0069] Figure 14A is a plan view (top view) of the semiconductor device 101 shown in Figure 13. Figure 14B is a cross-sectional view of the semiconductor device 101 shown in Figure 14A along the line B-B'. Figure 15A is a plan view of the semiconductor device 101 shown in Figure 14A with the sealing material 360 removed. Figure 15B is a plan view of the semiconductor device 101 shown in Figure 15A with the sixth conductor plate 114 removed.

[0070] The semiconductor device 101 has a semiconductor element 124 which is a SiC element. The semiconductor element 124 is placed between the fifth conductor plate 113 and the sixth conductor plate 114.

[0071] The sixth conductor plate 114 is provided with a base electrode to connect to the surface electrode of the semiconductor element 124 while maintaining an insulating distance. The first terminal 111, the second terminal 112, and the control signal terminal 115 protrude from the fifth conductor plate 113, and the switching control of the semiconductor device 101 is performed by electrically connecting each of these protruding portions to the printed circuit board 108 shown in Figure 13.

[0072] As shown in Figure 14B, in this embodiment as well, similar to Embodiment 1, the thickness of the bonding material on the first electrode region of the source-side bonding material 125 is set to be equal to or greater than the thickness of the bonding material on the second electrode region. By making the thickness of the bonding material on the first electrode region equal to or greater than the thickness of the bonding material on the second electrode region, heat generated not only from the base plane portion of the sixth conductor plate 114 but also from the base side surface can be dissipated through the sixth conductor plate 114, which is the source conductor.

[0073] A power semiconductor module according to Embodiment 6 of the present invention will be described with reference to Figures 16A and 16B. This embodiment is a modification of Embodiment 1 (Figures 7A and 7B).

[0074] Figure 16A is a plan view showing the arrangement of bonding materials for the semiconductor element 700 in this embodiment. The first electrode region 701, which is a source electrode pad, and the second electrode region 703, which is a source electrode, are each bonded by a source-side bonding material 704. A third conductor plate 433 (not shown), which is a source conductor, is provided on the second electrode region 703.

[0075] Figure 16B is a cross-sectional view of the semiconductor element 700 in Figure 16A along the line C-C'. The first electrode region 701, which is the source electrode pad, and the second electrode region 703, which is the source electrode, are connected by the source-side bonding material 704. The third conductor plate 433 (not shown), which is the source conductor, and the source-side bonding material 704 on the second electrode region 703 are bonded together. By connecting the first electrode region 701, which is the source electrode pad, and the second electrode region 703, which is the source electrode, with the bonding material, heat generated from the active region can be dissipated through the source-side bonding material 704 on the second electrode region 703.

[0076] Therefore, localized temperature increases within the semiconductor chip are eliminated, and the temperature rise of the bonding wire connection portion (gate electrode pad 702) can be suppressed. In this embodiment as well, the thickness of the source-side bonding material 704 is set such that t1 ≥ t2 holds, where t1 is the thickness of the bonding material on the first electrode region 701 and t2 is the thickness of the bonding material on the second electrode region 703. By setting the thickness of the source-side bonding material 704 to t1 ≥ t2, heat generated not only from the base plane portion of the third conductor plate 433 (not shown) but also from the base side surface can be dissipated through the third conductor plate 433, which is the source conductor.

[0077] Similar to Example 1 (Figure 7B), an insulating film is placed between the first electrode region 701 and the second electrode region 703. The adhesion between the insulating film and the source-side bonding material 704 is weak, and the adhesion between the insulating film and the solder will not improve unless some kind of pretreatment is performed on the insulating film. Therefore, as shown in Figure 16B, by making the thickness of the bonding material on the first electrode region 701 thicker than the thickness of the bonding material on the second electrode region 703 (t1 ≥ t2), the bonding material is joined to the base side of the third conductor plate 433, which is the source conductor, thereby reinforcing the weak adhesion between the insulating film and the source-side bonding material 704.

[0078] Furthermore, similar to Example 1 (Figure 7B), methods for improving the connectivity between the insulating film between the first electrode region 701 and the second electrode region 703 and the source-side bonding material 704 include plating the insulating film, plasma treatment of the insulating film, and application of adhesive to the insulating film.

[0079] According to each embodiment of the present invention described above, by connecting the first electrode region (370, 372, 701), which is a source electrode pad, and the second electrode region (373, 703), which is a source electrode, with a source-side bonding material (160, 704), heat generated from the active region can be dissipated through the source conductor (433, 434). As a result, localized temperature rises within the semiconductor chip are eliminated, and the temperature rise of the gate electrode pad (371, 702), which is a bonding wire connection, can be suppressed. This suppresses cracks in the bonding wire connection and provides a highly reliable semiconductor device (power semiconductor module).

[0080] A power conversion device according to Embodiment 7 of the present invention will be described with reference to Figures 17 to 19.

[0081] Figure 17 is a circuit diagram of a power converter 800 using a semiconductor device (power semiconductor module) according to the present invention. The power converter 800 mainly comprises inverter circuit sections 840 and 842, an auxiliary inverter circuit section 843, and a capacitor module 500. The inverter circuit sections 840 and 842 each contain multiple power semiconductor modules 300, and by connecting them, a three-phase bridge circuit is formed. When the current capacity is large, the current capacity can be increased by further connecting power semiconductor modules 300 in parallel and performing these parallel connections corresponding to each phase of the three-phase inverter circuit. In addition, the current capacity can be increased by connecting the semiconductor elements 855, 856, 857, and 858 built into the power semiconductor module 300 in parallel.

[0082] Inverter circuit section 840 and inverter circuit section 842 have the same basic circuit configuration, and their control methods and operations are also basically the same. Since the general operation of the inverter circuit section 840 and others is well known, a detailed explanation will be omitted here.

[0083] The upper arm circuit is equipped with semiconductor elements 855 and 856 for the upper arm as switching semiconductor elements, and the lower arm circuit is equipped with semiconductor elements 857 and 858 for the lower arm as switching semiconductor elements. The semiconductor elements 855, 856, 857, and 858 receive a drive signal output from one or the other of the two driver circuits that constitute the driver circuit 874 and perform switching operations to convert the DC power supplied from the battery 836 into three-phase AC power.

[0084] The positive terminal 315B and negative terminal 319B of each upper and lower arm series circuit are connected to the DC terminals for capacitor connection of the capacitor module 500, respectively. AC power is generated at the connection points of the upper and lower arm circuits, and the connection points of the upper and lower arm circuits of each upper and lower arm series circuit are connected to the AC terminals 320B of each power semiconductor module 300. The AC terminals 320B of each phase of each power semiconductor module 300 are connected to the AC output terminals of the power converter 800, and the generated AC power is supplied to the stator windings of the motor generator 192 or 194.

[0085] The control circuit 872 generates timing signals to control the switching timing of the semiconductor elements 855 and 856 for the upper arm and 857 and 858 for the lower arm, based on input information from the vehicle's control device and sensors (e.g., current sensor 880). The driver circuit 874 generates drive signals to switch the semiconductor elements 855 and 856 for the upper arm and 857 and 858 for the lower arm, based on the timing signals output from the control circuit 872. Reference numerals 21, 181, and 188 indicate connectors.

[0086] The upper and lower arm series circuit includes a temperature sensor (not shown), and temperature information from the upper and lower arm series circuit is input to the microcontroller. The microcontroller is also input voltage information from the DC positive terminal side of the upper and lower arm series circuit. Based on this information, the microcontroller performs over-temperature detection and over-voltage detection. If over-temperature or over-voltage is detected, the microcontroller stops the switching operation of all semiconductor elements 855, 156 for the upper arm and semiconductor elements 857, 858 for the lower arm, protecting the upper and lower arm series circuit from over-temperature or over-voltage.

[0087] Figure 18 is an external perspective view showing an example of the power converter 800 shown in Figure 17, and Figure 19 is a cross-sectional perspective view of the power converter 800 shown in Figure 18 along the line XV-X'V'.

[0088] The power converter 800 is comprised of a lower case 811 and an upper case 810, and has a housing 812 that is formed in a substantially rectangular parallelepiped shape. Inside the housing 812 are an electrical circuit 400, a capacitor module 500, and the like. The electrical circuit 400 has a cooling channel, and a cooling water inlet pipe 813 and a cooling water outlet pipe 814 that communicate with the cooling channel protrude from one side of the housing 812.

[0089] The lower case 811 has an opening on its upper side, and the upper case 810 is attached to the lower case 811, closing the opening of the lower case 811. The upper case 810 and the lower case 811 are made of an aluminum alloy or the like, and are sealed and fixed to the outside. The upper case 810 and the lower case 811 may also be constructed as a single unit. By making the housing 812 a simple rectangular parallelepiped shape, it becomes easy to attach it to vehicles and the like, and also easier to manufacture.

[0090] A connector 817 is attached to one longitudinal side of the housing 812, and an AC terminal 818 is connected to this connector 817. In addition, a connector 21 is provided on the side from which the cooling water inlet pipe 813 and the cooling water outlet pipe 814 are led out.

[0091] An electrical circuit body 400 is housed inside the casing 812. A control circuit 872 and a driver circuit 874 are located above the electrical circuit body 400, and a capacitor module 500 is housed on the DC terminal side of the electrical circuit body 400. By positioning the capacitor module 500 at the same height as the electrical circuit body 400, the power converter 800 can be made thinner, improving the flexibility of installation in vehicles. The DC terminals of the power semiconductor module 300, the positive terminal 315B and the negative terminal 319B, are connected to the positive and negative terminals 362A and 362B of the capacitor module 500, respectively.

[0092] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are included. For example, the embodiments described above are described in detail to make the present invention easier to understand, and are not necessarily limited to those having all the configurations described. Furthermore, it is possible to replace parts of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add configurations from other embodiments to the configuration of one embodiment. In addition, it is possible to add, delete, or replace parts of the configuration of each embodiment with other configurations.

[0093] 21, 138, 181, 188, 817... Connectors, 100, 400... Electrical circuit bodies, 101, 300... Semiconductor devices (power semiconductor modules), 102... Adhesive layers, 103... Insulating members, 104... Elastic members, 106... Seal members, 107... Covers, 108... Printed circuit boards, 109... Frames, 110... Elastic biasing parts, 111... First terminals, 112... Second terminals, 113... Fifth conductor plate, 114... Sixth conductor plate, 115... Control signal terminals, 124... (11th) semiconductor elements, 12 5...Source-side bonding material, 126...Drain-side bonding material, 155...(1st) semiconductor element, 156...(2nd) semiconductor element, 157...(3rd) semiconductor element, 158...(4th) semiconductor element, 160, 162, 164, 166, 704...Source-side bonding material, 160A, 160B, 160C, 160D, 160E, 160F...Bonding material, 161, 165...Drain-side bonding material, 167...Intermediate terminal bonding material, 170...(5th) semiconductor element, 171...(6th) semiconductor element, 172...(7th) Semiconductor element, 173... (8th) Semiconductor element, 174... (9th) Semiconductor element, 175... (10th) Semiconductor element, 192, 194... Motor generator, 200... Heat dissipation member, 203... Heat dissipation pin, 302... Flow channel, 315B... Positive terminal, 319B... Negative terminal, 320B... AC terminal, 325G... Gate signal terminal, 325S... Source signal terminal, 340... (Source side) Cooling member, 350... (Drain side) Cooling member, 360... Encapsulation material, 361... Bonding wire, 37 0, 372, 701... Source electrode pad (first electrode region), 371, 702... Gate electrode pad, 373, 703... Source electrode (second electrode region), 431... First conductor plate (upper arm circuit drain side), 432... Second conductor plate (lower arm circuit drain side), 433... Third conductor plate (upper arm circuit source side), 433T... Source terminal (upper arm circuit source side), 434... Fourth conductor plate (lower arm circuit source side), 434T... Source terminal (lower arm circuit source side), 440,441...Insulating sheet, 442...First resin insulating layer, 443...Second resin insulating layer, 444...Metal foil, 453...Heat conductive material, 500...Capacitor module, 700...(12th) semiconductor element, 704A...Source electrode pad bonding material, 704B...Source electrode bonding material, 800...Power converter, 810...Upper case, 811...Lower case, 812...Housing, 813...Cooling water inlet pipe, 814...Cooling water outlet pipe, 818...AC terminal, 836...Battery, 840, 842, 843...Inverter circuit section, 855, 856, 857, 858...Semiconductor elements, 872...Control circuit, 874...Driver circuit, 880...Current sensor.

Claims

1. A semiconductor device having a gate electrode and a source electrode on the main surface of a semiconductor element, wherein a gate wiring is connected to the gate electrode by wire bonding, and a source conductor is bonded to the source electrode via a conductive bonding material, wherein the source electrode has, in a plan view from the thickness direction of the semiconductor element, a first electrode region adjacent to the gate electrode along one side of the semiconductor element where the gate wiring intersects, and a second electrode region adjacent to the gate electrode and the first electrode region, and having a larger area than the first electrode region, and the bonding material is in contact with the first electrode region and the second electrode region, and the contact region between the bonding material and the source conductor is formed such that, in the plan view, it does not overlap with the first electrode region but overlaps with the second electrode region.

2. A semiconductor device according to claim 1, characterized in that the thickness of the bonding material on the first electrode region is equal to or greater than the thickness of the bonding material on the second electrode region.

3. A semiconductor device according to claim 1, wherein the semiconductor element has an insulating film between the first electrode region and the second electrode region in the plan view, and the surface of the insulating film is plated with either Au plating, Sn plating, or Ni plating.

4. A semiconductor device according to claim 1, wherein the semiconductor element has an insulating film between the first electrode region and the second electrode region in the plan view, and the surface of the insulating film is subjected to a surface modification treatment by plasma treatment.

5. A semiconductor device according to claim 1, wherein the semiconductor element has an insulating film between the first electrode region and the second electrode region in the plan view, and the insulating film and the bonding material are bonded together with a thermosetting resin.

6. A semiconductor device according to claim 1, wherein the semiconductor device has, on the main surface side of the semiconductor element, a first heat conductive member disposed on the source conductor, and a first cooling member disposed opposite to the semiconductor element with the source conductor and the first heat conductive member in between, for cooling the heat generated by the semiconductor element; and on the surface of the semiconductor element opposite to the main surface, a drain electrode, a drain conductor bonded to the drain electrode via a conductive bonding material, a second heat conductive member disposed on the drain conductor, and a second cooling member disposed opposite to the semiconductor element with the drain conductor and the second heat conductive member in between, for cooling the heat generated by the semiconductor element.

7. A semiconductor device according to claim 6, characterized in that the thermal conductivity of the first heat conduction member and the second heat conduction member is 5 to 10 W / (m·K).

8. A semiconductor device according to claim 1, wherein the source conductor has a base portion, and the base portion is joined to the second electrode region via the bonding material.

9. A semiconductor device according to claim 8, characterized in that the bonding material is in contact with the planar portion and the side surface of the base portion.

10. A power conversion device using a semiconductor device according to any one of claims 1 to 9.

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