Semiconductor device

Abstract

Semiconductor device comprising: a conductive component (4); a semiconductor element (6, 16, 46) having a switching element and held by the conductive component (4) by means of a first bonding material (2); at least one bonding part (6B) provided on an upper surface of the semiconductor element (6, 16, 46) and electrically connected to an electrode of the switching element which is other than the gate electrode; and a conductor (8) which is bonded to the bonding part (6B) by means of a second bonding material (1), wherein the bonding part (6B) and the second bonding material (1) are provided in a region which includes a central part of the upper surface of the semiconductor element (6, 16, 46), the semiconductor element (6, 16, 46) having: an element formation part (46A) which corresponds to a region where the switching element is formed in a top view;and a plurality of signal contact points (46C) provided in a region in the upper surface of the semiconductor element (6, 16, 46) which is other than the element formation part (46A), for sending or receiving a signal for controlling or protecting the switching element, the plurality of signal contact points (46C) being provided in a top view along one side of the semiconductor element (6, 16, 46), and a part of the element formation part (46A) being provided in a top view next to the plurality of signal contact points (46C) on one side of the semiconductor element (6, 16, 46).

Description

Background of the invention Field of invention The present disclosure relates to a semiconductor device. Description of the state of the art WO 2021 / 095 323 A1 describes a semiconductor device in which a rear surface of a switching element is bonded to a metal component and a front surface of the switching element is bonded to an intermediate terminal. The semiconductor device, wired through the intermediate terminal which is made of a plate-like metal, exhibits excellent current-carrying characteristics while achieving a small surface area. Thus, the semiconductor device with this configuration is widely used for various power control devices, such as a control device for air conditioning equipment. DE 10 2022 126 046 A1 discloses a semiconductor device and a power conversion device comprising an insulating layer, a circuit structure, a semiconductor element, an insulating component and a lead electrode. DE 11 2021 007 373 T5 discloses a semiconductor device comprising a heat spreader, a semiconductor element, a metal block, a connector and a sealing material. Summary A semiconductor element, such as a switching element, and a metal component are bonded together by a bonding material. When the semiconductor element is bonded to the metal component, a void may form in the bonding material. If the bonding material contains this void, cooling of the semiconductor element directly above the void is prevented, and the temperature of the semiconductor element rises locally. The present disclosure provides semiconductor devices that reduce a local temperature rise caused by a cavity in a bonding material. This problem is solved by the features of the independent claims. The dependent claims contain advantageous embodiments of the invention. A semiconductor device according to one aspect of the present disclosure comprises a conductive component, a semiconductor element, a bonding element, and a conductor. The semiconductor element includes a switching element. The semiconductor element is held by the conductive component by means of a first bonding material. The bonding element is provided on an upper surface of the semiconductor element. The bonding element is electrically connected to an electrode of the switching element, which is other than a gate electrode. The conductor is bonded to the bonding element by means of a second bonding material. The bonding element and the second bonding material are provided in a region that includes a central portion of the upper surface of the semiconductor element.The semiconductor element comprises an element formation part corresponding to an area where the switching element is formed in a top view, and a plurality of signal contact points provided in an area on the upper surface of the semiconductor element, separate from the element formation part, for sending or receiving a signal to control or protect the switching element. The plurality of signal contact points are arranged along one side of the semiconductor element in a top view. A portion of the element formation part is located adjacent to the plurality of signal contact points on one side of the semiconductor element in a top view. A semiconductor device is provided that reduces a local temperature increase caused by a cavity in a bonding material. These and other tasks, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when viewed in conjunction with the accompanying drawings. Brief description of the drawings Fig. 1 is a top view showing a configuration of a semiconductor device according to embodiment 1. Fig. 2 is a cross-sectional view showing a configuration of the semiconductor device according to embodiment 1. Fig. 3 is a top view showing a configuration of an upper surface of a switching semiconductor element according to embodiment 1. Fig. 4 is a bottom view showing a configuration of a lower surface of the switching semiconductor element according to embodiment 1. Fig. 5 is a top view showing a configuration of an upper surface of a return-flow semiconductor element according to embodiment 1. Fig. 6 is a bottom view showing a configuration of a lower surface of the return-flow semiconductor element according to embodiment 1. Fig. 7 is a flowchart showing a method for manufacturing a semiconductor device.Figure 8 is a cross-sectional view showing a configuration of the semiconductor device according to embodiment 1 after completion. Figure 9 is a top view showing a configuration of a semiconductor device according to embodiment 2. Figure 10 is a cross-sectional view showing a configuration of the semiconductor device according to embodiment 2. Figure 11 is a top view showing a configuration of an upper surface of a switching semiconductor element according to embodiment 2. Figure 12 is a top view showing a configuration of a semiconductor device according to embodiment 3. Figure 13 is a top view showing a configuration of a semiconductor device according to embodiment 4. Figure 14 is a cross-sectional view showing a configuration of the semiconductor device according to embodiment 4.Figure 15 is a top view showing a configuration of a semiconductor device according to embodiment 5. Figure 16 is a top view showing a configuration of an upper surface of a switching semiconductor element according to embodiment 5. Description of preferred embodiments <Ausführungsform 1> Fig. 1 is a top view showing a configuration of a semiconductor device 101 according to embodiment 1. Fig. 2 is a cross-sectional view showing a configuration of the semiconductor device 101 according to embodiment 1. Fig. 2 corresponds to a cross-section along a line AA shown in Fig. 1. The semiconductor device 101 comprises an insulating material 3, a front-side circuit structure 4, a rear-side circuit structure 5, a first bonding material 2, a switching semiconductor element 6, a return-flow semiconductor element 7, a second bonding material 1, a wiring frame 8, a signal terminal 10, a wire 9, and a sealing material 11. In Fig. 1, the sealing material 11 is omitted to facilitate understanding of the internal structure of the semiconductor device 101. The insulating material 3 is made of resin or ceramic. The insulating resin comprises, for example, mainly epoxy resin. Ceramics have, for example, Al₂O₃, Si₃N₄, or Al₃ as a main component. From the perspective of heat dissipation properties, it is preferred that the insulating material 3 be made of a material that exhibits high thermal conductivity and is a thin component. Meanwhile, the thickness of the insulating material 3 is preferably equal to or greater than 100 µm, taking into account the need to ensure insulation properties and structural strength in a single manufacturing process. The front-facing circuit structure 4 is provided on a front surface of the insulating material 3. The front-facing circuit structure 4 is a conductive component and is made of a metal, such as aluminum, an aluminum alloy, copper, or a copper alloy. The front-facing circuit structure 4 holds the switching semiconductor element 6 and the return-flow semiconductor element 7 by means of the first bonding material 2. The front-facing circuit structure 4 not only functions as an electrical circuit but also dissipates heat generated in the switching semiconductor element 6 and the return-flow semiconductor element 7. The front-facing circuit structure 4 has a thickness sufficient to adequately dissipate heat in a planar direction. Although it depends on a planar design, the thickness of the front-facing circuit structure 4 is preferably equal to or greater than 0.4 mm.The front-side circuit structure 4 preferably has a concave-convex part, such as a depression or a slot, as necessary to increase adhesion with the sealing material 11. The rear circuit structure 5 is provided on a rear surface of the insulating material 3. The rear circuit structure 5 is made of a metal, such as aluminum, an aluminum alloy, copper, or a copper alloy. The first bonding material 2 connects the front-side circuit structure 4 and a lower surface of the switching semiconductor element 6. The first bonding material 2 connects the front-side circuit structure 4 and a lower surface of the return-flow semiconductor element 7. The first bonding material 2 is a lead-free solder that, for example, has tin (Sn) as a major component. The first bonding material 2 can be a sintered material that has silver (Ag) or copper (Cu) as a major component. The switching semiconductor element 6 is held by the front-side circuit structure 4 by means of the first bonding material 2. The switching semiconductor element 6 has a switching element (not shown). The switching element is, for example, an insulated-gate bipolar transistor (IGBT) or a metal-oxide-semiconductor field-effect transistor (MOSFET). The switching semiconductor element 6 is made, for example, of a semiconductor such as silicon (Si) or a so-called wide-bandgap semiconductor such as silicon carbide (SiC), gallium oxide (GaN), or diamond. The reverse-flow semiconductor element 7 is held by the front-side circuit structure 4 by means of the first bonding material 2. The reverse-flow semiconductor element 7 includes a diode element. The diode element can be a Schottky blocking diode (SBD) or a rectifier diode with a PN junction. The reverse-flow semiconductor element 7 is made, for example, of a semiconductor such as silicon (Si) or a so-called wide-bandgap semiconductor such as silicon carbide (SiC), gallium oxide (GaN), or diamond. The wiring frame 8 is a conduit and wiring system through which a main current flows in the semiconductor device 101. The wiring frame 8 is bonded to the switching semiconductor element 6 and the return-flow semiconductor element 7 by means of the second bonding material 1. A portion of the wiring frame 8 functions as a main terminal (not shown) that can be connected to a circuit provided in an outer part of the semiconductor device 101. The wiring frame 8 according to embodiment 1 is a component consisting of a metal plate or a machined metal plate. The wiring frame 8 is made of a metal such as aluminum, an aluminum alloy, copper, or a copper alloy. The thickness of the wiring frame 8 depends on a specified current or the width of a main terminal of the semiconductor device 101.The thickness of the wiring frame 8 is preferably equal to or greater than 0.5 mm and equal to or less than 2.0 mm to prevent self-heating of the main connection when current is applied. A metal wire can be used as a conductor instead of the wiring frame 8. The second bonding material 1 connects the switching semiconductor element 6 and the wiring frame 8. The second bonding material 1 connects the return-flow semiconductor element 7 and the wiring frame 8. The second bonding material 1 is a lead-free solder that, for example, has tin as a major component. The second bonding material 1 can be a sintered material that has silver or copper as a major component. One end of the signal terminal 10 serves as a connection point for a circuit provided in an external part of the semiconductor device 101. The signal terminal 10 is, for example, made of copper or a copper alloy. Alternatively, the signal terminal 10 can be made of aluminum or an aluminum alloy to reduce its weight. The thickness of the signal terminal 10 is equal to or greater than 0.2 mm and equal to or less than 1.0 mm. The wire 9 connects each of the five signal contact points 6C provided on the upper surface of the switching semiconductor element 6 to the signal terminal 10. A detailed configuration of the signal contact point 6C is described below. The wire 9 is made of, for example, aluminum, an aluminum alloy, copper, or a copper alloy. The diameter of the wire 9 is equal to or greater than 100 µm and equal to or less than 400 µm.The sealing material 11 seals the insulating material 3, the front circuit structure 4, the first bonding material 2, the switching semiconductor element 6, the return-flow semiconductor element 7, the second bonding material 1, a portion of the wiring frame 8, the wire 9, and a portion of the signal terminal 10. The main terminal of the wiring frame 8, one end of the signal terminal 10, and the rear circuit structure 5 are exposed by the sealing material 11. The sealing material 11 is, for example, made of epoxy resin. A linear coefficient of thermal expansion of the sealing material 11 is preferably equal to or greater than 18 ppm / °C and equal to or less than 24 ppm / °C. Accordingly, detachment of the sealing material 11 from the front circuit structure 4 is prevented, and the occurrence of a fracture in the first bonding material 2 is prevented.Heat is generated in the switching semiconductor element 6 when the switching semiconductor element 6 is operated, thus also increasing the temperature of the sealing material 11. A glass transition temperature Tg is preferably equal to or greater than 175°C, so that a linear coefficient of expansion of the sealing material 11 does not fluctuate due to the increase in temperature. Fig. 3 is a top view showing a configuration of the upper surface of the switching semiconductor element 6 according to embodiment 1. Fig. 4 is a bottom view showing a configuration of the lower surface of the switching semiconductor element 6 according to embodiment 1. The switching semiconductor element 6 has an element formation part 6A, a bonding part 6B, the five signal contact points 6C, and a plurality of gate lines (not shown) on its upper surface. The switching semiconductor element 6 has a bonding part 6D on its lower surface. The element formation part 6A corresponds to a region where the switching element is formed in a top view. The region has a central part (not shown) of the upper surface of the switching semiconductor element 6. The central part has a center point on its upper surface. A plurality of switching elements, each having a channel, are formed in the element formation part 6A according to embodiment 1. Bonding part 6B is located in an area encompassing the central portion of the upper surface of the switching semiconductor element 6. For example, bonding part 6B is located in an area encompassing the center of the switching semiconductor element 6 in a top view. Bonding part 6B is bonded to the wiring frame 8 by the second bonding material 1. The second bonding material 1 is also located in an area encompassing the central portion in a top view. The bonding part 6B is located on an inner side of the element formation part 6A; however, the dimensional relationship between the bonding part 6B and the element formation part 6A is not limited. The bonding part 6B can be the same size as the element formation part 6A. The bonding part 6B is formed from a metal layer exhibiting fine wettability, such as Ni, Au, Cu, or Ag. The bonding part 6B is electrically connected to an electrode of the switching element that is other than a gate electrode. For example, if the switching element is an IGBT, the bonding part 6B is electrically connected to an emitter electrode. That is, the bonding part 6B itself functions as an emitter electrode. Five signal contact points 6C are provided on the upper surface of the switching semiconductor element 6. Each signal contact point 6C is located in a region on the upper surface of the switching semiconductor element 6 that is distinct from the element formation part 6A. According to embodiment 1, the five signal contact points 6C are arranged in a row along one side of an outline of the switching semiconductor element 6 in a top view. Each signal contact point 6C is formed from a metal layer. Each signal contact point 6C is a contact point for sending or receiving a signal to control or protect the switching element. The signal is, for example, a gate signal (G), an emitter signal (E), a current sensor signal (Cs), and a temperature sensor signal (K, A). In other words, one of the five signal contact points 6C is a gate contact point.The gate contact point is electrically connected to a gate electrode of each switching element via a plurality of gate lines (not shown). The number of signal contact points 6C is not limited to five. Therefore, four or fewer, or six or more, can also be used. The majority of gate lines are configured to cross the upper surface of the switching semiconductor element 6. Each gate line is configured to avoid passing through the central portion of the switching semiconductor element 6. For example, the gate line is configured to avoid passing through the center of the switching semiconductor element 6. Each gate line is electrically connected to the gate electrode of each switching element. The bonding part 6D is provided on the lower surface of the switching semiconductor element 6. According to embodiment 1, the bonding part 6D is provided on the entire lower surface of the switching semiconductor element 6. The bonding part 6D is formed from a metal layer exhibiting fine wettability, such as Ni, Au, Cu, or Ag. The bonding part 6D is electrically connected to an electrode of the switching element that is not connected to the bonding part 6B and is other than a gate electrode. For example, if the switching element is an IGBT, the bonding part 6D is electrically connected to a collector electrode. That is, the bonding part 6D itself acts as a collector electrode. The bonding part 6D is bonded to the front-side circuit structure 4 by the first bonding material 2. If the switching element is an IGBT, a main current corresponding to a gate signal applied to the gate electrode flows between the collector electrode formed in the bonding part 6D and the emitter electrode formed in the bonding part 6B. Fig. 5 is a top view showing a configuration of an upper surface of the return flow semiconductor element 7 according to embodiment 1. Fig. 6 is a bottom view showing a configuration of the lower surface of the return flow semiconductor element 7 according to embodiment 1. The return flow semiconductor element 7 has an element formation part 7A and a bonding part 7B on its upper surface. The return flow semiconductor element 7 has a bonding part 7D on its lower surface. Element formation part 7A corresponds to an area where the diode element is formed in a top view. Bonding part 7B is located on the upper surface of the return-flow semiconductor element 7. Bonding part 7B is bonded to the wiring frame 8 by the second bonding material 1. Bonding part 7B is located on the inner side of the element formation part 7A; however, the dimensional ratio between bonding part 7B and element formation part 7A is not limited to this. Bonding part 7B can be the same size as element formation part 7A. Bonding part 7B is formed from a metal layer exhibiting fine wettability, such as Ni, Au, Cu, or Ag. The bonding element 7D is provided on the lower surface of the return-flow semiconductor element 7. According to embodiment 1, the bonding element 7D is provided on the entire lower surface of the return-flow semiconductor element 7. The bonding element 7D is formed from a metal layer exhibiting fine wettability, such as Ni, Au, Cu, or Ag. The bonding element 7D is bonded to the front-side circuit structure 4 by the first bonding material 2. The bonding part 7B and the bonding part 7D of the return-flow semiconductor element 7 can be made of the same material as that of the bonding part 6B and the bonding part 6D of the switching semiconductor element 6. Fig. 7 is a flowchart illustrating a process for manufacturing the semiconductor device 101. In step S1, the insulating material 3, which has the front circuit structure 4 and the rear circuit structure 5, is prepared. In step S2, the switching semiconductor element 6 and the return-flow semiconductor element 7 are attached to the front-side circuit structure 4 using the first bonding material 2. In this step S2, the first bonding material 2 is initially placed between the bonding part 6D of the switching semiconductor element 6 and the front-side circuit structure 4, and between the bonding part 7D of the return-flow semiconductor element 7 and the front-side circuit structure 4. A bonding process is then performed on the switching semiconductor element 6, the return-flow semiconductor element 7, the first bonding material 2, and the front-side circuit structure 4 under a predetermined atmosphere, temperature, and pressure. Accordingly, the bonding parts 6D and 7D are each bonded to the front-side circuit structure 4 by the first bonding material 2. In step S3, the switching semiconductor element 6 and the return-flow semiconductor element 7 are bonded to the wiring frame 8 using the second bonding material 1. In this step S3, the second bonding material 1 is first applied between the bonding part 6B of the switching semiconductor element 6 and the wiring frame 8, and then between the bonding part 7B of the return-flow semiconductor element 7 and the wiring frame 8. A bonding process is then performed on the switching semiconductor element 6, the return-flow semiconductor element 7, the second bonding material 1, and the wiring frame 8 under a predetermined atmosphere, temperature, and pressure. Accordingly, the bonding parts 6B and 7B are bonded to the wiring frame 8 by the second bonding material 1. Furthermore, in this step S3, a connecting part (not shown), where the wiring frame 8 and the front circuit structure 4 are connected, can be bonded through the second bonding material 1.The switching semiconductor element 6 and the wiring frame 8 can be bonded by ultrasonic (US) bonding without using the second bonding material 1. In step S4, each of the five signal contact points 6C is connected to the signal terminal 10 via the wire 9. In step S5, the sealing material 11 seals the insulating material 3, the front-side circuit structure 4, the first bonding material 2, the switching semiconductor element 6, the return-flow semiconductor element 7, the second bonding material 1, part of the wiring frame 8, the wire 9 and part of the signal connector 10. The semiconductor device 101 is completed by the steps S1 to S5 described above. In steps S2 and S3, the bonding of bonding parts 6D and 7D to the front-facing circuit structure 4 and the bonding of bonding parts 6B and 7B to the wiring frame 8 can be performed simultaneously. Performing the bonding operations concurrently improves productivity. Fig. 8 is a cross-sectional view showing a configuration of the semiconductor device 101 according to embodiment 1 after completion. Fig. 8 corresponds to a cross-section along a line AA shown in Fig. 1. The semiconductor device 101 has a cavity 2A in the first bonding material 2 of the switching semiconductor element 6. For the purposes of this description, it is assumed that the cavity 2A is located, for example, on a lower side of a central part of the switching semiconductor element 6. The cavity 2A is formed when the switching semiconductor element 6 is bonded to the front circuit structure 4 by means of the first bonding material 2. The formation of the cavity 2A is caused, for example, by outgassing from the bonding part 6B or the front circuit structure 4, or by air entrapment during the positioning of the switching semiconductor element 6 onto the first bonding material 2. Heat is generated in the switching semiconductor element 6 during operation, that is, during energy transfer. The extent of the temperature rise due to heat generation is not uniform across the surface of the switching semiconductor element 6. The extent of the temperature rise in the central part of the switching semiconductor element 6 is greater than that in an outer circumferential part. The cavity 2A also causes a temperature rise. That is, if the cavity 2A is formed in the first bonding material 2, the thermal conductivity of the cavity 2A is almost zero. Thus, if the cavity is positioned as shown in Fig. 8, a local temperature rise occurs in the central part, corresponding to the area immediately above the cavity 2A. That is, the extent of the temperature rise in the central part is doubled. In the semiconductor device 101 according to the present embodiment, the bonding part 6B is provided in a region directly above the cavity 2A, that is, a region encompassing the central part. Furthermore, the second bonding material 1 is provided on the bonding part 6B. Thus, even if the cavity 2A is located on a lower side of the central part of the switching semiconductor element 6, heat generated in the central part is absorbed by the second bonding material 1 and then dissipated. As a result, a local temperature rise of the switching semiconductor element 6 is prevented. In summary, the semiconductor device 101 according to embodiment 1 comprises the front-facing circuit structure 4, the switching semiconductor element 6, the bonding part 6B, and the wiring frame 8. The switching semiconductor element 6 includes the switching element. The switching semiconductor element 6 is held by the front-facing circuit structure 4 by means of the first bonding material 2. The bonding part 6B is provided on the upper surface of the switching semiconductor element 6. The bonding part 6B is electrically connected to the electrode of the switching element, which is different from the gate electrode. The wiring frame 8 is bonded to the bonding part 6B by means of the second bonding material 1. The bonding part 6B and the second bonding material 1 are provided in a region that includes the central part of the upper surface of the switching semiconductor element 6. Such a semiconductor device 101 reduces a local temperature increase caused by the cavity 2A formed in the first bonding material 2. An upper temperature limit is defined in the switching semiconductor element 6 and the return-flow semiconductor element 7 to ensure, for example, the reliability of the lifetime of the semiconductor device 101. The cavity 2A generates a local temperature rise; therefore, the cavity 2A must be managed so that the temperature of the switching semiconductor element 6 and the temperature of the return-flow semiconductor element 7 do not exceed the preset upper temperature limit. In particular, the heat generation of the switching semiconductor element 6 is greater than that of the return-flow semiconductor element 7; therefore, the management of the cavity 2A in the switching semiconductor element 6 must be more stringent than in the return-flow semiconductor element 7. For example, the temperature limit for the cavity 2A occurring in the switching semiconductor element 6 is stricter than that for the cavity 2A occurring in the return-flow semiconductor element 7.Thus, the switching semiconductor element 6 exhibits a problem of deterioration in productivity, that is, a slight increase in the defect rate, due to the cavity 2A. In the semiconductor device 101 according to the present embodiment, the bonding part 6B and the second bonding material 1 are located in a region directly above the cavity 2A. Heat generated in the central part of the switching semiconductor element 6 is transferred to and distributed by the second bonding material 1 and the wiring frame 8. As a result, a local temperature rise of the switching semiconductor element 6 is prevented. The semiconductor device 101 according to embodiment 1 can achieve an expansion of a regulated permissible area with respect to the cavity 2A, that is, a reduction of a specified area. The semiconductor device 101 can easily handle the cavity 2A and increase reliability and productivity. The cavity 2A can be formed in either the switching semiconductor element 6 or the return-flow semiconductor element 7. However, the heat generation area of ​​the switching semiconductor element 6 is larger than that of the return-flow semiconductor element 7; therefore, the aforementioned effect appears significant in a configuration where the cavity 2A is formed in the first bonding material 2 of the switching semiconductor element 6. The number of bonding elements 6B provided on the upper surface of the switching semiconductor element 6 is only one in the semiconductor device 101. According to such a configuration, the second bonding material 1 is easily provided in the manufacturing process, and productivity is improved. The gate conductor is designed so that it does not pass through the central part of the switching semiconductor element 6. According to this configuration, the bonding part 6B is located in the central part of the switching semiconductor element 6, where heat is concentrated. This improves heat dissipation properties and prevents a temperature rise. The switching semiconductor element 6 and the return-flow semiconductor element 7 are formed by a wide-bandgap semiconductor, thus improving the dielectric strength properties of the switching element and the diode element. A high permissible current density is also achieved, allowing the switching element and the diode element to be miniaturized. Minimizing the semiconductor device 101 is achieved by using this miniaturized switching element and diode element. (Modification example 1 of embodiment 1) An area of ​​the first bonding material 2 is equal to or greater than 50% of an area of ​​the second bonding material 1. According to this configuration, the balance between the bonding part 6B on the front side of the switching semiconductor element 6 and the bonding part 6D on the back side is improved. As a consequence, a concave bulge in the front direction, which can occur in the switching semiconductor element 6, is reduced. This reduction of concave bulge prevents the cavity 2A, which occurs in the first bonding material 2, from being concentrated on a central portion of the switching semiconductor element 6. (Modification example 2 of embodiment 1) The horizontal-to-vertical ratio of the switching semiconductor element 6 in a top view is equal to or greater than 1.5 and equal to or less than 2.5. According to such a configuration, the cavity 2A in the central part of the switching semiconductor element 6 is easily separated from an outer part of a long side of the switching semiconductor element 6. In addition to the horizontal-vertical ratio described above, the area of ​​the switching semiconductor element 6 is equal to or less than 150 mm². In such a configuration, the distance from the central part of the switching semiconductor element 6 to its long side is small. The cavity 2A, which occurs in the central part, is more easily separated from the outer part by the long side. Meanwhile, in addition to the horizontal-vertical ratio described above, the area of ​​the switching semiconductor element 6 can be equal to or greater than 150 mm². In the size described above, the majority of gate lines must be arranged to make a voltage application to the gate uniform; however, the influence of the cavity can be reduced by applying the horizontal-vertical ratio described above in addition to the configuration of the present embodiment. (Modification example 3 of embodiment 1) The thickness of the switching semiconductor element 6 is equal to or less than 150 µm. In such a configuration, the flexural strength of the switching semiconductor element 6 is reduced, thus warping easily occurs. Even if the cavity 2A appears in the central part due to the warping, the bonding part 6B and the second bonding material 1 are located directly above the cavity 2A, so a local temperature rise is minimal. (Modification example 4 of embodiment 1) The switching semiconductor element 6 and the reverse-flow semiconductor element 7 according to embodiment 1 are distinct elements, but can be integrated elements formed in the same semiconductor substrate. For example, the switching semiconductor element 6 comprises a reverse-conducting IGBT (RC-IGBT) in which an IGBT and a diode element are formed as a switching element in a semiconductor substrate. When the switching element is the RC-IGBT, the number of elements is reduced and productivity is improved. <Ausführungsform 2> Fig. 9 is a top view showing a configuration of a semiconductor device 102 according to embodiment 2. Fig. 10 is a cross-sectional view showing a configuration of the semiconductor device 102 according to embodiment 2. Fig. 10 corresponds to a cross-section along a line BB shown in Fig. 9. The semiconductor device 102 has a switching semiconductor element 16 instead of the switching semiconductor element 6 described in embodiment 1. Fig. 11 is a top view showing a configuration of an upper surface of the switching semiconductor element 16 according to embodiment 2. The switching semiconductor element 16 comprises a first element formation part 16A, two second element formation parts 26A, a first bonding part 16B, two second bonding parts 26B, five signal contact points 16C, and a plurality of gate lines (not shown) on the upper surface of the switching semiconductor element 16. The first element formation part 16A and the two second element formation parts 26A correspond to a configuration such that the element formation part 6A is divided into three regions according to embodiment 1. Similarly, the first bonding part 16B and the two second bonding parts 26B correspond to a configuration such that the bonding part 6B is divided into three regions according to embodiment 1. The configuration of a lower surface of the switching semiconductor element 16 is similar to that of the switching semiconductor element 6 according to embodiment 1. The first element formation part 16A and the two second element formation parts 26A correspond to a region where the switching element is formed in a top view. The first element formation part 16A comprises a central portion (not shown) of the upper surface of the switching semiconductor element 16. The two second element formation parts 26A are arranged on both sides of the first element formation part 16A. The first bonding part 16B is provided in a region encompassing the central portion of the switching semiconductor element 16. The first bonding part 16B is preferably arranged such that a center of the first bonding part 16B overlaps with the central portion of the switching semiconductor element 16. The two second bonding parts 26B are provided in a different region than the first bonding part 16B. Here, the two second bonding parts 26B are provided on both sides of the first bonding part 16B. The first bonding part 16B and the second bonding parts 26B are bonded to the wiring frame by the second bonding material 1. The second bonding material 1 is also provided in an area that, in a top view, encompasses the central part. The configuration of signal contact point 16C is similar to that of signal contact point 6C according to embodiment 1. The majority of gate lines are arranged to cross the upper surface of the switching semiconductor element 16. Each gate line is arranged to avoid passing through the central portion of the switching semiconductor element 16. Each gate line is located in a different region than the first bonding portion 16B. As a measure to improve current-carrying capacity, increasing the area of ​​the switching semiconductor element 16 is considered. However, the balance of applying a gate voltage across the surface of the switching semiconductor element 16 deteriorates with increasing its area, and the short-circuit resistance decreases. If the gate line is positioned to cross the central part, the balance of applying the gate voltage can be improved; however, the bonding part 6B and the second bonding material 1 cannot be located in the central part. Thus, if the cavity 2A is formed in the central part, a local temperature rise occurs in the central part. In the semiconductor device 102, the gate lead is not located in the central part of the switching semiconductor element 16; however, the majority of gate leads are arranged in a different region than the central part, thus improving the balance of the gate voltage application. The first bonding part 16B and the first bonding material 2 are located in the central part of the switching semiconductor element 16. Therefore, even if the area of ​​the switching semiconductor element 16 is increased, the semiconductor device 102 prevents a deterioration of the gate voltage balance and suppresses a temperature rise caused by the cavity 2A formed on the lower side of the central part. The number of divided bonding parts 6B is not limited to three. The bonding part 6B is preferably divided by an odd number equal to or greater than three, as necessary. In other words, the semiconductor device 102 preferably comprises the first bonding part 16B provided in the central part and the even number of second bonding parts 26B provided around the first bonding part 16B. (Modification example 1 of embodiment 2) The horizontal-to-vertical ratio of the switching semiconductor element 16 in a top view is equal to or greater than 1.5 and equal to or less than 2.5. According to such a configuration, the cavity 2A in the central part is slightly separated from an outer part by a long side of the switching semiconductor element 16. The area of ​​the switching semiconductor element 16 is equal to or greater than 150 mm². The current-carrying capacity increases with an increase in the area of ​​the switching semiconductor element 16. The first bonding part 16B and the second bonding material 1 are arranged in the central part, thus reducing the temperature rise caused by the cavity 2A. Furthermore, the majority of gate lines are arranged in this way, thereby improving the uniformity of the gate voltage. <Ausführungsform 3> Fig. 12 is a top view showing a configuration of a semiconductor device 103 according to embodiment 3. The semiconductor device 103 comprises a switching semiconductor element 26 and a switching semiconductor element 36. The switching semiconductor element 26 and the switching semiconductor element 36 have the same configuration. The switching semiconductor element 26 and the switching semiconductor element 36 are connected in parallel. The number of switching semiconductor elements connected in parallel is not limited to two. Three or more switching semiconductor elements can be connected in parallel, as required. The emitter signal (E), the current sensor signal (Cs), and the temperature sensor signal (K, A) are taken only from switching semiconductor element 26. The gate signal (G) is taken from both elements of switching semiconductor element 26 and switching semiconductor element 36. The emitter signal (E), the current sensor signal (Cs), and the temperature sensor signal (K, A) can be taken from switching semiconductor element 26 and switching semiconductor element 36 to improve a protective function. The use of multiple small elements instead of one large element increases current carrying capacity while improving the balance of gate voltage application. The 2A cavity is virtually nonexistent in the second bonding material 1. Bonding part 6B is simplified, further reducing the occurrence of the 2A cavity and thus lowering the defect rate. <Ausführungsform 4> Fig. 13 is a top view showing a configuration of a semiconductor device 104 according to embodiment 4. Fig. 14 is a cross-sectional view showing a configuration of a semiconductor device 104 according to embodiment 4. Fig. 14 corresponds to a cross-section along a line CC shown in Fig. 13. The wiring frame 8 has a through-hole 8A in a bonding surface where the wiring frame 8 is bonded to the bonding part 6B. The through-hole 8A is designed so that, in a top view, it does not overlap with the central part of the switching semiconductor element 6. In the bonding process between the wiring frame 8 and the bonding part 6B, if there is an excess of the second bonding material 1 supplied between the wiring frame 8 and the bonding part 6B, there is a possibility that the excess second bonding material 1 will flow out of the bonding part 6B. The through-hole 8A guides the excess second bonding material 1 located between the wiring frame 8 and the bonding part 6B into the through-hole 8A, thus preventing the second bonding material 1 from flowing out of the bonding part 6B. However, if a bonding material with high flowability, such as a solder, is used as the second bonding material 1, the shape of the second bonding material 1 immediately below the through-hole 8A is not stable. For example, if the amount of solder supplied is small, the thickness of the second bonding material 1 immediately below the through-hole 8A will be less than that around the through-hole 8A due to the influence of surface tension. In such a case, the effect of reducing the temperature rise caused by the cavity 2A immediately below the through-hole will be small. In the semiconductor device 104, the through-hole 8A is designed so that it does not overlap with the central part of the switching semiconductor element 6. This ensures that the thickness of the second bonding material 1 is maintained even in the central part of the switching semiconductor element 6. The second bonding material 1 prevents a temperature rise caused by the cavity 2A that occurs in the central part of the switching semiconductor element 6. <Ausführungsform 5> Fig. 15 is a top view showing a configuration of a semiconductor device 105 according to an embodiment 5 according to the invention. The semiconductor device 105 has a switching semiconductor element 46 instead of the switching semiconductor element 6 described in embodiment 1. Fig. 16 is a top view showing a configuration according to the invention of an upper surface of the switching semiconductor element 46 according to embodiment 5. The switching semiconductor element 46 has an element formation part 46A, a bonding part 46B, four signal contact points 46C and a plurality of gate lines (not shown) on the upper surface of the switching semiconductor element 46. The element formation part 46A corresponds to an area where the switching element is formed in a top view. Part of the element formation part 46A is provided next to the four signal contact points 46C on one side of the switching semiconductor element 46 in a top view. Bonding part 46B is similar to bonding part 6B according to embodiment 1. The four signal contact points 46C are provided in an area on the upper surface of the switching semiconductor element 46 that is distinct from the element formation part 46A. The four signal contact points 46C are arranged in a top view along one side of the switching semiconductor element 46. Each signal contact point 46C is a contact point for sending or receiving a signal to control or protect the switching element. The signal is the gate signal (G), the current sensor signal (Cs), and the temperature sensor signal (K, A). The element formation part 46A extends from a central section between two adjacent signal contact points of four signal contact points 46C. The signal contact point 46C and the element formation part 46A are arranged side by side on one side. The element formation part 46A functions as a signal contact point for the emitter signal (E) on one side of the switching semiconductor element 46. Accordingly, the wire 9 connects the signal terminal 10 and the element formation part 46A on one side of the switching semiconductor element 46. The area of ​​the element formation part 46A is larger than that of the element formation part 6A described in embodiment 1. Thus, even if the switching semiconductor element 6 and the switching semiconductor element 46 have the same area, the loss of the semiconductor device 105 is improved more than the loss of the semiconductor device 101 according to embodiment 1. The semiconductor device 105, which exhibits high efficiency, is achieved. In the present disclosure, any embodiment can be combined arbitrarily, or any embodiment can be suitably varied or omitted. The aspects of the present revelation are summarized below and described in an appendix. (Appendix 1) Semiconductor device comprising: a conductive component; a semiconductor element having a switching element and held by the conductive component by means of a first bonding material; at least one bonding part provided on an upper surface of the semiconductor element and electrically connected to an electrode of the switching element other than the gate electrode; and a conductor bonded to the bonding part by means of a second bonding material, wherein the bonding part and the second bonding material are provided in a region comprising a central part of the upper surface of the semiconductor element. (Appendix 2) Semiconductor device according to Appendix 1, further comprising a sealing material that seals the conductive component, the first bonding material, the semiconductor element, the bonding part, the second bonding material and a part of the conductor. (Appendix 3) Semiconductor device according to Appendix 1 or 2, wherein the total number of bonding parts provided on the upper surface of the semiconductor element is only one. (Appendix 4) Semiconductor device according to one of Appendices 1 to 3, further comprising a plurality of gate lines which are provided such that they cross the upper surface of the semiconductor element and are electrically connected to the gate electrode of the switching element, wherein the plurality of gate lines are provided such that they do not pass through the central part. (Appendix 5) Semiconductor device according to one of Appendices 1 to 3, further comprising a plurality of gate lines which are provided such that they cross the upper surface of the semiconductor element and are electrically connected to the gate electrode of the switching element, wherein the bonding part comprises a first bonding part which is provided on a region which includes the central part, and a plurality of second bonding parts which are provided on a region which is other than the first bonding part, and the plurality of gate lines are provided such that they do not pass through the central part. (Appendix 6) Semiconductor device according to any of Appendices 1 to 5, wherein an area of ​​the first bonding material is equal to or greater than 50% of an area of ​​the second bonding material. (Appendix 7) Semiconductor device according to any of Appendices 1 to 6, wherein a horizontal-vertical ratio of the semiconductor element in a top view is equal to or greater than 1.5 and equal to or less than 2.5, and an area of ​​the semiconductor element is equal to or less than 150 mm2. (Appendix 8) Semiconductor device according to any of Appendices 1 to 6, wherein a horizontal-vertical ratio of the semiconductor element in a top view is equal to or greater than 1.5 and equal to or less than 2.5, and an area of ​​the semiconductor element is equal to or greater than 150 mm2. (Appendix 9) Semiconductor device according to any of Appendices 1 to 8, wherein the thickness of the semiconductor element is equal to or less than 150 µm. (Appendix 10) Semiconductor device according to any one of Appendices 1 to 9, wherein the semiconductor element comprises: an element forming part corresponding to an area where the switching element is formed in a top view; and a plurality of signal contact points provided in an area in the upper surface of the semiconductor element other than the element forming part, for sending or receiving a signal for controlling or protecting the switching element, the plurality of signal contact points being provided in a top view along one side of the semiconductor element, and a portion of the element forming part being provided in a top view next to the plurality of signal contact points on one side of the semiconductor element. (Appendix 11) Semiconductor device according to any of Appendices 1 to 10, wherein the conductor has a through-hole in a bonding surface where the conductor is bonded to the bonding part, and the through-hole is provided such that it does not overlap with the central part in a top view. (Appendix 12) Semiconductor device according to any of Appendices 1 to 11, wherein the semiconductor element comprises an RC-IGBT as the switching element. (Appendix 13) Semiconductor device according to one of Appendices 1 to 12, wherein the semiconductor element is composed of a wide bandgap semiconductor. (Appendix 14) Semiconductor device according to Appendix 13, wherein the wide bandgap semiconductor comprises silicon carbide, a gallium nitride series material or diamond. (Appendix 15) Semiconductor device according to any of Appendices 1 to 14, wherein the first bonding material has a cavity, and the cavity is located on a lower side of the central part. (Appendix 16) Semiconductor device comprising: a conductive component; a plurality of semiconductor elements, each comprising a switching element and held by the conductive component by means of a first bonding material; a bonding part provided on an upper surface of each of the plurality of semiconductor elements and electrically connected to an electrode of the switching element other than a gate electrode; and a conductor bonded to the bonding part by means of a second bonding material, wherein the plurality of semiconductor elements are connected in parallel, and the bonding part and the second bonding material are provided in a region comprising a central part of the upper surface of each of the plurality of semiconductor elements. Although the invention has been shown and described in detail, the foregoing description is descriptive in all aspects and not limiting. It is therefore understood that numerous modifications and variations can be designed without departing from the scope of protection of the invention.

Claims

Semiconductor device comprising: a conductive component (4); a semiconductor element (6, 16, 46) having a switching element and held by the conductive component (4) by means of a first bonding material (2); at least one bonding part (6B) provided on an upper surface of the semiconductor element (6, 16, 46) and electrically connected to an electrode of the switching element which is other than the gate electrode; and a conductor (8) which is bonded to the bonding part (6B) by means of a second bonding material (1), wherein the bonding part (6B) and the second bonding material (1) are provided in a region which includes a central part of the upper surface of the semiconductor element (6, 16, 46), the semiconductor element (6, 16, 46) having: an element formation part (46A) which corresponds to a region where the switching element is formed in a top view;and a plurality of signal contact points (46C) provided in a region in the upper surface of the semiconductor element (6, 16, 46) which is other than the element formation part (46A), for sending or receiving a signal for controlling or protecting the switching element, the plurality of signal contact points (46C) being provided in a top view along one side of the semiconductor element (6, 16, 46), and a part of the element formation part (46A) being provided in a top view next to the plurality of signal contact points (46C) on one side of the semiconductor element (6, 16, 46). Semiconductor device according to claim 1, further comprising: a sealing material (11) that seals the conductive component (4), the first bonding material (2), the semiconductor element (6, 16, 46), the bonding part (6B), the second bonding material (1) and a part of the conductor (8). Semiconductor device according to claim 1 or 2, wherein the total number of bonding parts (6B) provided on the upper surface of the semiconductor element (6) is only one. Semiconductor device according to one of claims 1 to 3, further comprising a plurality of gate lines which are provided such that they cross the upper surface of the semiconductor element (6) and are electrically connected to the gate electrode of the switching element, wherein the plurality of gate lines are provided such that they do not pass through the central part. Semiconductor device according to one of claims 1 to 3, further comprising a plurality of gate lines which are provided such that they cross the upper surface of the semiconductor element (16) and are electrically connected to the gate electrode of the switching element, wherein the bonding part (6B) comprises a first bonding part (16B) which is provided on a region which includes the central part, and a plurality of second bonding parts (26B) which are provided on a region which is other than the first bonding part (16B), and the plurality of gate lines are provided such that they do not pass through the central part. Semiconductor device according to any one of claims 1 to 5, wherein an area of ​​the first bonding material (2) is equal to or greater than 50% of an area of ​​the second bonding material (1). Semiconductor device according to any one of claims 1 to 6, wherein the horizontal-vertical ratio of the semiconductor element (6) in a top view is equal to or greater than 1.5 and equal to or less than 2.5, and the area of ​​the semiconductor element (6) is equal to or less than 150 mm2. Semiconductor device according to any one of claims 1 to 6, wherein the horizontal-vertical ratio of the semiconductor element (6, 16) in a top view is equal to or greater than 1.5 and equal to or less than 2.5, and the area of ​​the semiconductor element (6, 16) is equal to or greater than 150 mm2. Semiconductor device according to any one of claims 1 to 8, wherein the thickness of the semiconductor element (6) is equal to or less than 150 µm. Semiconductor device according to any one of claims 1 to 9, wherein the conductor (8) has a through hole (8A) in a bonding surface where the conductor (8) is bonded to the bonding part (6B), and the through hole (8A) is provided such that it does not overlap with the central part in a top view. Semiconductor device according to one of claims 1 to 10, wherein the semiconductor element (6, 16, 46) comprises an RC-IGBT as the switching element. Semiconductor device according to one of claims 1 to 11, wherein the semiconductor element (6, 16, 46) is composed of a wide bandgap semiconductor. Semiconductor device according to claim 12, wherein the wide bandgap semiconductor comprises silicon carbide, a gallium nitride series material or diamond. Semiconductor device according to any one of claims 1 to 13, wherein the first bonding material (2) has a cavity (2A), and the cavity (2A) is located on a lower side of the central part. Semiconductor device comprising: a conductive component (4); a plurality of semiconductor elements (26, 36), each comprising a switching element and held by the conductive component (4) by means of a first bonding material (2); a bonding part (6B) provided on an upper surface of each of the plurality of semiconductor elements (26, 36) and electrically connected to an electrode of the switching element, which is other than a gate electrode;and a conductor (8) which is bonded to the bonding part (6B) by means of a second bonding material (1), wherein the plurality of semiconductor elements (26, 36) are connected in parallel to each other, the bonding part (6B) and the second bonding material (1) are provided in a region which includes a central part of the upper surface of each of the plurality of semiconductor elements (26, 36), each of the plurality of semiconductor elements (26, 36) having: an element formation part (46A) which corresponds to a region where the switching element is formed in a top view;and a plurality of signal contact points (46C) provided in a region in the upper surface of each plurality of semiconductor elements (26, 36) other than the element formation part (46A), for sending or receiving a signal for controlling or protecting the switching element, the plurality of signal contact points (46C) being provided in a top view along one side of each plurality of semiconductor elements (26, 36), and a part of the element formation part (46A) being provided in a top view adjacent to the plurality of signal contact points (46C) on one side of each plurality of semiconductor elements (26, 36).

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