Semiconductor Devices

Abstract

This semiconductor device includes: a first terminal; a second terminal; a first diode element which is connected between the first terminal and the second terminal, and has a first breakdown voltage having junction temperature dependency; and a first switching element connected in parallel to the first diode element between the first terminal and the second terminal, and having a second breakdown voltage having junction temperature dependency. The second breakdown voltage within the range of a junction temperature of 50-70°C is lower than the first breakdown voltage within the range of a junction temperature of 50-70°C, and the second breakdown voltage includes a third breakdown voltage when the junction temperature is 50°C, and a fourth breakdown voltage when the junction temperature is 300°C. The first breakdown voltage within the range of the junction temperature of 50-70°C is between the third breakdown voltage and the fourth breakdown voltage.

Description

[Technical Field]

[0001] The present disclosure relates to semiconductor devices.

[0002] This application claims priority to Japanese Application No. 2021-009883, filed on January 25, 2021, and incorporates by reference all of the contents of said Japanese application. [Background technology]

[0003] As a semiconductor device used in a power module, a semiconductor device has been proposed in which a switching element and a diode element are connected in parallel between two terminals, and the breakdown voltage of the diode element is made smaller than the breakdown voltage of the switching element (Patent Documents 1 and 2). Also, a semiconductor device has been proposed in which the breakdown voltage of the switching element is made smaller than the breakdown voltage of the diode element (Patent Document 3). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2013-229956 [Patent Document 2] Japanese Patent Application Publication No. 2017-153064 [Patent Document 3] Japanese Patent Publication No. 2013-236507 Summary of the Invention

[0005] The semiconductor device of the present disclosure includes a first terminal, a second terminal, a first diode element connected between the first terminal and the second terminal and having a first breakdown voltage that is junction temperature dependent, and a first switching element connected in parallel to the first diode element between the first terminal and the second terminal and having a second breakdown voltage that is junction temperature dependent, wherein the second breakdown voltage within a junction temperature range of 50°C to 70°C is lower than the first breakdown voltage within a junction temperature range of 50°C to 70°C, the second breakdown voltage includes a third breakdown voltage when the junction temperature is 50°C and a fourth breakdown voltage when the junction temperature is 300°C, and the first breakdown voltage within a junction temperature range of 50°C to 70°C is between the third breakdown voltage and the fourth breakdown voltage. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a perspective view showing a semiconductor device according to an embodiment. [Figure 2] FIG. 2 is a top view showing the semiconductor device according to the embodiment. [Figure 3] FIG. 3 is a cross-sectional view showing the relationship between the heat sink, the first insulating substrate, and the second insulating substrate in the semiconductor device according to the embodiment. [Figure 4] FIG. 4 is a cross-sectional view showing the first transistor. [Figure 5] FIG. 5 is a cross-sectional view showing the first diode. [Figure 6] FIG. 6 is a cross-sectional view showing a second transistor. [Figure 7] FIG. 7 is a cross-sectional view showing the second diode. [Figure 8] FIG. 8 is a circuit diagram showing a semiconductor device according to the embodiment. [Figure 9] FIG. 9 is a schematic diagram (part 1) showing the operation of the semiconductor device according to the embodiment. [Figure 10] FIG. 10 is a schematic diagram (part 2) showing the operation of the semiconductor device according to the embodiment. [Figure 11] FIG. 11 is a schematic diagram (part 3) showing the operation of the semiconductor device according to the embodiment. [Figure 12] FIG. 12 is a schematic diagram (part 4) illustrating the operation of the semiconductor device according to the embodiment. [Figure 13] FIG. 13 is a diagram illustrating an example of the characteristics of the first transistor, the second transistor, the first diode, and the second diode. [Figure 14] FIG. 14 is a timing chart showing the changes in voltage and current in the lower arm when transitioning to a dynamic avalanche state. [Figure 15] FIG. 15 is a diagram showing another example of the characteristics of the first transistor, the second transistor, the first diode, and the second diode. DETAILED DESCRIPTION OF THE INVENTION

[0007] [Problem to be solved by this disclosure] Conventional semiconductor devices may not be able to provide sufficient avalanche resistance.

[0008] An object of the present disclosure is to provide a semiconductor device that can improve avalanche resistance.

[0009] [Effects of this disclosure] According to the present disclosure, avalanche resistance can be improved.

[0010] The embodiments for carrying out the invention are described below.

[0011] [Description of the embodiments of the present disclosure] First, embodiments of the present disclosure will be listed and described. In the following description, the same or corresponding elements will be denoted by the same reference numerals, and the same description will not be repeated.

[0012] [1] A semiconductor device according to one embodiment of the present disclosure includes a first terminal, a second terminal, a first diode element connected between the first terminal and the second terminal and having a first breakdown voltage that is junction temperature dependent, and a first switching element connected in parallel to the first diode element between the first terminal and the second terminal and having a second breakdown voltage that is junction temperature dependent, wherein the second breakdown voltage within a junction temperature range of 50°C to 70°C is lower than the first breakdown voltage within a junction temperature range of 50°C to 70°C, the second breakdown voltage includes a third breakdown voltage at a junction temperature of 50°C and a fourth breakdown voltage at a junction temperature of 300°C, and the first breakdown voltage within a junction temperature range of 50°C to 70°C is between the third breakdown voltage and the fourth breakdown voltage.

[0013] In this semiconductor device, when the device transitions to a dynamic avalanche state, the first switching element breaks down before the first diode element. As the first switching element breaks down, the inter-terminal voltage between the first terminal and the second terminal rises, and an avalanche current flows through the first switching element. This causes the junction temperature of the first switching element to rise, leading to a second breakdown. As the second breakdown voltage rises, the inter-terminal voltage rises, and before the junction temperature of the first switching element reaches 300°C, the inter-terminal voltage reaches the first breakdown voltage of the first diode element, causing the first diode element to break down. Then, as the first diode element breaks down, an avalanche current also begins to flow through the first diode element, correspondingly reducing the avalanche current flowing through the first switching element. Therefore, compared to when current flows only through the first switching element, diverting some of the current to the first diode element reduces heat generation in the first switching element. Therefore, the junction temperature of the first switching element is less likely to reach the breakdown temperature, and the avalanche resistance can be improved.

[0014] [2] In [1], the second breakdown voltage may include a fifth breakdown voltage when the junction temperature is 250° C., and the first breakdown voltage within a junction temperature range of 50° C. to 70° C. may be between the third breakdown voltage and the fifth breakdown voltage. In this case, the inter-terminal voltage reaches the first breakdown voltage of the first diode element before the junction temperature of the first switching element reaches 250° C., causing the first diode element to break down.

[0015] [3] In [1], the second breakdown voltage may include a sixth breakdown voltage when the junction temperature is 175° C., and the first breakdown voltage within a junction temperature range of 50° C. to 70° C. may be between the third breakdown voltage and the sixth breakdown voltage. In this case, the voltage between the terminals reaches the first breakdown voltage of the first diode element before the junction temperature of the first switching element reaches 175° C., causing the first diode element to break down.

[0016] [4] Another aspect of the present disclosure provides a semiconductor device including a first terminal, a second terminal, a first diode element connected between the first terminal and the second terminal and having a first breakdown voltage that is dependent on ambient temperature, and a first switching element connected in parallel to the first diode element between the first terminal and the second terminal and having a second breakdown voltage that is dependent on ambient temperature, wherein the second breakdown voltage within an ambient temperature range of 50° C. to 70° C. is lower than the first breakdown voltage within an ambient temperature range of 50° C. to 70° C., the second breakdown voltage includes a third breakdown voltage at an ambient temperature of 50° C. and a fourth breakdown voltage at an ambient temperature of 300° C., and the first breakdown voltage within an ambient temperature range of 50° C. to 70° C. is between the third breakdown voltage and the fourth breakdown voltage. As with the semiconductor device described in [1], the junction temperature of the first switching element is less likely to reach a breakdown temperature, thereby improving avalanche resistance.

[0017] [5] In [4], the second breakdown voltage may have a fifth breakdown voltage when the ambient temperature is 250° C., and the first breakdown voltage within an ambient temperature range of 50° C. to 70° C. may be between the third breakdown voltage and the fifth breakdown voltage. In this case, the voltage between the terminals of the first switching element reaches the first breakdown voltage of the first diode element before the ambient temperature of the first switching element reaches 250° C., causing the first diode element to break down.

[0018] [6] In [4], the second breakdown voltage may include a sixth breakdown voltage when the ambient temperature is 175° C., and the first breakdown voltage within an ambient temperature range of 50° C. to 70° C. may be between the third breakdown voltage and the sixth breakdown voltage. In this case, the voltage between the terminals of the first switching element reaches the first breakdown voltage of the first diode element before the ambient temperature of the first switching element reaches 175° C., causing the first diode element to break down.

[0019] [7] Another aspect of the present disclosure provides a semiconductor device comprising: a first terminal; a second terminal; a first diode element connected between the first terminal and the second terminal, the first diode element having a first breakdown voltage that is junction temperature dependent; and a first switching element connected in parallel to the first diode element between the first terminal and the second terminal, the first breakdown voltage being junction temperature dependent. The second breakdown voltage within a junction temperature range of 50°C to 70°C is lower than the first breakdown voltage within a junction temperature range of 50°C to 70°C. When a dynamic avalanche state is entered, an avalanche current flows through the first switching element. The avalanche current increases the junction temperature of the first switching element. The increase in the junction temperature of the first switching element increases a terminal-to-terminal voltage between the first terminal and the second terminal. The increased terminal voltage reaches the first breakdown voltage of the first diode element, causing the avalanche current to flow through the first diode element before the first switching element is broken down.

[0020] In this semiconductor device, when the device transitions to a dynamic avalanche state, an avalanche current flows through the first switching element, and then, before the first switching element is destroyed, the avalanche current flows through the first diode element. Therefore, since the avalanche current flows through the first switching element and the first diode element, the avalanche resistance can be improved.

[0021] [8] Another aspect of the present disclosure provides a semiconductor device comprising: a first terminal; a second terminal; a first diode element connected between the first terminal and the second terminal, the first diode element having a first breakdown voltage that is dependent on ambient temperature; and a first switching element connected in parallel to the first diode element between the first terminal and the second terminal, the first breakdown voltage being dependent on ambient temperature, wherein the second breakdown voltage within an ambient temperature range of 50°C to 70°C is lower than the first breakdown voltage within an ambient temperature range of 50°C to 70°C, and when the semiconductor device transitions to a dynamic avalanche state, an avalanche current flows through the first switching element, the avalanche current increases a junction temperature of the first switching element, the increase in the junction temperature of the first switching element increases a terminal-to-terminal voltage between the first terminal and the second terminal, and the increase in the terminal-to-terminal voltage reaches the first breakdown voltage of the first diode element, causing the avalanche current to flow through the first diode element before the first switching element is broken. As with the semiconductor device described in [7], the avalanche resistance can be improved.

[0022] [9] In any of [1] to [6], when transitioning to a dynamic avalanche state occurs, an avalanche current may flow through the first switching element, the flow of the avalanche current may increase a junction temperature of the first switching element, the increase in the junction temperature of the first switching element may increase a terminal voltage between the first terminal and the second terminal, the increase in the terminal voltage may reach the first breakdown voltage of the first diode element, and an avalanche current may flow through the first diode element before the first switching element is destroyed. In this case, when transitioning to a dynamic avalanche state occurs, an avalanche current may flow through the first switching element, and then an avalanche current may flow through the first diode element before the first switching element is destroyed.

[0023]

[10] In any of [1] to [9], a plurality of pairs of the first switching element and the first diode element may be connected in parallel between the first terminal and the second terminal, allowing a larger current to flow.

[0024]

[11] In any of [1] to

[10] , the first switching element may be a field-effect transistor made of silicon carbide, and the first diode element may be a Schottky barrier diode made of silicon carbide. Generally, by using a field-effect transistor made of silicon carbide, high-speed operation can be achieved while maintaining a high breakdown voltage. On the other hand, surge voltages caused by high-speed current displacement increase, increasing the possibility of transitioning to an avalanche state. In this semiconductor device, the avalanche resistance can be improved, so that the first switching element can achieve high breakdown voltage and high-speed operation, while preventing damage to the first switching element even when transitioning to an avalanche state.

[0025] Generally, in a switching element, when the on-resistance is lowered, the breakdown voltage also tends to decrease, and it is not easy to obtain a high breakdown voltage while obtaining a low on-resistance. In this semiconductor device, good avalanche resistance is obtained even if the breakdown voltage of the first switching element is not particularly high, so a structure that obtains a low on-resistance can be adopted for the first switching element.

[0026]

[12] In any of [1] to

[11] , the semiconductor device may further include a third terminal, a second diode element connected between the third terminal and the second terminal and having a seventh breakdown voltage that is junction temperature dependent, and a second switching element connected in parallel to the second diode element between the third terminal and the second terminal and having an eighth breakdown voltage that is junction temperature dependent, wherein the eighth breakdown voltage within a junction temperature range of 50°C to 70°C is lower than the seventh breakdown voltage within a junction temperature range of 50°C to 70°C, the eighth breakdown voltage may include a ninth breakdown voltage when the junction temperature is 50°C and a tenth breakdown voltage when the junction temperature is 300°C, and the seventh breakdown voltage within a junction temperature range of 50°C to 70°C may be between the ninth breakdown voltage and the tenth breakdown voltage. In this case, two arms connected in series between the first terminal and the third terminal may be configured.

[0027]

[13] In

[12] , the eighth breakdown voltage may include an eleventh breakdown voltage when the junction temperature is 250° C., and the seventh breakdown voltage within a junction temperature range of 50° C. to 70° C. may be between the ninth breakdown voltage and the eleventh breakdown voltage. In this case, the voltage between the terminals reaches the seventh breakdown voltage of the second diode element before the junction temperature of the second switching element reaches 250° C., causing the second diode element to break down.

[0028]

[14] In

[12] , the eighth breakdown voltage may include a twelfth breakdown voltage when the junction temperature is 175°C, and the seventh breakdown voltage within a junction temperature range of 50°C to 70°C may be between the ninth breakdown voltage and the twelfth breakdown voltage. In this case, the voltage between the terminals reaches the seventh breakdown voltage of the second diode element before the junction temperature of the second switching element reaches 175°C, causing the second diode element to break down.

[0029]

[15] In any of [1] to

[11] , the power supply may further include a third terminal, a second diode element connected between the third terminal and the second terminal and having a seventh breakdown voltage that is dependent on ambient temperature, and a second switching element connected in parallel to the second diode element between the third terminal and the second terminal and having an eighth breakdown voltage that is dependent on ambient temperature, wherein the eighth breakdown voltage within an ambient temperature range of 50°C to 70°C is lower than the seventh breakdown voltage within an ambient temperature range of 50°C to 70°C, the eighth breakdown voltage may include a ninth breakdown voltage when the ambient temperature is 50°C and a tenth breakdown voltage when the ambient temperature is 300°C, and the seventh breakdown voltage within an ambient temperature range of 50°C to 70°C may be between the ninth breakdown voltage and the tenth breakdown voltage. In this case, two arms connected in series can be configured between the first terminal and the third terminal.

[0030]

[16] In

[15] , the eighth breakdown voltage may include an eleventh breakdown voltage when the ambient temperature is 250° C., and the seventh breakdown voltage within an ambient temperature range of 50° C. to 70° C. may be between the ninth breakdown voltage and the eleventh breakdown voltage. In this case, the voltage between the terminals of the second switching element reaches the seventh breakdown voltage of the second diode element, causing the second diode element to break down, before the ambient temperature of the second switching element reaches 250° C.

[0031]

[17] In

[15] , the eighth breakdown voltage may include a twelfth breakdown voltage when the ambient temperature is 175° C., and the seventh breakdown voltage within an ambient temperature range of 50° C. to 70° C. may be between the ninth breakdown voltage and the twelfth breakdown voltage. In this case, the voltage between the terminals of the second switching element reaches the seventh breakdown voltage of the second diode element, causing the second diode element to break down, before the ambient temperature of the second switching element reaches 175° C.

[0032]

[18] In any of [1] to

[11] , the semiconductor device may further include a third terminal, a second diode element connected between the third terminal and the second terminal and having a seventh breakdown voltage that is junction temperature dependent, and a second switching element connected in parallel to the second diode element between the third terminal and the second terminal and having an eighth breakdown voltage that is junction temperature dependent, wherein the eighth breakdown voltage within a junction temperature range of 50°C to 70°C is lower than the seventh breakdown voltage within a junction temperature range of 50°C to 70°C, and when transitioning to a dynamic avalanche state, an avalanche current flows through the second switching element, the flow of the avalanche current increases the junction temperature of the second switching element, the increase in the junction temperature of the second switching element increases a terminal voltage between the third terminal and the second terminal, and the increase in the terminal voltage reaches the seventh breakdown voltage of the second diode element, causing an avalanche current to flow through the second diode element before the second switching element is broken. In this case, two arms connected in series can be configured between the first terminal and the third terminal.

[0033]

[19] In any of [1] to

[11] , the semiconductor device may further include a third terminal, a second diode element connected between the third terminal and the second terminal and having a seventh breakdown voltage that is dependent on environmental temperature, and a second switching element connected in parallel to the second diode element between the third terminal and the second terminal and having an eighth breakdown voltage that is dependent on environmental temperature, wherein the eighth breakdown voltage within an environmental temperature range of 50°C to 70°C is lower than the seventh breakdown voltage within an environmental temperature range of 50°C to 70°C, and when transitioning to a dynamic avalanche state, an avalanche current flows through the second switching element, and the flow of the avalanche current increases a junction temperature of the second switching element, and the increase in the junction temperature of the second switching element increases a terminal voltage between the third terminal and the second terminal, and the increase in the terminal voltage reaches the seventh breakdown voltage of the second diode element, so that an avalanche current flows through the second diode element before the second switching element is broken. In this case, two arms connected in series can be configured between the first terminal and the third terminal.

[0034]

[20] In any of

[12] to

[17] , when transitioning to a dynamic avalanche state, an avalanche current may flow through the second switching element, the flow of the avalanche current increases the junction temperature of the second switching element, the increase in the junction temperature of the second switching element increases the inter-terminal voltage between the third terminal and the second terminal, and the increase in the inter-terminal voltage may reach the seventh breakdown voltage of the second diode element, causing an avalanche current to flow through the second diode element before the second switching element breaks down. In this case, when transitioning to a dynamic avalanche state occurs, an avalanche current flows through the second switching element, and then an avalanche current flows through the second diode element before the second switching element breaks down.

[0035]

[21] In any of

[12] to

[20] , a plurality of pairs of the second switching element and the second diode element may be connected in parallel between the third terminal and the second terminal, allowing a larger current to flow.

[0036]

[22] In any of

[12] to

[21] , the second switching element may be a field-effect transistor made of silicon carbide, and the second diode element may be a Schottky barrier diode made of silicon carbide. In this semiconductor device, avalanche resistance can be improved, so that the second switching element can achieve high breakdown voltage and high-speed operation, and breakdown of the second switching element can be suppressed even when the semiconductor device transitions to an avalanche state.

[0037] [Details of the embodiments of the present disclosure] Hereinafter, embodiments of the present disclosure will be described in detail, but the present disclosure is not limited to these. In this specification and drawings, components having substantially the same functional configurations may be designated by the same reference numerals to avoid redundant description.

[0038] FIG. 1 is a perspective view showing a semiconductor device according to an embodiment. FIG. 2 is a top view showing the semiconductor device according to an embodiment. However, in FIG. 2, the case is seen through. FIG. 3 is a cross-sectional view showing the relationship between a heat sink, a first insulating substrate, and a second insulating substrate in the semiconductor device according to an embodiment. FIG. 3 corresponds to a cross-sectional view taken along line III-III in FIG. 2.

[0039] The semiconductor device 1 according to the embodiment mainly includes a heat sink 2, a case 9, a P terminal 3, an N terminal 4, a first O terminal 5, and a second O terminal 6. Hereinafter, the first O terminal 5 and the second O terminal 6 may be collectively referred to as O terminals. The P terminal 3 is a positive power supply terminal, the N terminal 4 is a negative power supply terminal, and the first O terminal 5 and the second O terminal 6 are output terminals. The P terminal 3, the N terminal 4, the first O terminal 5, and the second O terminal 6 are assembled to the case 9. The case 9 also has assembled thereto a first gate terminal 131, a first sense source terminal 132, a sense drain terminal 133, a second gate terminal 231, a second sense source terminal 232, a first thermistor terminal 331, and a second thermistor terminal 332. The P terminal 3 and the N terminal 4 are examples of first or third terminals, and the first O terminal 5 and the second O terminal 6 are examples of second terminals.

[0040] In this disclosure, the X1-X2 direction, the Y1-Y2 direction, and the Z1-Z2 direction are defined as mutually orthogonal directions. The plane including the X1-X2 direction and the Y1-Y2 direction is defined as the XY plane, the plane including the Y1-Y2 direction and the Z1-Z2 direction is defined as the YZ plane, and the plane including the Z1-Z2 direction and the X1-X2 direction is defined as the ZX plane. For convenience, the Z1 direction is defined as the upward direction, and the Z2 direction is defined as the downward direction. In this disclosure, a planar view refers to viewing an object from the Z1 side. The X1-X2 direction is the direction along the long sides of the rectangular heat sink 2 and case 9 in a planar view, the Y1-Y2 direction is the direction along the short sides of the heat sink 2 and case 9, and the Z1-Z2 direction is the direction along the normal to the heat sink 2 and case 9.

[0041] The heat sink 2 is, for example, a rectangular plate-like body with a uniform thickness in a plan view. The heat sink 2 has a first main surface 2A and a second main surface 2B opposite to the first main surface 2A. The material of the heat sink 2 is a metal with high thermal conductivity, such as copper (Cu), a copper alloy, or aluminum (Al). The heat sink 2 is fixed to a cooler or the like using a thermal interface material (TIM) or the like.

[0042] The case 9 is formed, for example, in a frame shape when viewed from above, and the outer shape of the case 9 is the same as the outer shape of the heat sink 2. The case 9 is made of an insulating material such as resin. The case 9 has a pair of side walls 91 and 92 facing each other and a pair of end walls 93 and 94 connecting both ends of the side walls 91 and 92. The side walls 91 and 92 are arranged parallel to the ZX plane, and the end walls 93 and 94 are arranged parallel to the YZ plane. The side wall 92 is arranged on the Y2 side of the side wall 91, and the end wall 94 is arranged on the X2 side of the end wall 93. The case 9 has a terminal block 95 protruding from the end wall 93 in the X1 direction and a terminal block 96 protruding from the end wall 94 in the X2 direction.

[0043] The P terminal 3 and the N terminal 4 are arranged on the upper surface (surface on the Z1 side) of the terminal block 95, and the first O terminal 5 and the second O terminal 6 are arranged on the upper surface (surface on the Z1 side) of the terminal block 96. For example, the N terminal 4 is arranged on the Y2 side of the P terminal 3, and the second O terminal 6 is arranged on the Y2 side of the first O terminal 5. The P terminal 3, the N terminal 4, the first O terminal 5, and the second O terminal 6 are made of metal plates. One end of each of the P terminal 3 and the N terminal 4 is exposed on the X2 side of the end wall portion 93, and the other end is extended to the upper surface of the terminal block 95. One end of each of the first O terminal 5 and the second O terminal 6 is exposed on the X1 side of the end wall portion 94, and the other end is extended to the upper surface of the terminal block 96.

[0044] A first gate terminal 131, a first sense source terminal 132, a sense drain terminal 133, a first thermistor terminal 331, and a second thermistor terminal 332 are attached to the side wall portion 91. One end of each of the first gate terminal 131, the first sense source terminal 132, the sense drain terminal 133, the first thermistor terminal 331, and the second thermistor terminal 332 is exposed on the Y2 side of the side wall portion 91, and the other end of each protrudes from the upper surface (surface on the Z1 side) of the side wall portion 91 to the outside (Z1 side) of the case 9. The sense drain terminal 133 is located near the end of the X2 side of the side wall portion 91. The first thermistor terminal 331 and the second thermistor terminal 332 are located near the end of the X1 side of the side wall portion 91. For example, the second thermistor terminal 332 is located on the X1 side of the first thermistor terminal 331. The first gate terminal 131 and the first sense source terminal 132 are disposed near the center of the side wall portion 91 in the X1-X2 direction and on the X2 side of the center in the X1-X2 direction. For example, the first sense source terminal 132 is disposed on the X2 side of the first gate terminal 131.

[0045] A second gate terminal 231 and a second sense source terminal 232 are attached to the side wall portion 92. One end of each of the second gate terminal 231 and the second sense source terminal 232 is exposed on the Y1 side of the side wall portion 92, and the other end of each protrudes from the upper surface (surface on the Z1 side) of the side wall portion 92 to the outside (Z1 side) of the case 9. The second gate terminal 231 and the second sense source terminal 232 are arranged near the center of the side wall portion 92 in the X1-X2 direction and on the X1 side of the center in the X1-X2 direction. For example, the second sense source terminal 232 is arranged on the X1 side of the second gate terminal 231.

[0046] A first insulating substrate 10 and a second insulating substrate 20 are arranged on the Z1 side of the heat sink 2. That is, the first insulating substrate 10 and the second insulating substrate 20 are arranged on the first main surface 2A of the heat sink 2. For example, the second insulating substrate 20 is arranged on the X1 side of the first insulating substrate 10.

[0047] The first insulating substrate 10 has conductive layers 11, 12, 13, 14, and 18 on its Z1 side surface and a conductive layer 19 on its Z2 side surface. The conductive layer 19 is joined to the heat sink 2 with a bonding material 7 such as solder. A plurality of first transistors 110, for example, four, are mounted on the conductive layer 13. The four first transistors 110 are aligned in the X1-X2 direction. A first transistor group 110A is composed of the four first transistors 110. A plurality of second diodes 220, for example, eight, are mounted on the conductive layer 12. The eight second diodes 220 are aligned in two rows of four in the X1-X2 direction. A second diode group 220A is composed of the eight second diodes 220. In this embodiment, the second conductor and the seventh conductor are integrated into the conductive layer 12. As a modification, the conductive layer constituting the second conductor and the conductive layer constituting the seventh conductor may be separate conductive layers that are connected together. In other words, the present disclosure is not limited to a configuration in which the second conductor and the seventh conductor are integrated into conductive layer 12.

[0048] The second insulating substrate 20 has conductive layers 21, 22, 23, 24, 25, 26, 27, and 28 on its Z1-side surface and a conductive layer 29 on its Z2-side surface. The conductive layer 29 is joined to the heat sink 2 with a bonding material 8 such as solder. A plurality of second transistors 210, for example, four, are mounted on the conductive layer 23. The four second transistors 210 are aligned in the X1-X2 direction. A second transistor group 210A is composed of the four second transistors 210. A plurality of first diodes 120, for example, eight, are mounted on the conductive layer 25. The eight first diodes 120 are aligned in two rows of four in the X1-X2 direction. A first diode group 120A is composed of the eight first diodes 120.

[0049] Here, the first transistor 110, the first diode 120, the second transistor 210, and the second diode 220 will be described. Fig. 4 is a cross-sectional view showing the first transistor. Fig. 5 is a cross-sectional view showing the first diode. Fig. 6 is a cross-sectional view showing the second transistor. Fig. 7 is a cross-sectional view showing the second diode.

[0050] 4, the first transistor 110 has a first gate electrode 111, a first source electrode 112, and a first drain electrode 113. The first gate electrode 111 and the first source electrode 112 are arranged on the main surface of the first transistor 110 on the Z1 side, and the first drain electrode 113 is arranged on the main surface of the first transistor 110 on the Z2 side. The first drain electrode 113 is joined to the conductive layer 13 by a joining material (not shown) such as solder. The first transistor 110 is an example of a first switching element or a second switching element.

[0051] 5, the first diode 120 has a first anode electrode 121 and a first cathode electrode 122. The first anode electrode 121 is disposed on the Z1-side principal surface of the first diode 120, and the first cathode electrode 122 is disposed on the Z2-side principal surface of the first diode 120. The first cathode electrode 122 is bonded to the conductive layer 25 by a bonding material (not shown) such as solder. The first diode 120 is an example of a first diode element or a second diode element.

[0052] 6, the second transistor 210 has a second gate electrode 211, a second source electrode 212, and a second drain electrode 213. The second gate electrode 211 and the second source electrode 212 are arranged on the main surface of the second transistor 210 on the Z1 side, and the second drain electrode 213 is arranged on the main surface of the second transistor 210 on the Z2 side. The second drain electrode 213 is joined to the conductive layer 23 by a joining material (not shown) such as solder. The second transistor 210 is an example of a first switching element or a second switching element.

[0053] 7, the second diode 220 has a second anode electrode 221 and a second cathode electrode 222. The second anode electrode 221 is disposed on the Z1-side principal surface of the second diode 220, and the second cathode electrode 222 is disposed on the Z2-side principal surface of the second diode 220. The second cathode electrode 222 is bonded to the conductive layer 12 by a bonding material (not shown) such as solder. The second diode 220 is an example of a first diode element or a second diode element.

[0054] The semiconductor device 1 has a plurality of wires 31, a plurality of wires 32, a plurality of wires 41, and a plurality of wires 42. The wires 31 connect the conductive layer 13 provided on the first insulating substrate 10 to the conductive layer 25 provided on the second insulating substrate 20. The wires 32 connect the conductive layer 12 provided on the first insulating substrate 10 to the conductive layer 24 provided on the second insulating substrate 20. The wires 41 connect the conductive layer 12 provided on the first insulating substrate 10 to the conductive layer 23 provided on the second insulating substrate 20. The wires 42 connect the conductive layer 14 provided on the first insulating substrate 10 to the conductive layer 22 provided on the second insulating substrate 20.

[0055] The semiconductor device 1 has a plurality of wires 51, a plurality of wires 52, a plurality of wires 53, a plurality of wires 54, and a plurality of wires 55. The wires 51 connect first gate electrodes 111 provided on each of the four first transistors 110 to a conductive layer 11 provided on the first insulating substrate 10. The wires 52 connect first source electrodes 112 provided on each of the four first transistors 110 to a conductive layer 12 provided on the first insulating substrate 10. The wires 53 connect first sense source electrodes (not shown) provided on each of the four first transistors 110 to a conductive layer 18 provided on the first insulating substrate 10. The wires 54 connect second anode electrodes 221 provided on four of the eight second diodes 220 arranged on the Y1 side to a conductive layer 14 provided on the first insulating substrate 10. The wire 55 connects the second anode electrodes 221 provided on the four second diodes 220 arranged on the Y1 side out of the eight second diodes 220 to the second anode electrodes 221 provided on the four second diodes 220 arranged on the Y2 side.

[0056] The semiconductor device 1 has a wire 61, a plurality of wires 62, a plurality of wires 63, a wire 64, and a wire 65. The wire 61 connects the conductive layer 11 provided on the first insulating substrate 10 to the first gate terminal 131. The wire 62 connects the conductive layer 12 provided on the first insulating substrate 10 to the first O terminal 5. The wire 63 connects the conductive layer 12 provided on the first insulating substrate 10 to the second O terminal 6. The wire 64 connects the conductive layer 13 provided on the first insulating substrate 10 to the sense drain terminal 133. The wire 65 connects the conductive layer 18 provided on the first insulating substrate 10 to the first sense source terminal 132.

[0057] The semiconductor device 1 has a plurality of wires 71, a plurality of wires 72, a plurality of wires 73, a plurality of wires 74, and a plurality of wires 75. The wire 71 connects a second gate electrode 211 provided on each of the four second transistors 210 to a conductive layer 21 provided on the second insulating substrate 20. The wire 72 connects a second source electrode 212 provided on each of the four second transistors 210 to a conductive layer 22 provided on the second insulating substrate 20. The wire 73 connects a second sense source electrode (not shown) provided on each of the four second transistors 210 to a conductive layer 28 provided on the second insulating substrate 20. The wire 74 connects a first anode electrode 121 provided on each of four first diodes 120 arranged on the Y2 side of the eight first diodes 120 to a conductive layer 24 provided on the second insulating substrate 20. The wire 75 connects the first anode electrodes 121 provided on the four first diodes 120 arranged on the Y2 side out of the eight first diodes 120 to the first anode electrodes 121 provided on the four first diodes 120 arranged on the Y1 side.

[0058] The semiconductor device 1 includes a wire 81, a plurality of wires 82, a plurality of wires 83, a wire 85, a wire 86, and a wire 87. The wire 81 connects a conductive layer 21 provided on the second insulating substrate 20 to a second gate terminal 231. The wire 82 connects a conductive layer 22 provided on the second insulating substrate 20 to an N-terminal 4. The wire 83 connects a conductive layer 25 provided on the second insulating substrate 20 to a P-terminal 3. The wire 85 connects a conductive layer 28 provided on the second insulating substrate 20 to a second sense-source terminal 232. The wire 86 connects a conductive layer 26 provided on the second insulating substrate 20 to a first thermistor terminal 331. The wire 87 connects a conductive layer 27 provided on the second insulating substrate 20 to a second thermistor terminal 332. The semiconductor device 1 includes a thermistor 330 connected to the conductive layer 26 and the conductive layer 27 .

[0059] Here, the circuit configuration of the semiconductor device 1 according to the embodiment will be described. Fig. 8 is a circuit diagram showing the semiconductor device according to the embodiment.

[0060] A first cathode electrode 122 of the first diode 120 is connected to the P terminal 3 via a wire 83 and a conductive layer 25. A first drain electrode 113 of the first transistor 110 is connected to the P terminal 3 via a wire 83, a conductive layer 25, a wire 31, and a conductive layer 13. The conductive layer 12 is connected to the first O terminal 5 via a wire 62 and to the second O terminal 6 via a wire 63. A first source electrode 112 of the first transistor 110 is connected to the conductive layer 12 via a wire 52. A first anode electrode 121 of the first diode is connected to the conductive layer 12 via a wire 32, a conductive layer 24, and wires 74 and 75.

[0061] A first gate electrode 111 of the first transistor 110 is connected to a first gate terminal 131 via a wire 61, a conductive layer 11, and a wire 51. A first sense source electrode of the first transistor 110 is connected to a first sense source terminal 132 via a wire 65, a conductive layer 18, and a wire 53. A first drain electrode 113 of the first transistor 110 is connected to a sense drain terminal 133 via a wire 64 and a conductive layer 13.

[0062] A second source electrode 212 of the second transistor 210 is connected to the N terminal 4 via a wire 82, a conductive layer 22, and a wire 72. A second anode electrode 221 of the second diode 220 is connected to the N terminal 4 via a wire 82, a conductive layer 22, a wire 42, and wires 54 and 55. A second cathode electrode 222 of the second transistor 210 is connected to the conductive layer 12. A second drain electrode 213 of the second transistor 210 is connected to the conductive layer 12 via a wire 41 and a conductive layer 23.

[0063] A second gate electrode 211 of the second transistor 210 is connected to a second gate terminal 231 via a wire 81, a conductive layer 21, and a wire 71. A second sense source electrode of the second transistor 210 is connected to a second sense source terminal 232 via a wire 85, a conductive layer 28, and a wire 73. One electrode of the thermistor 330 is connected to a first thermistor terminal 331 via a wire 86 and a conductive layer 26. The other electrode of the thermistor 330 is connected to a second thermistor terminal 332 via a wire 87 and a conductive layer 27.

[0064] 8, the first drain electrode 113 of the first transistor 110 and the first cathode electrode 122 of the first diode 120 are commonly connected to the P terminal 3, and the first source electrode 112 and the first anode electrode 121 are commonly connected to the first O terminal 5 and the second O terminal 6. In other words, the first transistor 110 and the first diode 120 are connected in parallel between the P terminal 3 and the first O terminal 5 and the second O terminal 6. As shown in FIGS. 1 and 2, a plurality of pairs of the first transistor 110 and the first diode 120 are connected in parallel between the P terminal 3 and the first O terminal 5 and the second O terminal 6.

[0065] Furthermore, the second drain electrode 213 of the second transistor 210 and the second cathode electrode 222 of the second diode 220 are commonly connected to the first O terminal 5 and the second O terminal 6, and the second source electrode 212 and the second anode electrode 221 are commonly connected to the N terminal 4. That is, the second transistor 210 and the second diode 220 are connected in parallel between the N terminal 4 and the first O terminal 5 and the second O terminal 6. As shown in FIGS. 1 and 2 , multiple pairs of the second transistor 210 and the second diode 220 are connected in parallel between the N terminal 4 and the first O terminal 5 and the second O terminal 6.

[0066] The upper arm 100 includes a first transistor 110 (first transistor group 110A) and a first diode 120 (first diode group 120A). The lower arm 200 includes a second transistor 210 (second transistor group 210A) and a second diode 220 (second diode group 220A). The upper arm 100 and the lower arm 200 are connected in series between a P terminal 3 and an N terminal 4. The upper arm 100 may include the P terminal 3 and an O terminal, and the lower arm 200 may include the N terminal and an O terminal.

[0067] The plurality of first transistors 110 included in the upper arm 100 may be provided only on the first insulating substrate 10, and the plurality of first diodes 120 included in the upper arm 100 may be provided only on the second insulating substrate 20. Alternatively, the plurality of second transistors 210 included in the lower arm 200 may be provided only on the second insulating substrate 20, and the plurality of second diodes 220 included in the lower arm 200 may be provided only on the first insulating substrate 10.

[0068] Next, the operation of the semiconductor device 1 according to the embodiment will be described. Figures 9 to 12 are schematic diagrams showing the operation of the semiconductor device according to the embodiment.

[0069] 9 shows the path of current I1 flowing from the P terminal 3 to the first O terminal 5 and the second O terminal 6. As shown in FIG. 9, current I1 flows from the P terminal 3 to the first O terminal 5 and the second O terminal 6 via wire 83, conductive layer 25, wire 31, conductive layer 13, first transistor group 110A, wire 52, conductive layer 12, and wires 62 and 63.

[0070] 10 shows the path of current I2 flowing from the first O terminal 5 and the second O terminal 6 to the P terminal 3. As shown in Fig. 10, current I2 flows from the first O terminal 5 and the second O terminal 6 to the P terminal 3 via wires 62 and 63, conductive layer 12, wire 32, conductive layer 24, wires 74 and 75, first diode group 120A, conductive layer 25, and wire 83.

[0071] In this way, the current I1 flowing from the P terminal 3 to the first O terminal 5 and the second O terminal 6 flows through the wire 31 but does not flow through the wire 32. On the other hand, the current I2 flowing from the first O terminal 5 and the second O terminal 6 to the P terminal 3 flows through the wire 32 but does not flow through the wire 31.

[0072] 11 shows the path of current I3 flowing from the N terminal 4 to the first O terminal 5 and the second O terminal 6. As shown in Fig. 11, current I3 flows from the N terminal 4 to the first O terminal 5 and the second O terminal 6 via wire 82, conductive layer 22, wire 72, second transistor group 210A, conductive layer 23, wire 41, conductive layer 12, and wires 62 and 63.

[0073] 12 shows the path of current I4 flowing from the first O terminal 5 and the second O terminal 6 to the N terminal 4. As shown in Fig. 12, current I4 flows from the first O terminal 5 and the second O terminal 6 to the N terminal 4 via wires 62 and 63, conductive layer 12, second diode group 220A, wires 54 and 55, conductive layer 14, wire 42, conductive layer 22, and wire 82.

[0074] In this way, the current I3 flowing from the N terminal 4 to the first O terminal 5 and the second O terminal 6 flows through the wire 41 but does not flow through the wire 42. On the other hand, the current I4 flowing from the first O terminal 5 and the second O terminal 6 to the N terminal 4 flows through the wire 42 but does not flow through the wire 41.

[0075] In the semiconductor device 1 according to the embodiment, the upper arm 100 includes a first transistor 110 and a first diode 120, the first transistor 110 being provided on the first insulating substrate 10, and the first diode 120 being provided on the second insulating substrate 20. Therefore, the current I1 flowing from the P terminal 3 to the first O terminal 5 and the second O terminal 6 and the current I2 flowing from the first O terminal 5 and the second O terminal 6 to the P terminal 3 pass through different wires 31 and 32. Therefore, the amount of heat generated in the wires 31 and 32 can be reduced compared to when the currents flowing between the first insulating substrate 10 and the second insulating substrate 20 pass through the same connecting member.

[0076] Similarly, lower arm 200 includes second transistor 210 and second diode 220, with second transistor 210 provided on second insulating substrate 20 and second diode 220 provided on first insulating substrate 10. Therefore, current I3 flowing from N terminal 4 to first O terminal 5 and second O terminal 6 and current I4 flowing from first O terminal 5 and second O terminal 6 to N terminal 4 pass through different wires 41 and 42. Therefore, the amount of heat generated in wires 41 and 42 can be reduced compared to when currents flowing between first insulating substrate 10 and second insulating substrate 20 pass through the same connecting member.

[0077] By reducing the amount of heat generated in this manner, it is possible to suppress the risk of the heat generated by the connecting member and the wire becoming excessive, and to reduce the risk of the wire melting.

[0078] The semiconductor device 1 transitions to a dynamic avalanche state when, for example, a surge voltage becomes excessive. An excessive surge voltage may occur at turn-off. In addition, when a short-circuit fault due to a load failure or the like causes a short-circuit current to flow through the first transistor 110 or the second transistor 210, the surge voltage may become excessive when the protection circuit interrupts the current.

[0079] In this embodiment, the first transistor 110, the second transistor 210, the first diode 120, and the second diode 220 have the following characteristics, so that excellent avalanche resistance is obtained.

[0080] Here, the breakdown voltages of the first transistor 110, the second transistor 210, the first diode 120, and the second diode 220 will be described. Fig. 13 is a diagram showing an example of the characteristics of the first transistor 110, the second transistor 210, the first diode 120, and the second diode 220. The horizontal axis in Fig. 13 represents the junction temperature T j 13, the solid line represents the characteristics of the first diode 120 and the second diode 220, and the two-dot chain line represents the characteristics of the first transistor 110 and the second transistor 210.

[0081] As shown in FIG. 13, the first diode 120 and the second diode 220 have a breakdown voltage BV1 that is dependent on the junction temperature. The breakdown voltage BV1 increases as the junction temperature increases. Generally, in an avalanche breakdown state, electrons are accelerated to high speed within a semiconductor and collide with atoms, generating more electrons like an avalanche. Furthermore, the higher the junction temperature, the greater the lattice vibration within the semiconductor, suppressing the acceleration of electrons. Therefore, the higher the junction temperature, the less likely avalanche breakdown occurs, and the higher the breakdown voltage. The breakdown voltage BV1 is an example of the first breakdown voltage or the seventh breakdown voltage.

[0082] Transistor junction temperature T j The breakdown voltage in can be determined by the following two methods. Here, the breakdown voltage is defined as the voltage when the current value reaches 1 mA.

[0083] In the first method, the wires of the transistor to be measured in the semiconductor device are cut or the like, and the transistor is isolated from other transistors and diodes in the circuit when the breakdown voltage is measured as described below. The transistor itself is placed in a thermostatic chamber, or the semiconductor device including the transistor is placed in a thermostatic chamber, and the temperature of the thermostatic chamber is set to the junction temperature T j Temperature T equals s Then, the temperature of the thermostatic bath is set to T s The breakdown voltage is measured in a stable state at 1000 kJ / s. A semiconductor device analyzer (model number: BA1500A) from Keysight Technologies can be used to measure the breakdown voltage.

[0084] In the second method, the temperature T of the case 9 at the part where the thermistor 330 is installed is calculated based on the output signals from the first thermistor terminal 331 and the second thermistor terminal 332 connected to the thermistor 330. cThen, the generated loss, which can be calculated from the current and voltage values ​​flowing through each transistor and other element, i.e., the heat generation P, and the thermal resistance R, which can be read from the design value or data sheet, are measured. th(j-c) and the temperature change ΔT of each transistor and other elements j That is, calculate the heat generation P and thermal resistance R th(j-c) From the product of these, the temperature change ΔT of each transistor and other element is j By using these data and conducting simulations and other analyses, the junction temperature T j Identify.

[0085] As a modification of the second method, the temperature T of the case 9 is measured by using a thermocouple to measure the temperature of the rear surface of the heat sink 2. c In this case, the loss that occurs can be calculated from the current and voltage values ​​flowing through each element such as a transistor, that is, the heat generation P, and the thermal resistance R that can be read from the design value or data sheet. th(j-c) Using the temperature change ΔT of each transistor and other elements j That is, calculate the heat generation P and thermal resistance R th(j-c) From the product of these, the temperature change ΔT of each transistor and other element is j By using these data and conducting simulations and other analyses, the junction temperature T j Identify.

[0086] In the second method, the breakdown voltage can also be measured using a Keysight Technologies Semiconductor Device Analyzer (model number: BA1500A).

[0087] 13, the first transistor 110 and the second transistor 210 have a breakdown voltage BV2 that is dependent on the junction temperature. The breakdown voltage BV2 increases as the junction temperature increases. The breakdown voltage BV2 includes a breakdown voltage BVDSS3 when the junction temperature is 50°C and a breakdown voltage BVDSS4 when the junction temperature is 300°C. The breakdown voltage BV2 is an example of a second breakdown voltage or an eighth breakdown voltage, the breakdown voltage BVDSS3 is an example of a third breakdown voltage or an ninth breakdown voltage, and the breakdown voltage BVDSS4 is an example of a fourth breakdown voltage or a tenth breakdown voltage.

[0088] Diode junction temperature T j The breakdown voltage at this point can be measured in the same manner as in the above-mentioned method for measuring the breakdown voltage of a transistor.

[0089] The breakdown voltage BV2 of the first transistor 110 within the junction temperature range of 50°C to 70°C is lower than the breakdown voltage BV1 of the first diode 120 within the junction temperature range of 50°C to 70°C. That is, the breakdown voltage BV2 when the junction temperature of the first transistor 110 is 70°C is lower than the breakdown voltage BV1 when the junction temperature of the first diode 120 is 50°C. Therefore, when the junction temperature of the first transistor 110 is within the temperature range of 50°C to 70°C, the first transistor 110 breaks down before the first diode 120 when the upper arm 100 transitions to a dynamic avalanche state. Note that, during operation of the semiconductor device 1, the junction temperatures of the first transistor 110 and the first diode 120 do not need to be the same.

[0090] The breakdown voltage BV2 of the second transistor 210 within the junction temperature range of 50°C to 70°C is lower than the breakdown voltage BV1 of the second diode 220 within the junction temperature range of 50°C to 70°C. That is, the breakdown voltage BV2 when the junction temperature of the second transistor 210 is 70°C is lower than the breakdown voltage BV1 when the junction temperature of the second diode 220 is 50°C. Therefore, when the junction temperatures of the second transistor 210 and the second diode 220 are within the temperature range of 50°C to 70°C, the second transistor 210 breaks down before the second diode 220 when the lower arm 200 transitions to a dynamic avalanche state. Note that the junction temperatures of the second transistor 210 and the second diode 220 do not need to be the same during operation of the semiconductor device 1.

[0091] In this embodiment, the breakdown voltage BV1 of the first diode 120 within the junction temperature range of 50°C or more and 70°C or less is between the breakdown voltage BVDSS3 when the junction temperature of the first transistor 110 is 50°C and the breakdown voltage BVDSS4 when the junction temperature is 300°C.

[0092] Furthermore, the breakdown voltage BV1 of the second diode 220 within the junction temperature range of 50°C or more and 70°C or less is between the breakdown voltage BVDSS3 when the junction temperature of the second transistor 210 is 50°C and the breakdown voltage BVDSS4 when the junction temperature is 300°C.

[0093] Focusing on the first transistor 110, the junction temperature of the first transistor 110 is, for example, 50°C or higher and 70°C or lower during the switching operations shown in FIGS. 9 to 12. Therefore, the first transistor 110 is not destroyed due to an increase in junction temperature. For example, during switching operations, a voltage lower than the rated voltage is applied between the P terminal 3 and the first O terminal 5 or the second O terminal 6. However, due to various factors, an overvoltage exceeding the rated voltage may be applied between the P terminal 3 and the O terminal, causing the upper arm 100 to transition to a dynamic avalanche state. For example, an overvoltage may be applied due to a surge voltage generated when a protection circuit is turned off due to a short circuit caused by a load failure, or may be applied when the switching speed becomes excessively fast due to a defect in the gate resistor, resulting in an excessive surge voltage.

[0094] Note that a junction temperature of, for example, 50°C or higher and 70°C or lower during operation of the first transistor 110, etc., is considered low. For example, the junction temperature is 50°C or higher and 70°C or lower immediately after the start of switching operation, under low load, in a low temperature environment, etc. Depending on the usage environment of the semiconductor device 1, the junction temperature may be higher or lower than the range of 50°C or higher and 70°C or lower.

[0095] Focusing on the second transistor 210, the junction temperature of the second transistor 210 is, for example, 50° C. or higher and 70° C. or lower while the switching operations shown in FIGS. 9 to 12 are being performed. Therefore, the second transistor 210 is not destroyed due to an increase in junction temperature. For example, in a normal switching operation, a voltage lower than the rated voltage is applied between the N terminal 4 and the first O terminal 5 or the second O terminal 6. However, due to various factors, an overvoltage exceeding the rated voltage may be applied between the N terminal 4 and the O terminal, causing the lower arm 200 to transition to a dynamic avalanche state.

[0096] Because the breakdown voltage BV2 of the first transistor 110 is lower than the breakdown voltage BV1 of the first diode 120, when the upper arm 100 transitions to a dynamic avalanche state, the first transistor 110 breaks down before the first diode 120. Then, an avalanche current flows through the first transistor 110, and the heat generated by the avalanche energy increases the junction temperature of the first transistor 110. When the junction temperature of the first transistor 110 reaches its breakdown temperature, the first transistor 110 is destroyed.

[0097] Similarly, because the breakdown voltage BV2 of the second transistor 210 is lower than the breakdown voltage BV1 of the second diode 220, when the lower arm 200 transitions to a dynamic avalanche state, the second transistor 210 breaks down before the second diode 220. Then, an avalanche current flows through the second transistor 210, and heat generated by the avalanche energy increases the junction temperature of the second transistor 210. When the junction temperature of the second diode 220 reaches its breakdown temperature, the second transistor 210 is destroyed.

[0098] In contrast, according to this embodiment, as described below, it is possible to prevent the junction temperature of the first transistor 110 and the junction temperature of the second transistor 210 from reaching the breakdown temperature, thereby improving the avalanche resistance.

[0099] In this embodiment, the first diode 120 and the first transistor 110 are arranged on different conductors. Therefore, when avalanche breakdown occurs in the first transistor 110, the temperature rises earlier, the avalanche breakdown voltage rises earlier, and breakdown of the first diode 120 begins, compared to when the first diode 120 and the first transistor 110 are arranged on a common conductor. Therefore, the avalanche current can be borne by the first diode 120 and the first transistor 110 earlier, and damage to the first transistor 110 that would otherwise be caused by the first transistor 110 solely carrying the current can be suppressed.

[0100] Similarly, in this embodiment, the second diode 220 and the second transistor 210 are arranged on different conductors. Therefore, when avalanche breakdown occurs in the second transistor 210, the temperature rises earlier, the avalanche breakdown voltage rises earlier, and breakdown of the second diode 220 begins, compared to when the second diode 220 and the second transistor 210 are arranged on a common conductor. Therefore, the avalanche current can be borne by the second diode 220 and the second transistor 210 earlier, and damage to the second transistor 210 that would otherwise be caused by the second transistor 210 carrying the current intensively can be suppressed.

[0101] Here, as an example, a description will be given of changes in voltage and current in the lower arm 200 when the semiconductor device 1 transitions to a dynamic avalanche state when switching from an ON state (see FIG. 12) in which a current I4 flows to an OFF state during a switching operation. FIG. 14 is a timing chart showing changes in voltage and current in the lower arm 200 when transitioning to a dynamic avalanche state.

[0102] During the period when the semiconductor device 1 is performing a switching operation, the junction temperature T jTr and the junction temperature T jDi The junction temperature T of the second transistor 210 is, for example, 50° C. or more and 70° C. or less in both the on state and the off state. jTr and the junction temperature T of the second diode 220 jDi may be the same as or different from each other.

[0103] In the ON state (see Figure 12) where current I4 flows, the voltage V between the N terminal 4 and the O terminal ON is substantially 0 V, and the second transistor 210 is supplied with a current I Tr flows, and the current I flows through the second diode 220 Di is effectively 0A.

[0104] If an overvoltage is applied between the N terminal 4 and the O terminal when switching from an ON state (see FIG. 12) in which a current I4 flows to an OFF state, the lower arm 200 transitions to a dynamic avalanche state. In this embodiment, the breakdown voltage BV2 of the second transistor 210 within the junction temperature range of 50° C. or more and 70° C. or less is lower than the breakdown voltage BV1 of the second diode 220 within the junction temperature range of 50° C. or more and 70° C. or less. Therefore, the second transistor 210 breaks down before the second diode 220 breaks down. In addition, as the second transistor 210 breaks down, the inter-terminal voltage V ON is 0V, the junction temperature T jTr The voltage rises sharply to the breakdown voltage BV2 corresponding to

[0105] Due to breakdown, the current I flows through the second transistor 210. Tr does not immediately drop to 0 A, but gradually drops. In other words, an avalanche current flows through the second transistor 210. Therefore, the second transistor 210 ON and current I Tr The power consumed is calculated by multiplying the power by the time, and heat energy is generated over time, which is calculated by multiplying the power by the time. jTr rises.

[0106] 13, the breakdown voltage BV2 of the second transistor 210 has temperature dependency, and increases as the junction temperature increases. jTr When the voltage V V increases, the breakdown voltage BV2 of the second transistor 210 increases, and the voltage V V V ON rises.

[0107] 13, in this embodiment, the breakdown voltage BV1 of the second diode 220 in the junction temperature range of 50° C. to 70° C. is between the breakdown voltage BVDSS3 when the junction temperature is 50° C. and the breakdown voltage BVDSS4 when the junction temperature is 300° C. Therefore, the junction temperature T jTrBefore reaching 300°C, the terminal voltage V ON However, the breakdown voltage BV1 of the second diode 220 is reached within the junction temperature range of 50° C. to 70° C., and the second diode 220 also breaks down.

[0108] Then, when the second diode 220 breaks down, an avalanche current also starts to flow through the second diode 220, and the avalanche current flowing through the second transistor 210 decreases accordingly. Therefore, the temperature rise of the second transistor 210 is suppressed, and the junction temperature T jTr 13, the junction temperature T jTr rises slightly, but the junction temperature T jTr may be decreased.

[0109] Therefore, according to this embodiment, even when the lower arm 200 transitions to a dynamic avalanche state, the breakdown of the second transistor 210 is suppressed, and the avalanche resistance can be improved.

[0110] Although not shown, when the upper arm 100 transitions to a dynamic avalanche state, the first transistor 110 breaks down before the first diode 120 breaks down, and an avalanche current flows through the first transistor 110, just as when the lower arm 200 transitions to a dynamic avalanche state (see FIG. 14). jTr rises, and the junction temperature T jTr As the voltage V V rises, the breakdown voltage BV2 of the first transistor 110 rises, and the voltage V V between the P terminal 3 and the O terminal PO rises.

[0111] 13, in this embodiment, the breakdown voltage BV1 of the first diode 120 in the junction temperature range of 50° C. to 70° C. is between the breakdown voltage BVDSS3 when the junction temperature is 50° C. and the breakdown voltage BVDSS4 when the junction temperature is 300° C. Therefore, the junction temperature T jTr Before reaching 300°C, the terminal voltage V PO However, the breakdown voltage BV1 of the first diode 120 is reached within the junction temperature range of 50° C. or more and 70° C. or less, and the first diode 120 also breaks down.

[0112] Then, when the first diode 120 breaks down, an avalanche current also starts to flow through the first diode 120, and the avalanche current flowing through the first transistor 110 decreases accordingly. Therefore, the temperature rise of the first transistor 110 is suppressed, and the junction temperature T jTr The temperature is prevented from reaching its destruction temperature.

[0113] Therefore, according to this embodiment, even when the upper arm 100 transitions to a dynamic avalanche state, the breakdown of the first diode 120 is suppressed, and the avalanche resistance can be improved.

[0114] Furthermore, multiple pairs of the first transistor 110 and the first diode 120 are connected in parallel between the P terminal 3 and the first O terminal 5 and the second O terminal 6, and multiple pairs of the second transistor 210 and the second diode 220 are connected in parallel between the N terminal 4 and the first O terminal 5 and the second O terminal 6. This allows a larger current to flow.

[0115] As described above, the breakdown voltages BV1 and BV2 have junction temperature dependence. Furthermore, as described above, when measuring the junction temperature dependence, the temperature of the environment in which the transistor or diode is placed (environmental temperature (also referred to as ambient temperature)), such as the temperature of a thermostatic chamber, can be considered to be the junction temperature of the transistor or diode. Therefore, the junction temperature dependence is equivalent to the environmental temperature dependence. In the above embodiment, as shown in FIG. 15 , the second breakdown voltage BV2 within the environmental temperature range of 50°C to 70°C is lower than the first breakdown voltage BV1 within the environmental temperature range of 50°C to 70°C, and the second breakdown voltage BV2 can be considered to include the third breakdown voltage BVDSS3 when the environmental temperature is 50°C and the fourth breakdown voltage BVDSS4 when the environmental temperature is 300°C. FIG. 15 is a diagram showing another example of the characteristics of the first transistor 110, the second transistor 210, the first diode 120, and the second diode 220. The horizontal axis in FIG. 15 represents the environmental temperature T e 15, the vertical axis represents the breakdown voltage. The solid line in FIG. 15 represents the characteristics of the first diode 120 and the second diode 220, and the two-dot chain line represents the characteristics of the first transistor 110 and the second transistor 210.

[0116] The breakdown voltage BV2 may have a breakdown voltage BVDSS5 when the junction temperature or environmental temperature is 250°C, and the breakdown voltage BV1 within the junction temperature or environmental temperature range of 50°C to 70°C may be between the breakdown voltages BVDSS3 and BVDSS5. In this case, even if the breakdown temperatures of the first transistor 110 and the second transistor 210 are 300°C or lower, as long as the breakdown temperatures exceed 250°C, an avalanche current can flow through the first diode 120 and the second diode 220 before the first transistor 110 and the second transistor 210 are destroyed, thereby improving the avalanche resistance of the upper arm 100 and the lower arm 200. The breakdown voltage BVDSS5 is an example of a fifth breakdown voltage or an eleventh breakdown voltage.

[0117] Alternatively, the breakdown voltage BV2 may have a breakdown voltage BVDSS6 when the junction temperature or the ambient temperature is 175°C, and the breakdown voltage BV1 within the junction temperature or the ambient temperature range of 50°C to 70°C may be between the breakdown voltages BVDSS3 and BVDSS6. In this case, even if the breakdown temperatures of the first transistor 110 and the second transistor 210 are 250°C or lower, as long as the breakdown temperatures exceed 175°C, an avalanche current can flow through the first diode 120 and the second diode 220 before the first transistor 110 and the second transistor 210 are destroyed, thereby improving the avalanche resistance of the upper arm 100 and the lower arm 200. The breakdown voltage BVDSS6 is an example of a sixth breakdown voltage or a twelfth breakdown voltage.

[0118] Generally, in a transistor, when the on-resistance is reduced, the breakdown voltage also tends to decrease, and it is not easy to obtain a high breakdown voltage while obtaining a low on-resistance. In this embodiment, even if the breakdown voltage of the first transistor 110 and the second transistor 210 is not particularly high, a good avalanche resistance can be obtained, and therefore a structure that obtains a low on-resistance can be adopted for the first transistor 110 and the second transistor 210.

[0119] The breakdown voltages of the first transistor 110, the first diode 120, the second transistor 210, and the second diode 220 can be adjusted by, for example, the impurity concentration of the semiconductor layers that make up these, the termination structure, and the like.

[0120] The first transistor 110 and the second transistor 210 may be field effect transistors such as MOS (metal-oxide-semiconductor) field effect transistors made of silicon carbide. The first diode 120 and the second diode 220 may be Schottky barrier diodes made of silicon carbide. The use of silicon carbide provides excellent breakdown voltage.

[0121] Although the embodiments have been described in detail above, the present invention is not limited to the specific embodiments, and various modifications and changes are possible within the scope of the claims. [Explanation of symbols]

[0122] 1: Semiconductor device 2: Heat sink 2A: 1st main surface 2B: 2nd main surface 3:P terminal (1st terminal, 3rd terminal) 4:N terminal (1st terminal, 3rd terminal) 5: 1st O terminal (2nd terminal) 6: 2nd O terminal (2nd terminal) 7, 8: Bonding material 9: Case 10: First insulating substrate 11, 12, 13, 14, 18, 19: Conductive layers 20: Second insulating substrate 21, 22, 23, 24, 25, 26, 27, 28, 29: Conductive layers 31, 32, 41, 42, 51, 52, 53, 54, 55, 61, 62, 63, 64, 65, 71, 72, 73, 74, 75, 81, 82, 83, 85, 86, 87: Wires 91, 92: Side wall 93, 94: End wall 95, 96: Terminal block 100: Upper arm 110: First transistor (first switching element, second switching element) 110A: First transistor group 111: First gate electrode 112: First source electrode 113: First drain electrode 120: First diode (first diode element, second diode element) 120A: First diode group 121: First anode electrode 122: First cathode electrode 131: First gate terminal 132: 1st sense source terminal 133: Sense drain terminal 200: Lower arm 210: Second transistor (first switching element, second switching element) 210A: Second transistor group 211: Second gate electrode 212: second source electrode 213: Second drain electrode 220: Second diode (first diode element, second diode element) 220A: Second diode group 221: Second anode electrode 222: second cathode electrode 231: Second gate terminal 232: Second sense source terminal 330: Thermistor 331: First thermistor terminal 332: Second thermistor terminal BV1: Breakdown voltage (1st breakdown voltage, 7th breakdown voltage) BV2: Breakdown voltage (2nd breakdown voltage, 8th breakdown voltage) BVDSS3: Breakdown voltage (3rd breakdown voltage, 9th breakdown voltage) BVDSS4: Breakdown voltage (4th breakdown voltage, 10th breakdown voltage) BVDSS5: Breakdown voltage (5th breakdown voltage, 11th breakdown voltage) BVDSS6: Breakdown voltage (6th breakdown voltage, 12th breakdown voltage) I1, I2, I3, I4, I Di , I Tr :Current T jDi , T jTr : Junction temperature V ON , V PO : Terminal voltage

Claims

1. A first terminal; A second terminal; a first diode element connected between the first terminal and the second terminal and having a first breakdown voltage that has junction temperature dependency; a first switching element connected in parallel to the first diode element between the first terminal and the second terminal, the first switching element having a second breakdown voltage having junction temperature dependency; and the second breakdown voltage within a junction temperature range of 50° C. to 70° C. is lower than the first breakdown voltage within a junction temperature range of 50° C. to 70° C., the second breakdown voltage includes a third breakdown voltage when the junction temperature is 50° C. and a fourth breakdown voltage when the junction temperature is 300° C.; The semiconductor device wherein the first breakdown voltage within a junction temperature range of 50° C. to 70° C. is between the third breakdown voltage and the fourth breakdown voltage.

2. the second breakdown voltage comprises a fifth breakdown voltage at a junction temperature of 250°C; 2. The semiconductor device according to claim 1, wherein the first breakdown voltage within a junction temperature range of 50[deg.] C. to 70[deg.] C. is between the third breakdown voltage and the fifth breakdown voltage.

3. the second breakdown voltage comprises a sixth breakdown voltage at a junction temperature of 175°C; 2. The semiconductor device according to claim 1, wherein the first breakdown voltage within a junction temperature range of 50[deg.] C. to 70[deg.] C. is between the third breakdown voltage and the sixth breakdown voltage.

4. A first terminal; A second terminal; a first diode element connected between the first terminal and the second terminal and having a first breakdown voltage that is dependent on ambient temperature; a first switching element connected in parallel to the first diode element between the first terminal and the second terminal, the first switching element having a second breakdown voltage that is dependent on ambient temperature; and the second breakdown voltage within an environmental temperature range of 50° C. to 70° C. is lower than the first breakdown voltage within an environmental temperature range of 50° C. to 70° C.; The second breakdown voltage includes a third breakdown voltage when the ambient temperature is 50° C. and a fourth breakdown voltage when the ambient temperature is 300° C.; The semiconductor device wherein the first breakdown voltage in an environmental temperature range of 50° C. to 70° C. is between the third breakdown voltage and the fourth breakdown voltage.

5. the second breakdown voltage comprises a fifth breakdown voltage at an ambient temperature of 250°C; 5. The semiconductor device according to claim 4, wherein the first breakdown voltage within an environmental temperature range of 50[deg.] C. to 70[deg.] C. is between the third breakdown voltage and the fifth breakdown voltage.

6. the second breakdown voltage comprises a sixth breakdown voltage at an ambient temperature of 175°C; 5. The semiconductor device according to claim 4, wherein the first breakdown voltage in an environmental temperature range of 50[deg.] C. to 70[deg.] C. is between the third breakdown voltage and the sixth breakdown voltage.

7. A first terminal; A second terminal; a first diode element connected between the first terminal and the second terminal and having a first breakdown voltage that has junction temperature dependency; a first switching element connected in parallel to the first diode element between the first terminal and the second terminal, the first switching element having a second breakdown voltage having junction temperature dependency; and the second breakdown voltage within a junction temperature range of 50° C. to 70° C. is lower than the first breakdown voltage within a junction temperature range of 50° C. to 70° C., When the transition to the dynamic avalanche state occurs, An avalanche current flows through the first switching element, The avalanche current flows, causing the junction temperature of the first switching element to rise, When the junction temperature of the first switching element increases, the inter-terminal voltage between the first terminal and the second terminal increases, When the inter-terminal voltage rises and reaches the first breakdown voltage of the first diode element, an avalanche current flows through the first diode element before the first switching element is broken down.

8. A first terminal; A second terminal; a first diode element connected between the first terminal and the second terminal and having a first breakdown voltage that is dependent on ambient temperature; a first switching element connected in parallel to the first diode element between the first terminal and the second terminal, the first switching element having a second breakdown voltage that is dependent on ambient temperature; and the second breakdown voltage within an environmental temperature range of 50° C. to 70° C. is lower than the first breakdown voltage within an environmental temperature range of 50° C. to 70° C.; When the transition to the dynamic avalanche state occurs, An avalanche current flows through the first switching element, The avalanche current flows, causing the junction temperature of the first switching element to rise, When the junction temperature of the first switching element increases, the inter-terminal voltage between the first terminal and the second terminal increases, When the inter-terminal voltage rises and reaches the first breakdown voltage of the first diode element, an avalanche current flows through the first diode element before the first switching element is broken down.

9. When the transition to the dynamic avalanche state occurs, An avalanche current flows through the first switching element, The avalanche current flows, causing the junction temperature of the first switching element to rise, When the junction temperature of the first switching element increases, the inter-terminal voltage between the first terminal and the second terminal increases, 7. The semiconductor device according to claim 1, wherein the inter-terminal voltage increases and reaches the first breakdown voltage of the first diode element, causing an avalanche current to flow through the first diode element before the first switching element is broken down.

10. 10. The semiconductor device according to claim 1, wherein a plurality of pairs of the first switching element and the first diode element are connected in parallel between the first terminal and the second terminal.

11. the first switching element is a field effect transistor made of silicon carbide, 11. The semiconductor device according to claim 1, wherein the first diode element is a Schottky barrier diode made of silicon carbide.

12. A third terminal; a second diode element connected between the third terminal and the second terminal, the second diode element having a seventh breakdown voltage having junction temperature dependency; a second switching element connected in parallel to the second diode element between the third terminal and the second terminal, the second switching element having an eighth breakdown voltage having junction temperature dependency; and the eighth breakdown voltage within a junction temperature range of 50° C. to 70° C. is lower than the seventh breakdown voltage within a junction temperature range of 50° C. to 70° C.; The eighth breakdown voltage includes a ninth breakdown voltage when the junction temperature is 50° C. and a tenth breakdown voltage when the junction temperature is 300° C.; 12. The semiconductor device according to claim 1, wherein the seventh breakdown voltage within a junction temperature range of 50° C. to 70° C. is between the ninth breakdown voltage and the tenth breakdown voltage.

13. the eighth breakdown voltage comprises an eleventh breakdown voltage when the junction temperature is 250°C; 13. The semiconductor device according to claim 12, wherein the seventh breakdown voltage within a junction temperature range of 50° C. to 70° C. is between the ninth breakdown voltage and the eleventh breakdown voltage.

14. the eighth breakdown voltage comprises a twelfth breakdown voltage at a junction temperature of 175°C; 13. The semiconductor device according to claim 12, wherein the seventh breakdown voltage within a junction temperature range of 50° C. to 70° C. is between the ninth breakdown voltage and the twelfth breakdown voltage.

15. A third terminal; a second diode element connected between the third terminal and the second terminal and having a seventh breakdown voltage that is dependent on ambient temperature; a second switching element connected in parallel to the second diode element between the third terminal and the second terminal, the second switching element having an eighth breakdown voltage that is dependent on ambient temperature; and the eighth breakdown voltage in an environmental temperature range of 50° C. to 70° C. is lower than the seventh breakdown voltage in an environmental temperature range of 50° C. to 70° C.; The eighth breakdown voltage includes a ninth breakdown voltage when the ambient temperature is 50° C. and a tenth breakdown voltage when the ambient temperature is 300° C.; 12. The semiconductor device according to claim 1, wherein the seventh breakdown voltage within an environmental temperature range of 50° C. to 70° C. is between the ninth breakdown voltage and the tenth breakdown voltage.

16. The eighth breakdown voltage comprises an eleventh breakdown voltage when the ambient temperature is 250°C; 16. The semiconductor device according to claim 15, wherein the seventh breakdown voltage within an environmental temperature range of 50° C. to 70° C. is between the ninth breakdown voltage and the eleventh breakdown voltage.

17. the eighth breakdown voltage comprises a twelfth breakdown voltage when the ambient temperature is 175°C; 16. The semiconductor device according to claim 15, wherein the seventh breakdown voltage within an environmental temperature range of 50° C. to 70° C. is between the ninth breakdown voltage and the twelfth breakdown voltage.

18. A third terminal; a second diode element connected between the third terminal and the second terminal, the second diode element having a seventh breakdown voltage having junction temperature dependency; a second switching element connected in parallel to the second diode element between the third terminal and the second terminal, the second switching element having an eighth breakdown voltage having junction temperature dependency; and the eighth breakdown voltage within a junction temperature range of 50° C. to 70° C. is lower than the seventh breakdown voltage within a junction temperature range of 50° C. to 70° C.; When the transition to the dynamic avalanche state occurs, An avalanche current flows through the second switching element, The avalanche current flows, causing the junction temperature of the second switching element to rise, When the junction temperature of the second switching element increases, the inter-terminal voltage between the third terminal and the second terminal increases, 12. The semiconductor device according to claim 1, wherein the inter-terminal voltage increases and reaches the seventh breakdown voltage of the second diode element, causing an avalanche current to flow through the second diode element before the second switching element is broken down.

19. A third terminal; a second diode element connected between the third terminal and the second terminal and having a seventh breakdown voltage that is dependent on ambient temperature; a second switching element connected in parallel to the second diode element between the third terminal and the second terminal, the second switching element having an eighth breakdown voltage that is dependent on ambient temperature; and the eighth breakdown voltage in an environmental temperature range of 50° C. to 70° C. is lower than the seventh breakdown voltage in an environmental temperature range of 50° C. to 70° C.; When the transition to the dynamic avalanche state occurs, An avalanche current flows through the second switching element, The avalanche current flows, causing the junction temperature of the second switching element to rise, When the junction temperature of the second switching element increases, the inter-terminal voltage between the third terminal and the second terminal increases, 12. The semiconductor device according to claim 1, wherein the inter-terminal voltage increases and reaches the seventh breakdown voltage of the second diode element, causing an avalanche current to flow through the second diode element before the second switching element is broken down.

20. When the transition to the dynamic avalanche state occurs, An avalanche current flows through the second switching element, The avalanche current flows, causing the junction temperature of the second switching element to rise, When the junction temperature of the second switching element increases, the inter-terminal voltage between the third terminal and the second terminal increases, 18. The semiconductor device according to claim 12, wherein the inter-terminal voltage increases and reaches the seventh breakdown voltage of the second diode element, causing an avalanche current to flow through the second diode element before the second switching element is broken down.

21. 21. The semiconductor device according to claim 12, wherein a plurality of pairs of the second switching element and the second diode element are connected in parallel between the third terminal and the second terminal.

22. the second switching element is a field effect transistor made of silicon carbide, 22. The semiconductor device according to claim 12, wherein the second diode element is a Schottky barrier diode made of silicon carbide.

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