Voltage generation circuit, gate driver, and semiconductor module

Abstract

To provide a voltage generation circuit, gate driver, and semiconductor module that can generate a constant voltage with a simple configuration. [Solution] The voltage generation circuit comprises a first terminal, a second terminal, a depletion-type field-effect transistor, a first diode connected between the first terminal and the field-effect transistor, and a first capacitor connected between the field-effect transistor and ground. The anode terminal of the first diode is connected to the first terminal, the cathode terminal of the first diode is connected to the drain terminal of the field-effect transistor, the source terminal of the field-effect transistor is connected to the second terminal and one end of the first capacitor, and the gate terminal of the field-effect transistor is connected to the other end of the first capacitor.

Description

[Technical Field]

[0001] Embodiments of the present invention relate to a voltage generation circuit, a gate driver, and a semiconductor module. [Background technology]

[0002] For example, semiconductor switching elements such as power devices are switched on and off by a gate control signal from a gate drive circuit. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Patent No. 6400545 [Overview of the project] [Problems that the invention aims to solve]

[0004] Embodiments of the present invention aim to provide a voltage generation circuit, a gate driver, and a semiconductor module that can generate a constant voltage with a simple configuration. [Means for solving the problem]

[0005] According to an embodiment of the present invention, the voltage generation circuit comprises a first terminal, a second terminal, a depletion-type field-effect transistor, a first diode connected between the first terminal and the field-effect transistor, and a first capacitor connected between the field-effect transistor and ground, wherein the anode terminal of the first diode is connected to the first terminal, the cathode terminal of the first diode is connected to the drain terminal of the field-effect transistor, the source terminal of the field-effect transistor is connected to the second terminal and one end of the first capacitor, and the gate terminal of the field-effect transistor is connected to the other end of the first capacitor. [Brief explanation of the drawing]

[0006] [Figure 1] It is a circuit diagram of a semiconductor module of an embodiment. [Figure 2A] It is a circuit diagram of a voltage generation circuit of the first embodiment. [Figure 2B] It is a circuit diagram of a voltage generation circuit of the first embodiment. [Figure 3] (a) is a waveform diagram of the input voltage Vin of the voltage generation circuit, and (b) is a waveform diagram of the output voltage Vout of the voltage generation circuit. [Figure 4] It is a circuit diagram of a voltage generation circuit of the second embodiment. [Figure 5A] It is a circuit diagram of a voltage generation circuit of the third embodiment. [Figure 5B] It is a circuit diagram of a voltage generation circuit of the third embodiment. [Figure 6] (a) is a waveform diagram of the source potential VC1 of the field effect transistor M1 in the voltage generation circuit of the third embodiment, and (b) is a waveform diagram of the gate potential Vg of the field effect transistor M1 that changes corresponding to the change in the potential VC1 in FIG. 6(a). [Figure 7A] It is a circuit diagram of a voltage generation circuit of the fourth embodiment. [Figure 7B] It is a circuit diagram of a voltage generation circuit of the fourth embodiment. [Figure 7C] It is a circuit diagram of a voltage generation circuit of the fourth embodiment. [Figure 8] It is a schematic cross-sectional view of an example of a field effect transistor in the voltage generation circuit of the embodiment. [Figure 9] It is a schematic cross-sectional view of a semiconductor device of the embodiment. [Figure 10] It is a schematic perspective view of a semiconductor device of the embodiment. [Figure 11] It is a schematic perspective view of a semiconductor device of the embodiment. [Figure 12] It is a schematic cross-sectional view of a semiconductor device of the embodiment. [Figure 13] (a) and (b) are schematic perspective views of a semiconductor device of the embodiment. [Figure 14] It is a schematic perspective view of a semiconductor device of the embodiment. [Figure 15]This is a schematic cross-sectional view of the semiconductor device according to the embodiment. [Modes for carrying out the invention]

[0007] Each embodiment will be described below with reference to the drawings. The drawings are schematic or conceptual, and the relationships between the thickness and width of each part, as well as the ratios of the sizes of the parts, are not necessarily identical to those of reality. Even when representing the same part, the dimensions and ratios may be shown differently in different drawings. Also, the same or similar elements are given the same symbols. Furthermore, in the explanation of circuit diagrams, "connection" means "electrically connected."

[0008] Figure 1 is a circuit diagram of a semiconductor module 100 according to an embodiment. The semiconductor module 100 includes a gate driver 200 and a semiconductor switching element 300. The gate driver 200 and the semiconductor switching element 300 are separate package components. Alternatively, the gate driver 200 and the semiconductor switching element 300 are integrated into a single package.

[0009] The semiconductor switching element 300 is a power device for power control, and is, for example, a field-effect transistor (MOSFET: Metal-Oxide-Semiconductor Field Effect Transistor). Alternatively, the semiconductor switching element 300 may be an insulated-gate bipolar transistor (IGBT: Insulated Gate Bipolar Transistor).

[0010] The semiconductor switching element 300 is, for example, an n-type MOSFET, and the drain terminal D of the semiconductor switching element 300 is connected to the power line 400. The semiconductor switching element 300 is, for example, a high-side element in a power conversion circuit in which a high-side element and a low-side element are connected in series between the power line 400 and ground. The source terminal S of the semiconductor switching element 300 is connected to the drain terminal of the low-side element. The source terminal of the low-side element is connected to ground. The source terminal S of the semiconductor switching element 300 is connected to ground via the low-side element. If the semiconductor switching element 300 is an IGBT, the drain terminal can be replaced with the collector terminal and the source terminal can be replaced with the emitter terminal.

[0011] Furthermore, the gate driver 200 of this embodiment can also be used as a gate driver for a low-side element.

[0012] The gate driver 200 includes a gate drive circuit 210, a voltage generation circuit 10, and a photocoupler 220. The gate drive circuit 210 includes a first semiconductor element 211, a second semiconductor element 212, and a control circuit 215.

[0013] The first semiconductor element 211 and the second semiconductor element 212 are, for example, n-type MOSFETs. The drain terminal of the first semiconductor element 211 is connected to the voltage input line 201 of the gate drive circuit 210. The voltage input line 201 of the gate drive circuit 210 is connected to the voltage generation circuit 10. The source terminal of the first semiconductor element 211 is connected to the drain terminal of the second semiconductor element 212. The source terminal of the first semiconductor element 211 and the drain terminal of the second semiconductor element 212 are connected to the output terminal 205 of the gate drive circuit 210. The output terminal 205 of the gate drive circuit 210 is connected to the gate terminal G of the semiconductor switching element 300. The source terminal of the second semiconductor element 212 is connected to the reference potential line 202 of the gate drive circuit 210. The reference potential line 202 of the gate drive circuit 210 is connected to the source terminal S of the semiconductor switching element 300.

[0014] The control circuit 215 is connected between the voltage input line 201 and the reference potential line 202 of the gate drive circuit 210. The gate terminals of the first semiconductor element 211 and the second semiconductor element 212 are connected to the control circuit 215.

[0015] The photocoupler 220 includes a light-emitting element 221 and a light-receiving element 222. The light-emitting element 221 outputs a gate control signal, which is input as an electrical signal from an external circuit, as an optical signal. The light-receiving element 222 is connected between the voltage input line 201 and the reference potential line 202 of the gate drive circuit 210. The light-receiving element 222 receives the optical signal emitted by the light-emitting element 221, converts it into an electrical signal, and outputs it to the control circuit 215. Based on the gate control signal input from the light-receiving element 222, the control circuit 215 controls the potential of the gate terminal of the first semiconductor element 211 and the gate terminal of the second semiconductor element 212. The control circuit 215 alternately turns the first semiconductor element 211 and the second semiconductor element 212 on and off.

[0016] The voltage generation circuit 10 supplies a DC voltage to the voltage input line 201 of the gate drive circuit 210. As the first semiconductor element 211 and the second semiconductor element 212 are alternately turned on and off, a pulse voltage is output to the output terminal 205 of the gate drive circuit 210. This pulse voltage is supplied to the gate terminal G of the semiconductor switching element 300, causing the semiconductor switching element 300 to be turned on and off.

[0017] The following describes specific examples of the voltage generation circuit 10. As the voltage generation circuit 10 shown in Figure 1, one of the voltage generation circuits 10A to 10D of the embodiments described below, or a combination of two or more of them, can be used.

[0018] Figure 2A is a circuit diagram of the voltage generation circuit 10A of the first embodiment. The voltage generation circuit 10A of the first embodiment has a first terminal 11, a second terminal 12, a field-effect transistor M1, a first diode D1, and a first capacitor C1. The voltage generation circuit 10A also has, for example, a ground terminal 13.

[0019] The first terminal 11 is a voltage input terminal and is connected to the drain terminal D of the semiconductor switching element 300 shown in Figure 1. The second terminal 12 is a voltage output terminal and is connected to the voltage input line 201 of the gate drive circuit 210 shown in Figure 1. The first diode D1, the field-effect transistor M1, and the first capacitor C1 are connected in series between the first terminal 11 and ground.

[0020] The field-effect transistor M1 is a depletion-type field-effect transistor with a negative threshold voltage (-Vth). For example, the field-effect transistor M1 is an n-type MOSFET.

[0021] The first diode D1 is connected between the first terminal 11 and the field-effect transistor M1. The anode terminal t1 of the first diode D1 is connected to the first terminal 11, and the cathode terminal t2 of the first diode D1 is connected to the drain terminal D of the field-effect transistor M1. M1 It is connected to this.

[0022] The first capacitor C1 is connected between the field-effect transistor M1 and the ground terminal 13. The source terminal S of the field-effect transistor M1. M1 It is connected to the second terminal 12 and one end t3 of the first capacitor C1. The gate terminal G of the field-effect transistor M1 M1 This is connected to the other end t4 of the first capacitor C1. The other end t4 of the first capacitor C1 is connected to the ground terminal 13.

[0023] The voltage generation circuit 10A of the first embodiment may further include a Zener diode DZ. The anode terminal t5 of the Zener diode DZ is connected to the other terminal t4 of the first capacitor C1. The cathode terminal t6 of the Zener diode DZ is connected to the source terminal S of the field-effect transistor M1. M1 It is also connected to terminal 2 12.

[0024] Furthermore, the voltage generation circuit 10A of the first embodiment has a source terminal S of the field-effect transistor M1. M1 The system may further include a second diode D2 for preventing reverse current, connected between the second terminal 12 and the second terminal 12. The anode terminal t9 of the second diode D2 is connected to the source terminal S. M1 The cathode terminal t10 of the second diode D2 is connected to the second terminal 12.

[0025] A voltage across the semiconductor switching element 300 (drain-source voltage) is applied between the first terminal 11 of the voltage generation circuit 10A and the other terminal t4 of the first capacitor C1. As the semiconductor switching element 300 repeatedly switches on and off, the drain-source voltage of the semiconductor switching element 300 changes in a pulsed manner.

[0026] As shown in Figure 2B, the voltage generation circuit 10A may have multiple field-effect transistors, including field-effect transistor M1, and multiple capacitors, including first capacitor C1. Multiple sets of field-effect transistors and capacitors are connected between the cathode terminal t2 of the first diode D and the anode terminal t5 of the Zener diode DZ. According to the voltage generation circuit 10A shown in Figure 2B, the generated voltage increases.

[0027] Figure 3(a) shows an example of the drain-source voltage of the semiconductor switching element 300, that is, the input voltage Vin applied between the first terminal 11 of the voltage generation circuit 10A and the other terminal t4 of the first capacitor C1. In this example, when the semiconductor switching element 300 is off, the input voltage Vin is 40V, and when the semiconductor switching element 300 is on, the input voltage Vin is 0V.

[0028] Figure 3(b) is a waveform diagram of the output voltage Vout output at the second terminal 12 when the input voltage Vin shown in Figure 3(a) is given. Figures 3(a) and 3(b) are the results obtained from simulations.

[0029] When the first capacitor C1 is not charged and the potential of the second terminal 12 (output voltage Vout) is 0V, the source terminal S of the field-effect transistor M1 M1 The potential (source potential) and the gate terminal G M1 The potentials (gate potentials) of both are 0V, and the depletion-type field-effect transistor M1 is in the ON state.

[0030] Current flows from the first terminal 11 through the first diode D1 and the ON field-effect transistor M1, charging the first capacitor C1. As the first capacitor C1 charges, the source potential of the field-effect transistor M1 rises from 0V, and the gate potential decreases relative to the source potential. The threshold voltage of the field-effect transistor M1 is set to -2V. When the source potential rises to 2V, the gate voltage of the field-effect transistor M1 (the difference between the gate potential and the source potential) reaches the threshold voltage (-2V), the field-effect transistor M1 turns off, and no current flows to the first capacitor C1. As a result, the voltage generation circuit 10A outputs a constant voltage (2V) to the second terminal 12, as shown in Figure 3(b).

[0031] The first diode D1 prevents current from flowing back into the first terminal 11 due to discharge from the first capacitor C1 when the potential of the first terminal 11 drops to 0V.

[0032] According to this embodiment, a constant voltage for the gate drive circuit 210, for example, can be generated from the voltage across both ends (drain-source voltage) of the semiconductor switching element 300 with a simple configuration. An external power supply for the gate drive circuit 210 is not required separately. Also, when the source potential becomes a predetermined potential, the field effect transistor M1 turns off, and even if a voltage is applied across the drain and source of the semiconductor switching element 300, no current flows to charge the first capacitor C1, so power consumption can be reduced.

[0033] Even when the field effect transistor M1 is off, there is a concern that the first capacitor C1 may be charged by a leakage current over a long period, causing the source potential to rise more than necessary. According to this embodiment, when the source potential rises more than necessary and the Zener diode DZ reaches its breakdown voltage, a current can be discharged from the source terminal S M1 to ground through the Zener diode DZ. Thereby, an increase in the output voltage Vout can be prevented.

[0034] FIG. 4 is a circuit diagram of the voltage generation circuit 10B of the second embodiment.

[0035] The voltage generation circuit 10B of the second embodiment further includes a second capacitor C2 connected in series with the first capacitor C1. The gate terminal G M1 of the field effect transistor M1 is connected between the first capacitor C1 and the second capacitor C2.

[0036] In the second embodiment as well, the threshold voltage Vth of the field-effect transistor M1 is set to, for example, -2V. Since the first capacitor C1 and the second capacitor C2 are connected in series, the charge stored in the first capacitor C1 and the charge stored in the second capacitor C2 are the same. For example, if the capacitance of the first capacitor C1 is 8nF and the capacitance of the second capacitor C2 is 2nF, the voltage across the second capacitor C2 will be four times the voltage across the first capacitor C1. For example, if the first capacitor C1 is charged to 2V and the field-effect transistor M1 is turned off, the second capacitor C2 will be charged to 8V. Therefore, the source potential of the field-effect transistor M1 can be raised to 10V, which is higher than -Vth=+2V, and a constant voltage of 10V can be output to the second terminal 12.

[0037] Figure 5A is a circuit diagram of the voltage generation circuit 10C of the third embodiment.

[0038] The voltage generation circuit 10C of the third embodiment is connected to the gate terminal G of the field-effect transistor M1. M1 and source terminal S M1 The circuit further includes a buffer circuit 20 connected between the NOT gate and the NOT gate. The buffer circuit 20 can be, for example, an inverter, a comparator, a trigger circuit, a Schmitt trigger circuit, etc. The comparator, trigger circuit, and Schmitt trigger circuit can be combined with the NOT gate.

[0039] Figure 5B is a circuit diagram of a voltage generation circuit 10C in an example where inverter 20A is used as the buffer circuit 20.

[0040] The inverter 20A includes a third semiconductor element 23 and a fourth semiconductor element 24. For example, the third semiconductor element 23 is a p-type MOSFET, and the fourth semiconductor element 24 is an n-type MOSFET. The third semiconductor element 23 and the fourth semiconductor element 24 constitute a CMOS circuit.

[0041] Furthermore, the voltage generation circuit 10C has a third terminal 21, a third diode D3, and a fourth capacitor C4. Voltage for driving the inverter 20A is supplied from the third terminal 21 to the voltage supply line 22 of the inverter 20A.

[0042] The third diode D3 is connected between the third terminal 21 and the source terminal of the third semiconductor element 23. The anode terminal of the third diode D3 is connected to the third terminal 21, and the cathode terminal of the third diode D3 is connected to the source terminal of the third semiconductor element 23. One end t11 of the fourth capacitor C4 is connected to the voltage supply line 22 between the cathode terminal of the third diode D3 and the source terminal of the third semiconductor element 23. The other end t12 of the fourth capacitor C4 is connected to the reference potential line 27 of the inverter 20A.

[0043] The drain terminal of the third semiconductor element 23 is connected to the voltage supply line 22. The source terminal of the fourth semiconductor element 24 is connected to the reference potential line 27. The gate terminals of the third semiconductor element 23 and the fourth semiconductor element 24 are connected to the source terminal S of the field-effect transistor M1. M1 The drain terminal of the third semiconductor element 23 and the drain terminal of the fourth semiconductor element 24 are connected to the gate terminal G of the field-effect transistor M1. M1 It is connected to this.

[0044] Figure 6(a) shows the source potential V of the field-effect transistor M1. C1 This is the waveform diagram. Figure 6(b) is the waveform diagram of the gate potential Vg of the field-effect transistor M1. Figures 6(a) and 6(b) are the results obtained from simulations.

[0045] Source potential V C1 When the voltage is 0V, the third semiconductor element 23 turns on and the fourth semiconductor element 24 turns off. As a result, the gate terminal G of the field-effect transistor M1 is connected via the ON state of the third semiconductor element 23. M1 When the potential of the third terminal 21 is applied, the field-effect transistor M1 turns on.

[0046] As mentioned above, when the first capacitor C1 is charged, the source potential V is as shown in Figure 6(a). C1 The source potential V increases. C1 When the voltage exceeds the first threshold V1, the third semiconductor element 23 turns off and the fourth semiconductor element 24 turns on. As a result, the gate potential Vg becomes 0V. For example, source potential V C1 From this perspective, the gate potential Vg becomes -2V, and the field-effect transistor M1 turns off. As a result, charging of the first capacitor C1 stops, and a constant voltage (e.g., 2V) is output to the second terminal 12, as described above.

[0047] MOSFETs tend to have high resistance near the threshold voltage Vth, and current loss tends to be large when current flows through them. In this embodiment, the buffer circuit 20 controls the source potential V of the field-effect transistor M1. C1 However, if the voltage exceeds the first threshold voltage V1 before reaching a predetermined potential (e.g., 2V), the gate potential Vg of the field-effect transistor M1 is changed to a potential lower than the threshold voltage Vth of the field-effect transistor M1, thereby turning off the field-effect transistor M1. This shortens the period during which current flows near the threshold voltage Vth of the field-effect transistor M1, thereby reducing losses.

[0048] Figures 7A, 7B, and 7C are circuit diagrams of the voltage generation circuit 10D according to the fourth embodiment.

[0049] As shown in Figure 7A, the voltage generation circuit 10D of the fourth embodiment includes a third capacitor C3 and a series-parallel switching circuit 30. In Figures 7A and 7B, the series-parallel switching circuit 30 is exemplified as having three switching elements SW1 to SW3. For example, semiconductor elements can be used as the switching elements SW1 to SW3.

[0050] The series-parallel switching circuit 30 connects to the source terminal S of the field-effect transistor M1. M1It is connected to one end t3 of the first capacitor C1 and the other end t4 of the first capacitor C1. The series-parallel switching circuit 30 is also connected to the second terminal 12 and the third capacitor C3.

[0051] One end of the switching element SW3 is connected to the source terminal S of the field-effect transistor M1. M1 The other end of the switching element SW3 is connected to the second terminal 12 and one end t15 of the third capacitor C3.

[0052] One end of the switching element SW1 is connected to the other end t4 of the first capacitor C3. The other end of the switching element SW1 is connected to the other end t16 of the third capacitor C3.

[0053] One end of the switching element SW2 is connected to the source terminal S of the field-effect transistor M1. M1 , and is connected to one end of switching element SW3. The other end of switching element SW2 is connected to the other end of switching element SW1 and the other end t16 of the third capacitor C3.

[0054] The series-parallel switching circuit 30 can switch between a first state (shown in Figure 7C) in which the first capacitor C1 and the third capacitor C3 are connected in parallel with respect to the field-effect transistor M1, and a second state (shown in Figure 7B) in which the first capacitor C1 and the third capacitor C3 are connected in series with respect to the field-effect transistor M1.

[0055] As shown in Figure 7C, when switching element SW2 is ON and switching elements SW1 and SW3 are OFF, the first capacitor C1 and the third capacitor C3 are connected in parallel to the field-effect transistor M1. As a result, if the input voltage to the first terminal 11 (the voltage across the semiconductor switching element 300 shown in Figure 1) is, for example, 5V, then 5V is charged to both the first capacitor C1 and the third capacitor C3.

[0056] As shown in Figure 7B, when switching elements SW1 and SW3 are on and switching element SW2 is off, the first capacitor C1 and the third capacitor C3 are connected in series with respect to the field-effect transistor M1. As a result, 10V is output to the second terminal 12.

[0057] According to this embodiment, a voltage higher than the input voltage to the first terminal 11 can be output to the second terminal 12.

[0058] According to the voltage generation circuits 10A to 10D of the embodiments described above, a constant voltage is generated from the voltage across the semiconductor switching element 300 (drain-source voltage). Therefore, by monitoring the output voltage from the second terminal 12, it becomes possible to detect a failure in the semiconductor switching element 300.

[0059] Figure 8 is a schematic cross-sectional view of an example of a field-effect transistor M1 in the voltage generation circuits 10A to 10D of the embodiments described above. In Figure 8, the X1 axis, Y1 axis, and Z1 axis indicate direction. The direction along the X1 axis is called the first direction X1. The direction along the Y1 axis is called the second direction Y1, and the second direction Y1 is perpendicular to the first direction X1. The direction along the Z1 axis is called the third direction Z1, and the third direction Z1 is perpendicular to both the first direction X1 and the second direction Y1.

[0060] In this specification, the first conductivity type in the semiconductor layer is defined as n-type, and the second conductivity type as p-type. However, the first conductivity type may be p-type and the second conductivity type as n-type. The semiconductor layer is, for example, a silicon layer. Alternatively, the semiconductor layer may be a silicon carbide layer, a gallium nitride layer, or the like.

[0061] The field-effect transistor M1 comprises a first electrode 591, an n-type first semiconductor layer 510 provided on the first electrode 591, a second electrode 592 provided on the first semiconductor layer 510, and a first gate electrode 540. The first electrode 591 is connected to the drain terminal D described above. M1 It is electrically connected to the source terminal S mentioned above. The second electrode 592 is connected to the source terminal S. M1 It is electrically connected to the gate terminal G mentioned above. The first gate electrode 540 is connected to the gate terminal GM1 It is electrically connected to it.

[0062] In the ON state of the field-effect transistor M1, where the gate voltage of the first gate electrode 540 is higher than the threshold voltage, current flows vertically (third direction Z1) between the first electrode 591 and the second electrode 592 through the first semiconductor layer 510. In the third direction Z1, the direction from the first electrode 591 to the second electrode 592 is defined as upward or upward, and the direction from the second electrode 592 to the first electrode 591 is defined as downward or downward.

[0063] The first semiconductor layer 510 has a plurality of mesa portions 511 that are spaced apart from each other in a first direction X1 and extend in a second direction Y1. A trench structure T having a gate electrode 540 is provided adjacent to the mesa portions 511 in the first direction X1. A plurality of trench structures T are lined up in the first direction X1. Each trench structure T extends in the second direction Y1.

[0064] The second electrode 592 is located in a recess 511A provided on the upper part of the mesa portion 511. The recess 511A and the second electrode 592 within the recess 511A extend in the second direction Y1. The second electrode 592 is also provided on the trench structure T.

[0065] The trench structure T further includes an insulating layer 552 provided between the gate electrode 540 and the second electrode 592 in the third direction Z1, and a first insulating film 551 provided between the mesa portion 511 and the gate electrode 540 in the first direction X1.

[0066] The trench structure T may further include a field plate electrode 560 and a second insulating film 553. The field plate electrode 560 is located below the gate electrode 540. The second insulating film 553 is provided between the gate electrode 540 and the field plate electrode 560, and between the field plate electrode 560 and the first semiconductor layer 510.

[0067] The portion of the mesa 511 located between the trench structure T and the second electrode 592 (recess 511A) has a first side surface 511S1 and a second side surface 511S2. The first side surface 511S1 faces the gate electrode 540 via the first insulating film 551 in the first direction X1. The second side surface 511S2 is located on the opposite side of the first side surface 511S1 in the first direction X1. The second electrode 592 in the recess 511A is in contact with the second side surface 511S2.

[0068] The portion of the mesa portion 511 between the first side surface 511S1 and the second side surface 511S2 has a channel portion 511B and a contact portion 511C. The channel portion 511B faces the gate electrode 540 via the first insulating film 551 in the first direction X1. The contact portion 511C is provided on the channel portion 511B. The n-type impurity concentration of the contact portion 511C is higher than the n-type impurity concentration of the channel portion 511B. The mesa portion 511 does not contain a p-type semiconductor layer.

[0069] The second electrode 592 is made of a metallic material. The second electrode 592 and the second side surface 511S2 of the channel portion 511B form a Schottky junction. The second electrode 592 is in direct contact with the second side surface 511S2 of the channel portion 511B. Alternatively, the second electrode 592 may be in contact with the second side surface 511S2 of the channel portion 511B via an insulating film. The second electrode 592 is in ohmic contact with the second side surface 511S2 of the contact portion 511C.

[0070] The field-effect transistor M1 further comprises an n-type semiconductor layer 530 provided between the first electrode 591 and the first semiconductor layer 510 and electrically connected to the first electrode 591. The n-type impurity concentration of the semiconductor layer 530 is higher than that of the first semiconductor layer 510.

[0071] When the field-effect transistor M1 is in the ON state, current flows between the first electrode 591 and the second electrode 592 via the contact portion 511C and the channel portion 511B.

[0072] In the off state of the field-effect transistor M1, the channel portion 511B is depleted by a depletion layer extending in the first direction X1 from the Schottky junction between the second side surface 511S2 of the channel portion 511B and the second electrode 592, and by a depletion layer extending in the first direction X1 from the boundary between the second side surface 511S2 of the channel portion 511B and the first insulating film 551 of the trench structure T.

[0073] The threshold voltage of the field-effect transistor M1 depends on the width of the channel portion 511B in the first direction X1. Furthermore, the breakdown voltage and threshold voltage of the field-effect transistor M1 depend on the barrier height between the metal of the second electrode 592 and the first semiconductor layer 510.

[0074] In the Schottky junction field-effect transistor M1 shown in Figure 8, the threshold voltage can be easily lowered by reducing the width of the channel portion 511B in the first direction X1, thereby enabling a depletion type transistor. Furthermore, in the Schottky junction field-effect transistor M1, the transconductance g near the threshold voltage is... m This allows for higher performance. Therefore, the Schottky junction field-effect transistor M1 has low losses near the threshold voltage and is suitable for the voltage generation circuit described above.

[0075] Referring to Figures 9 to 15, the semiconductor device 800 of the embodiment will be described.

[0076] As shown in Figure 9, the semiconductor device 800 of the embodiment comprises the semiconductor switching element 300 shown in Figure 1 and a control element 620. The control element 620 includes the field-effect transistor M1 in the voltage generation circuit and / or the semiconductor elements of the gate drive circuit 210 described above.

[0077] The semiconductor device 800 further comprises a support 600. As shown in Figure 10, the semiconductor switching element 300 is mounted on the support 600. As shown in Figure 14, the control element 620 is also mounted on the support 600.

[0078] As shown in Figure 10, the support 600 has a first surface 600A. One direction parallel to the first surface 600A is defined as the X2 axis direction. A direction parallel to the first surface 600A and perpendicular to the X2 axis direction is defined as the Y2 axis direction. A direction perpendicular to both the X2 axis direction and the Y2 axis direction is defined as the Z2 axis direction. The first surface 600A is perpendicular to the Z2 axis direction. For example, the direction along the Y2 axis is defined as the first direction Y2, the direction along the X2 axis is defined as the second direction X2, and the direction along the Z2 axis is defined as the third direction Z2.

[0079] The semiconductor switching element 300 will be described with reference to Figures 10 to 13(b). Figure 11 shows the state in which the second conductive part 622b and the second insulating member 642 have been removed.

[0080] The support 600 has a substrate 601. For example, a silicon substrate can be used as the substrate 601. The semiconductor switching element 300 has a second semiconductor layer 611 provided on the substrate 601 in a third direction Z2. The support 600 may further have an insulating layer 602 provided between the substrate 601 and the second semiconductor layer 611 in the third direction Z2. In this example, the upper surface of the insulating layer 602 becomes the first surface 600A of the support 600. For example, a silicon oxide layer can be used as the insulating layer 602.

[0081] The conductivity type of the second semiconductor layer 611 is the first conductivity type. The first conductivity type is either n-type or p-type. Hereafter, the first conductivity type will be referred to as n-type. The second semiconductor layer 611 is, for example, a silicon layer. The second semiconductor layer 611 may also be a silicon carbide layer or a gallium nitride layer.

[0082] The semiconductor switching element 300 further includes a third electrode 621 and a fourth electrode 622. The third electrode 621 is electrically connected to the drain terminal D of the semiconductor switching element 300 shown in Figure 1. The fourth electrode 622 is electrically connected to the source terminal S of the semiconductor switching element 300 shown in Figure 1. The third electrode 621 and the fourth electrode 622 are located apart from each other in the first direction Y2. The second semiconductor layer 611 is provided between the third electrode 621 and the fourth electrode 622 in the first direction Y2 and is electrically connected to the third electrode 621 and the fourth electrode 622. The third electrode 621, the fourth electrode 622, and the second semiconductor layer 611 extend in the third direction Z2 above the first surface 600A. Up is the direction from the substrate 601 toward the second semiconductor layer 611. Down is the opposite direction to up. Up and down are directions independent of the direction of gravity. This configuration allows for an increase in the density of semiconductor switching elements 300 on the first surface 600A of the support 600, thereby lowering, for example, the on-resistance per unit area.

[0083] The third electrode 621 may include, for example, at least one selected from the group consisting of Al, Cu, Mo, W, Ta, Co, Ru, Ti, and Pt.

[0084] The fourth electrode 622 has a first conductive portion 622a and a second conductive portion 622b. The first conductive portion 622a is in contact with the second semiconductor layer 611. The second semiconductor layer 611 and the first conductive portion 622a form a first Schottky junction S1. The first conductive portion 622a is located between the second semiconductor layer 611 and the second conductive portion 622b in a first direction Y2. The second conductive portion 622b is electrically connected to the first conductive portion 622a.

[0085] The first conductive portion 622a may include, for example, at least one selected from the group consisting of Ti, W, Mo, Ta, Zr, Al, Sn, V, Re, Os, Ir, Pt, Pd, Rh, Ru, Nb, Sr, and Hf. The second conductive portion 622b may include, for example, at least one selected from the group consisting of Al, Cu, Mo, W, Ta, Co, Ru, Ti, and Pt.

[0086] The semiconductor switching element 300 further has a second gate electrode 631. The second gate electrode 631 is electrically connected to the gate terminal G of the semiconductor switching element 300 shown in Figure 1. Multiple second gate electrodes 631 are arranged in a second direction X2. The second gate electrodes 631 face the first Schottky junction S1 in the second direction X2. For example, polycrystalline silicon can be used as the material for the second gate electrodes 631. As shown in Figure 11, the second gate electrodes 631 extend in a third direction Z2. With this configuration, a high-density MOS structure can be provided on the first surface 600A of the support 600, and the channel area per unit area can be increased. This can reduce, for example, the on-resistance. In the semiconductor switching element 300, since no current flows through the support 600, the on-resistance does not increase even if the thickness of the support 600 in the third direction Z2 is increased to increase mechanical strength.

[0087] In the second semiconductor layer 611, the n-type impurity concentration in the region in contact with the third electrode 621 may be higher than that in other regions. This reduces the contact resistance between the third electrode 621 and the second semiconductor layer 611.

[0088] The potential of the second gate electrode 631 allows control of the Schottky barrier thickness (distance in the first direction Y2) in the first Schottky junction S1. When the Schottky barrier is thick, virtually no current flows between the fourth electrode 622 and the second semiconductor layer 611. This results in an off state. In the off state, a depletion layer extends from the first Schottky junction S1 into the second semiconductor layer 611, maintaining the breakdown voltage.

[0089] By controlling the potential of the second gate electrode 631 with the aforementioned gate driver 200, the Schottky barrier is thinned, allowing a tunnel current to flow between the fourth electrode 622 and the second semiconductor layer 611. The flow of this tunnel current results in an ON state.

[0090] The semiconductor switching element 300 may further include a field plate electrode 651, a first insulating member 641, and a second insulating member 642.

[0091] The field plate electrode 651 is provided within a trench formed in the second semiconductor layer 611 and extends in the first direction Y2 and the third direction Z2. The field plate electrode 651 is electrically connected to, for example, the fourth electrode 622. The field plate electrode 651 can mitigate the electric field applied to the second semiconductor layer 611 in the first direction Y2, thereby increasing the breakdown voltage. For example, polycrystalline silicon can be used as the material for the field plate electrode 651.

[0092] The first insulating member 641 is provided between the second gate electrode 631 and the second semiconductor layer 611, between the field plate electrode 651 and the second semiconductor layer 611, between the second gate electrode 631 and the field plate electrode 651, and between adjacent second gate electrodes 631 in the second direction X2, and extends in the third direction Z2. The first insulating member 641 has a first gate insulating portion 641a. The first gate insulating portion 641a is provided between the second gate electrode 631 and the second semiconductor layer 611, between the second gate electrode 631 and the first Schottky junction S1, and between the second gate electrode 631 and the first conductive portion 622a. The second gate electrode 631 faces the first Schottky junction S1 in the second direction X2 via the first gate insulating portion 641a. For example, silicon oxide can be used as the material for the first insulating member 641.

[0093] The second insulating member 642 is provided between the second gate electrode 631 and the second conductive portion 622b, and between the first insulating member 641 and the second conductive portion 622b, and extends in the third direction Z2. For example, silicon oxide can be used as the material for the second insulating member 642.

[0094] As shown in Figure 13(a), the substrate 601 has a second surface 601B located opposite the first surface 600A in the third direction Z2. An interlayer insulating layer (shown by a dashed line) 700 is provided so as to be in contact with the upper part of the second semiconductor layer 611. A first wiring section 300D is provided on the second surface 601B of the substrate 601, which is electrically connected to the third electrode 621. The first wiring section 300D is electrically connected to the drain terminal D of the semiconductor switching element 300. A portion of the first wiring section 300D is located below the semiconductor device 800 and is exposed. A portion of the first wiring section 300D extends parallel to the first direction Y2 and the second direction X2. The substrate 601 is located between the first wiring section 300D and the second semiconductor layer 611.

[0095] In the third direction Z2, a second wiring section 300S can be provided above the second semiconductor layer 611, above the second gate electrode 631, and above the field plate electrode 651 via an interlayer insulating layer. The second wiring section 300S is electrically connected to the second conductive portion 622b of the fourth electrode 622. The second wiring section 300S is electrically connected to the source terminal S of the semiconductor switching element 300. A portion of the second wiring section 300S is located above the semiconductor device 800 and is exposed. A portion of the second wiring section 300S extends parallel to the first direction Y2 and the second direction X2. An interlayer insulating layer 700 is located between a portion of the second wiring section 300S and the second semiconductor layer 611.

[0096] A first gate wiring G1 extending in the second direction X2 is provided on a plurality of second gate electrodes 631 arranged in the second direction X2, and the plurality of second gate electrodes 631 can be electrically connected to the first gate wiring G1. The first gate wiring G1 is electrically connected to the gate terminal G of the semiconductor switching element 300. The first gate wiring G1 is located in the interlayer insulating layer 700. The first gate wiring G1 is located above the semiconductor device 800 and may be exposed. The semiconductor device 800 can be placed, for example, with the second wiring portion 300S in contact with the electrodes of an external circuit. Wiring portions of the semiconductor device 800 other than the second wiring portion 300S are exposed from above the semiconductor device 800 and connected to the external circuit by means of wire bonding or the like. In the semiconductor device 800, the exposed area of ​​the first wiring portion 300D and the second wiring portion 300S, which are the main current paths, that is, the contact area with the external circuit can be increased.

[0097] Alternatively, as shown in Figure 13(b), a second wiring section 300S electrically connected to the second conductive portion 622b of the fourth electrode 622 may be provided on the second surface 601B of the substrate 601. In the third direction Z2, a first wiring section 300D electrically connected to the third electrode 621 via an interlayer insulating layer can be provided above the second semiconductor layer 611, above the second gate electrode 631, and above the field plate electrode 651. A portion of the first wiring section 300D is located above the semiconductor device 800 and is exposed. A portion of the first wiring section 300D extends parallel to the first direction Y2 and the second direction X2. A portion of the second wiring section 300S is located below the semiconductor device 800 and is exposed. A portion of the second wiring section 300S extends parallel to the first direction Y2 and the second direction X2.

[0098] As shown in Figure 9, the area of ​​the region where the semiconductor switching element 300 is provided is larger than the area of ​​the region where the control element 620 is provided. In the region of the semiconductor device 800 where the semiconductor switching element 300 is provided, multiple cell groups (first to fourth cell groups 671 to 674) are provided. A cell group refers to a group of cells of the semiconductor switching element 300 that share the second semiconductor layer 611. In the first direction Y2, the second cell group 672 is located between the first cell group 671 and the fourth cell group 674, and the third cell group 673 is located between the second cell group 672 and the fourth cell group 674. In each cell group, the structures shown in Figures 10 to 12 described above are repeated multiple times in the second direction X2.

[0099] The direction from the third electrode 621 of the first cell group 671 to the fourth electrode 622 of the first cell group 671 is the opposite of the direction from the third electrode 621 of the second cell group 672 to the fourth electrode 622 of the second cell group 672. The direction from the third electrode 621 of the third cell group 673 to the fourth electrode 622 of the third cell group 673 is the opposite of the direction from the third electrode 621 of the fourth cell group 674 to the fourth electrode 622 of the fourth cell group 674. The direction from the third electrode 621 of the first cell group 671 to the fourth electrode 622 of the first cell group 671 is the same as the direction from the third electrode 621 of the third cell group 673 to the fourth electrode 622 of the third cell group 673. The direction from the third electrode 621 of the second cell group 672 to the fourth electrode 622 of the second cell group 672 is the same as the direction from the third electrode 621 of the fourth cell group 674 to the fourth electrode 622 of the fourth cell group 674.

[0100] In the second cell group 672 and the third cell group 673, the third electrode 621 is shared. In the first cell group 671 and the second cell group 672, the fourth electrode 622 is shared. In the third cell group 673 and the fourth cell group 674, the fourth electrode 622 is shared.

[0101] Next, the control element 620 will be described with reference to Figures 14 and 15.

[0102] For example, the control element 620 is provided on the same substrate 601 as the semiconductor switching element 300. The control element 620 is located away from the semiconductor switching element 300 in the XY plane. The control element 620 has a third semiconductor layer 612 provided on the substrate 601 in a third direction Z2. The conductivity type of the third semiconductor layer 612 is the first conductivity type. The material of the third semiconductor layer 612 can be the same material as the second semiconductor layer 611 of the semiconductor switching element 300.

[0103] The control element 620 further comprises a fifth electrode 623 and a sixth electrode 624. The fifth electrode 623 and the sixth electrode 624 are located apart from each other in one direction on the XY plane, for example, in a first direction Y2. A third semiconductor layer 612 is provided between the fifth electrode 623 and the sixth electrode 624 in the first direction Y2 and is electrically connected to the fifth electrode 623 and the sixth electrode 624. The fifth electrode 623, the sixth electrode 624, and the third semiconductor layer 612 extend in a third direction Z2 above the first surface 600A of the support 600.

[0104] The sixth electrode 624 has a third conductive portion 624a and a fourth conductive portion 624b. The third conductive portion 624a is in contact with the third semiconductor layer 612. The third semiconductor layer 612 and the third conductive portion 624a form a second Schottky junction S2. The third conductive portion 624a is located between the third semiconductor layer 612 and the fourth conductive portion 624b in the first direction Y2. The fourth conductive portion 624b is electrically connected to the third conductive portion 624a.

[0105] The material of the fifth electrode 623 can be the same as the material of the third electrode 621 of the semiconductor switching element 300. The material of the third conductive part 624a can be the same as the material of the first conductive part 622a of the semiconductor switching element 300. The material of the fourth conductive part 624b can be the same as the material of the second conductive part 622b of the semiconductor switching element 300.

[0106] The control element 620 further has a third gate electrode 632. Multiple third gate electrodes 632 are aligned in one direction on the XY plane, for example, in a second direction X2. The third gate electrodes 632 face the second Schottky junction S2 in the second direction X2. The third gate electrodes 632 extend in a third direction Z2. The material of the third gate electrodes 632 can be the same material as the second gate electrode 631 of the semiconductor switching element 300.

[0107] The potential of the third gate electrode 632 controls the thickness of the Schottky barrier (distance in the first direction Y2) in the second Schottky junction S2. When the Schottky barrier is thick, virtually no current flows between the sixth electrode 624 and the third semiconductor layer 612. This results in an off state. By controlling the potential of the third gate electrode 632, the Schottky barrier becomes thinner, and a tunnel current, for example, flows between the sixth electrode 624 and the third semiconductor layer 612. The flow of this tunnel current results in an on state.

[0108] The control element 620 may further include a third insulating member 643 and a fourth insulating member 644.

[0109] The third insulating member 643 is provided between the third gate electrode 632 and the third semiconductor layer 612 and extends in the third direction Z2. As shown in Figure 15, the third insulating member 643 has a second gate insulating portion 643a. The second gate insulating portion 643a is provided between the third gate electrode 632 and the third semiconductor layer 612, between the third gate electrode 632 and the second Schottky junction S2, and between the third gate electrode 632 and the third conductive portion 624a. The third gate electrode 632 faces the second Schottky junction S2 in the second direction X2 via the second gate insulating portion 643a. The material of the third insulating member 643 can be the same as the material of the first insulating member 641 of the semiconductor switching element 300.

[0110] The fourth insulating member 644 is provided between the third gate electrode 632 and the fourth conductive part 624b, and between the third insulating member 643 and the fourth conductive part 624b, and extends in the third direction Z2. The material of the fourth insulating member 644 can be the same as the material of the second insulating member 642 of the semiconductor switching element 300.

[0111] If the control element 620 is the aforementioned field-effect transistor M1, then the fifth electrode 623 of the control element 620 is the drain terminal D of the field-effect transistor M1. M1 The sixth electrode 624 of the control element 620 is electrically connected to the source terminal S of the field-effect transistor M1. M1 It is electrically connected to it.

[0112] When the control element 620 is the first semiconductor element 211 and the second semiconductor element 212 of the gate drive circuit 210, the fifth electrode 623 is electrically connected to the drain terminals of the first semiconductor element 211 and the second semiconductor element 212, and the sixth electrode 624 is electrically connected to the source terminals of the first semiconductor element 211 and the second semiconductor element 212.

[0113] As shown in Figure 14, the third gate electrode 632 of the control element 620 can be electrically connected to a second gate wiring G2 that is provided on the third gate electrode 632 and extends in the second direction X2. If the control element 620 is a field-effect transistor M1, the second gate wiring G2 is connected to the gate terminal G of the field-effect transistor M1. M1 It is electrically connected to the third semiconductor layer 612, and the second gate wiring G2 is provided in the interlayer insulating layer.

[0114] When the control element 620 is the first semiconductor element 211 and the second semiconductor element 212 of the gate drive circuit 210, the second gate wiring G2 is electrically connected to the gate terminals of the first semiconductor element 211 and the second semiconductor element 212.

[0115] According to this embodiment, the semiconductor switching element 300 and the control element 620 can be formed using the same process simply by changing the mask patterns used during film deposition and etching for forming each component of the semiconductor switching element 300 and the control element 620. For example, the second semiconductor layer 611 and the third semiconductor layer 612 can be formed on the same substrate 601, and the semiconductor switching element 300 and the control element 620 can be configured as a single chip. This makes it possible to integrate a power semiconductor device with a built-in control element 620 into a single chip at a low cost. When the semiconductor switching element 300 and the control element 620 are integrated into a single chip, it becomes possible to reduce the parasitic inductance of the wiring that electrically connects the semiconductor switching element 300 and the control element 620.

[0116] On the substrate 601, a fifth insulating member 660 can be provided between the semiconductor switching element 300 and the control element 620, as shown in Figure 9. The fifth insulating member 660 can also be provided between multiple control elements 620. For example, silicon oxide can be used as the material for the fifth insulating member 660.

[0117] Alternatively, the second semiconductor layer 611 and the third semiconductor layer 612 may be formed on the same substrate 601, and then separated into a semiconductor switching element 300 chip and a control element 620 chip. In that case, the semiconductor switching element 300 chip and the control element 620 chip can be mounted on the same wiring board and packaged.

[0118] The voltage applied between the third electrode 621 and the fourth electrode 622 of the semiconductor switching element 300 is higher than the voltage applied between the fifth electrode 623 and the sixth electrode 624 of the control element 620. Therefore, in order to increase the breakdown voltage of the semiconductor switching element 300, it is preferable that the thickness of the second semiconductor layer 611 of the semiconductor switching element 300 in the first direction Y2 is greater than the thickness of the third semiconductor layer 612 of the control element 620 in the first direction Y2.

[0119] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of Symbols]

[0120] 10, 10A~10D…Voltage generation circuit, 11…First terminal, 12…Second terminal, 20…Buffer circuit, 30…Series-parallel switching circuit, 100…Semiconductor module, 200…Gate driver, 210…Gate drive circuit, 220…Photocoupler, 300…Semiconductor switching element, M1…Depletion-type field-effect transistor

Claims

1. First terminal and The second terminal and, Depletion-type field-effect transistors, A first diode connected between the first terminal and the field-effect transistor, A first capacitor connected between the field-effect transistor and ground, Equipped with, The anode terminal of the first diode is connected to the first terminal, and the cathode terminal of the first diode is connected to the drain terminal of the field-effect transistor. The source terminal of the field-effect transistor is connected to the second terminal and one end of the first capacitor. A voltage generating circuit in which the gate terminal of the field-effect transistor is connected to the other end of the first capacitor.

2. It also includes a Zener diode, The voltage generating circuit according to claim 1, wherein the anode terminal of the Zener diode is connected to the other end of the first capacitor, and the cathode terminal of the Zener diode is connected to the source terminal and the second terminal of the field-effect transistor.

3. The system further comprises a second capacitor connected in series with the first capacitor, The voltage generating circuit according to claim 1 or 2, wherein the gate terminal of the field-effect transistor is connected between the first capacitor and the second capacitor.

4. The field-effect transistor further comprises a buffer circuit connected between the gate terminal and the source terminal, The voltage generation circuit according to claim 1 or 2, wherein the buffer circuit changes the potential of the gate terminal to a potential lower than the threshold voltage of the field-effect transistor when the potential of the source terminal exceeds a first threshold voltage.

5. A third capacitor connected to the second terminal, A series-parallel switching circuit capable of switching between a first state in which the first capacitor and the third capacitor are connected in parallel with respect to the field-effect transistor, and a second state in which the first capacitor and the third capacitor are connected in series with respect to the field-effect transistor, The voltage generating circuit according to claim 1, further comprising:

6. The aforementioned field-effect transistor is First electrode and A first semiconductor layer of a first conductivity type provided on the first electrode, the first semiconductor layer having a mesa portion, A second electrode located in a recess provided in the upper part of the mesa portion, In the first direction, the first gate electrode adjacent to the mesa portion, An insulating film is provided between the mesa portion and the first gate electrode, It has, The aforementioned mesa portion is In the first direction, the first surface facing the first gate electrode via the insulating film, A second surface located opposite the first surface in the first direction, and in contact with the second electrode, A voltage generating circuit according to claim 1 or 2, having the following features.

7. Gate drive circuit and The voltage generating circuit according to claim 1, wherein the second terminal is connected to the gate drive circuit and supplies voltage to the gate drive circuit, A gate driver equipped with the following features.

8. The gate driver according to claim 7, Semiconductor switching elements and Equipped with, A voltage across the semiconductor switching element is applied between the first terminal of the voltage generation circuit and the other end of the first capacitor. The output terminal of the gate drive circuit is connected to the gate terminal of the semiconductor switching element, forming a semiconductor module.

9. The semiconductor switching element and the field-effect transistor of the voltage generation circuit are provided on a support having a first surface. The semiconductor switching element is The third electrode and A fourth electrode located away from the third electrode in a second direction along the first surface, A second semiconductor layer is provided between the third electrode and the fourth electrode in the second direction, and forms a first Schottky junction with the fourth electrode, In a third direction intersecting the second direction along the first surface, a second gate electrode facing the first Schottky junction and It has, The aforementioned field-effect transistor is The fifth electrode and, A sixth electrode located away from the fifth electrode in the second direction, A third semiconductor layer is provided between the fifth electrode and the sixth electrode in the second direction, and forms a second Schottky junction with the sixth electrode, In the third direction, a third gate electrode facing the second Schottky junction, A semiconductor module according to claim 8, having the following features.

Images