Input capacitance measuring circuit and method of manufacturing semiconductor device

Abstract

Provided is an input capacitance measuring circuit that improves the accuracy of measuring the input capacitance of a semiconductor device. Also provided is a method of manufacturing a semiconductor device. The input capacitance measuring circuit includes a transformer, a first capacitor, a second capacitor, and a third capacitor. One end of a primary winding of the transformer is configured to be connectable to an anode of the semiconductor device. The other end of the primary winding of the transformer is connected to one end of the first capacitor. One end of a secondary winding of the transformer is configured to be connectable to a cathode of the semiconductor device. The other end of the secondary winding of the transformer is connected to one end of the second capacitor. One end of the third capacitor is configured to be connectable to the cathode of the semiconductor device. The other end of the first capacitor, the other end of the second capacitor, and the other end of the third capacitor are electrically connected to each other.

Description

TECHNICAL FIELD

[0001] The present application relates to an input capacitance measuring circuit and a manufacturing method of a semiconductor device. BACKGROUND

[0002] A method of measuring a parasitic capacitance of a semiconductor device is disclosed in Patent Literature 1. In the circuit for measuring an input capacitance of a semiconductor device in Patent Literature 1, a bypass capacitor is provided between a collector electrode and an emitter electrode. The capacitance of the bypass capacitor has a sufficiently large value with respect to the parasitic capacitance between the collector and the emitter, and also has a sufficiently large value with respect to the parasitic capacitance between the gate and the collector. Therefore, the measuring circuit is regarded as an equivalent circuit in which the parasitic capacitance between the gate and the collector and the parasitic capacitance between the gate and the emitter are connected in parallel. The input capacitance of the semiconductor device is measured through the equivalent circuit.

[0003] Patent Literature 1: Japanese Patent Application Publication No. 2017-090266

[0004] In the method of measuring the parasitic capacitance described in Patent Literature 1, as the voltage applied between the collector and the emitter becomes larger, the withstand voltage of the bypass capacitor needs to be increased. However, in the case where the electrostatic capacitance of the bypass capacitor is maintained and the withstand voltage thereof is increased, the size of the bypass capacitor becomes larger, and further, the size of the measuring device becomes larger. On the other hand, if the withstand voltage of the bypass capacitor is maintained and the electrostatic capacitance thereof is reduced, the increase in the size thereof is suppressed, but the reduction in the electrostatic capacitance of the bypass capacitor causes an increase in the measurement error of the input capacitance of the semiconductor device. SUMMARY

[0005] The present application is to solve the above-described problem, and an object thereof is to provide an input capacitance measuring circuit that improves the measurement accuracy of the input capacitance of a semiconductor device.

[0006] The input capacitance measuring circuit according to the present application measures an input capacitance of a semiconductor device. The input capacitance measuring circuit has a transformer including a primary wiring and a secondary wiring, a first capacitor, a second capacitor, and a third capacitor. One end of the primary wiring of the transformer is configured to be connectable to an anode of the semiconductor device. The other end of the primary wiring of the transformer is connected to one end of the first capacitor. One end of the secondary wiring of the transformer is configured to be connectable to a cathode of the semiconductor device. The other end of the secondary wiring of the transformer is connected to one end of the second capacitor. One end of the third capacitor is configured to be connectable to the cathode of the semiconductor device. The other end of the first capacitor, the other end of the second capacitor, and the other end of the third capacitor are electrically connected to each other.

[0007] EFFECT OF THE INVENTION

[0008] The input capacitance measurement circuit according to the present application improves the measurement accuracy of the input capacitance of a semiconductor device.

[0009] The objects, features, schemes, and advantages of the present application will become more apparent from the following detailed description and accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 is a circuit diagram showing the structure of the input capacitance measurement system in Embodiment 1.

[0011] Figure 2 is a circuit diagram related to the operation of the input capacitance measurement system with respect to a high-frequency signal.

[0012] Figure 3 is an enlarged circuit diagram of the area enclosed by the broken line in Figure 2 .

[0013] Figure 4 is a further simplified circuit diagram of the circuit diagram shown in Figure 2 .

[0014] Figure 5 is a further simplified circuit diagram of the circuit diagram shown in Figure 4 .

[0015] Figure 6 is a circuit diagram showing the structure of the input capacitance measurement system in Embodiment 2.

[0016] Figure 7 is a circuit diagram related to the operation of the input capacitance measurement system with respect to a high-frequency signal.

[0017] Figure 8 is an enlarged circuit diagram of the area enclosed by the broken line in Figure 7 .

[0018] Figure 9 is a further simplified circuit diagram of the circuit diagram shown in Figure 7 .

[0019] Figure 10 is a further simplified circuit diagram of the circuit diagram shown in Figure 9 .

[0020] Figure 11 is a circuit diagram showing the structure of the input capacitance measurement system in Embodiment 3.

[0021] Figure 12 is a circuit diagram related to the operation of the input capacitance measurement system with respect to a high-frequency signal.

[0022] Figure 13 is a further simplified circuit diagram of the circuit diagram shown in Figure 12 .

[0023] Figure 14 is a circuit diagram showing the structure of the input capacitance measurement system in Embodiment 4.

[0024] Figure 15 is a circuit diagram related to the operation of the input capacitance measurement system for a high frequency signal.

[0025] Figure 16 is a circuit diagram in which the circuit diagram shown in Figure 15 is simplified.

[0026] Figure 17 is a circuit diagram in which the circuit diagram shown in Figure 16 is further simplified.

[0027] Figure 18 is a circuit diagram showing the structure of the input capacitance measurement system in Embodiment 5.

[0028] Figure 19 is a circuit diagram in which a part of the input capacitance measurement circuit in Embodiment 5 is enlarged.

[0029] Figure 20 is a circuit diagram showing the current flowing through the primary wiring and the secondary wiring.

[0030] Figure 21 is a circuit diagram showing the state in which a precision low resistance is connected to both ends of the secondary wiring. DETAILED DESCRIPTION

[0031] <Embodiment 1>

[0032] Figure 1 is a circuit diagram showing the structure of the input capacitance measurement system in Embodiment 1. The input capacitance measurement system has an input capacitance measurement circuit 101 and an LCR meter 20. The input capacitance measurement circuit 101 is a circuit for measuring the input capacitance of a semiconductor device. The semiconductor device includes a switching element. Here, the switching element is an IGBT (Insulated Gate Bipolar Transistor) 30, but is not limited thereto. The switching element can be, for example, a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) or the like. In Figure 1 the circuit diagram, the parasitic capacitances C GC , C GE , and C CE between the gate and the collector of the IGBT 30 are shown by broken lines.

[0033] The input capacitance measuring circuit 101 has a first reactor L1, a second reactor L2, a third reactor L3, a first transformer Tr1, a second transformer Tr2, and first to seventh capacitors C1 to C7. The first to seventh capacitors C1 to C7 are, for example, DC blocking capacitors, but are not limited thereto. It is preferable that the first to seventh capacitors C1 to C7 be high-voltage capacitors.

[0034] The first reactor L1 connects the terminal P1 and the collector electrode of the IGBT 30. The terminal P1 is a terminal for applying a high voltage, i.e., a power supply voltage V CC , of a direct current. The first reactor L1 cuts off a high-frequency signal.

[0035] The second reactor L2 connects the gate electrode and the emitter electrode of the IGBT 30. The second reactor L2 cuts off a high-frequency signal.

[0036] The third reactor L3 connects the emitter electrode of the IGBT 30 and the power supply GND 11. GND is a ground. The third reactor L3 cuts off a high-frequency signal. That is, the third reactor L3 prevents a current accompanying a high-frequency signal from flowing from the emitter electrode to the power supply GND 11.

[0037] The first transformer Tr1 includes a primary wiring A11 and a secondary wiring A12. The second transformer Tr2 includes a primary wiring A21 and a secondary wiring A22. The primary wirings A11, A21 each include a primary coil, and the secondary wirings A12, A22 each include a secondary coil. In Figure 1 , a dot added to each of the primary wirings A11, A21 and the secondary wirings A12, A22 indicates a polarity. Hereinafter, a terminal on the side to which the dot is added will be referred to as a dot-side electrode. A terminal on the opposite side to the dot-side electrode will be referred to as an opposite-side electrode. The second transformer Tr2 is also referred to as a current signal generating transformer.

[0038] The dot-side electrode of the primary wiring A11 of the first transformer Tr1, i.e., one end of the primary wiring A11, is connected to the collector electrode of the IGBT 30.

[0039] The opposite-side electrode of the primary wiring A11 of the first transformer Tr1, i.e., the other end of the primary wiring A11, is connected to one end of the first capacitor C1.

[0040] The opposite-side electrode of the secondary wiring A12 of the first transformer Tr1, i.e., one end of the secondary wiring A12, is connected to the emitter electrode of the IGBT 30.

[0041] The dot-side electrode of the secondary wiring A12 of the first transformer Tr1, i.e., the other end of the secondary wiring A12, is connected to one end of the second capacitor C2.

[0042] One end of the third capacitor C3 is connected to the emitter electrode of the IGBT 30.

[0043] The other end of the first capacitor C1, the other end of the second capacitor C2, and the other end of the third capacitor C3 are electrically connected to each other, and they are at the same potential.

[0044] The opposite side electrode of the primary winding A21 of the second transformer Tr2, i.e., one end of the primary winding A21, is connected to the gate electrode of the IGBT 30.

[0045] The opposite side electrode of the secondary winding A22 of the second transformer Tr2, i.e., one end of the secondary winding A22, is electrically connected to the other end of the first capacitor C1, the other end of the second capacitor C2, and the other end of the third capacitor C3. The one end of the secondary winding A22 of the second transformer Tr2 is connected to, for example, a connection point at which the other end of the first capacitor C1, the other end of the second capacitor C2, and the other end of the third capacitor C3 are connected to each other. In other words, at the connection point, the other end of the first capacitor C1, the other end of the second capacitor C2, the other end of the third capacitor C3, and the opposite side electrode of the secondary winding A22 of the second transformer Tr2 are connected to each other.

[0046] The number of turns of the primary coil of the first transformer Tr1 is the same as the number of turns of the secondary coil of the first transformer Tr1. The number of turns of the primary winding A21 of the second transformer Tr2 is the same as the number of turns of the secondary winding A22 of the second transformer Tr2. The primary winding A11 and the secondary winding A12 of the first transformer Tr1 are tightly coupled to each other, and no magnetic flux leakage occurs. The primary winding A21 and the secondary winding A22 of the second transformer Tr2 are tightly coupled to each other, and no magnetic flux leakage occurs.

[0047] The withstand voltage of the first capacitor C1 and the second capacitor C2 is sufficiently higher than the power supply voltage V CC The static capacitance of the first capacitor C1 is the same as the static capacitance of the second capacitor C2.

[0048] The LCR meter 20 includes a signal generator 21, a vector voltmeter 22, a current-voltage conversion circuit 23 (hereinafter, referred to as an I-V conversion circuit 23), and a signal GND 24. The LCR meter 20 can also be an impedance analyzer.

[0049] The signal application terminal Hc of the signal generator 21 is connected to the point-side electrode of the primary winding A21 of the 2nd transformer Tr2, i.e., the other end of the primary winding A21, via the 4th capacitor C4. Since the opposite-side electrode of the primary winding A21 of the 2nd transformer Tr2 is connected to the gate electrode of the IGBT 30, the signal generator 21 is connected to the gate electrode of the IGBT 30 via the 4th capacitor C4 and the primary winding A21 of the 2nd transformer Tr2.

[0050] The high-side potential measurement terminal Hp of the vector voltage meter 22 is connected to the gate electrode of the IGBT 30 via the 5th capacitor C5. The low-side potential measurement terminal Lp of the vector voltage meter 22 is connected to the emitter electrode of the IGBT 30 via the 6th capacitor C6. That is, the vector voltage meter 22 is connected to the gate electrode and the emitter electrode of the IGBT 30.

[0051] The current measurement terminal Lc of the I-V conversion circuit 23 is connected to the point-side electrode of the secondary winding A22 of the 2nd transformer Tr2 via the 7th capacitor C7. The I-V conversion circuit 23 is connected to the protection terminal G of the signal GND 24 via the secondary winding A22 of the 2nd transformer Tr2 and the above-mentioned connection point.

[0052] The protection terminal G of the signal GND 24 is connected to the other end of the 1st capacitor C1, the other end of the 2nd capacitor C2, the other end of the 3rd capacitor C3, and the opposite-side electrode of the secondary winding A22 of the 2nd transformer Tr2. The protection terminal G is connected to, for example, the above-mentioned connection point.

[0053] Figure 1 The connection structure in the input capacitance measurement state is shown, and thus the input capacitance measurement circuit 101 is connected to the IGBT 30, but the input capacitance measurement circuit 101 can not be connected to the IGBT 30 in a state other than the input capacitance measurement state. For example, the input capacitance measurement circuit 101 can have a terminal (not shown) that can be connected to the IGBT 30. For example, a terminal for connecting the point-side electrode of the primary winding A11 of the 1st transformer Tr1 and the collector electrode of the IGBT 30 can be provided. A terminal for connecting the opposite-side electrode of the secondary winding A12 of the 1st transformer Tr1 and the emitter electrode of the IGBT 30 can be provided. A terminal for connecting one end of the 3rd capacitor C3 and the emitter electrode of the IGBT 30 can be provided. A terminal for connecting the opposite-side electrode of the primary winding A21 of the 2nd transformer Tr2 and the gate electrode of the IGBT 30 can be provided. The same applies to the connection of the input capacitance measurement circuit 101 and the LCR meter 20, and for example, the input capacitance measurement circuit 101 can have a terminal (not shown) for connection to the LCR meter 20 in a state other than the input capacitance measurement state.

[0054] Next, the operation of the input capacitance measurement system with respect to the direct current power supply is described. Since the gate-emitter electrode of the IGBT 30 is short-circuited by the 2nd reactor L2, the IGBT 30 is in an off state. The power supply voltage V CC is applied between the collector electrode and the emitter electrode of the IGBT 30 via the 1st reactor LI and the 3rd reactor L3. The collector electrode is also connected to the dot side electrode of the primary winding Al l of the 1st transformer Trl, but since the 1st capacitor CI is connected to the opposite side electrode of the primary winding Al l of the 1st transformer Trl, the power supply voltage V CC is not applied between the dot side electrode and the opposite side electrode of the primary winding Al l of the 1st transformer Trl. In other words, the voltage is not applied to both ends of the primary winding Al l of the 1st transformer Trl.

[0055] Next, as the input capacitance measurement method in Embodiment 1, the operation of the input capacitance measurement system with respect to a high frequency signal is described. The high frequency signal is, for example, a signal of 100 kHz. With respect to the high frequency signal, the impedance of each of the 1st reactor LI, the 2nd reactor L2, and the 3rd reactor L3 increases, and each of the reactors is considered to be in an open circuit state. In addition, since 4-terminal measurement is applied, the 4th capacitor C4 to the 7th capacitor C7 are considered to be in a short circuit state regardless of the impedance of the cables and the capacitors connected to the signal application terminal Hc, the high side potential measurement terminal Hp, the low side potential measurement terminal Lp, and the current measurement terminal Lc, respectively. In order to simplify the description of the operation with respect to the high frequency signal, in the following, the 1st reactor LI to the 3rd reactor L3 are considered to be in an open circuit state, and the 4th capacitor C4 to the 7th capacitor C7 are considered to be in a short circuit state, and the operation of the input capacitance measurement system is described.

[0056] Figure 2 is a circuit diagram related to the operation of the input capacitance measurement system with respect to a high frequency signal. In Figure 2 , the illustration of the 1st reactor LI to the 3rd reactor L3, the 4th capacitor C4 to the 7th capacitor C7, the terminal Pl, and the power supply GND 11 is omitted. Figure 3 is an enlarged circuit diagram of the region Ql enclosed by the broken line in Figure 2

[0057] The collector electrode of the IGBT 30 is connected to the signal GND 24 via the primary winding Al l of the 1st transformer Trl and the 1st capacitor CI. The current I c flows from the collector electrode to the signal GND 24 via the primary winding Al l of the 1st transformer Trl and the 1st capacitor CI.

[0058] ​The emitter electrode of the IGBT 30 is connected to two paths in addition to the path connected to the low-side potential measuring terminal Lp of the vector voltmeter 22. One of the paths is connected to the signal GND 24 via the third capacitor C3. The other path is connected to the signal GND 24 via the secondary winding A12 of the first transformer Trl and the second capacitor C2. The current IE flowing from the emitter electrode is divided into a current I E1 and a current I E2 . The current I E1 flows into the signal GND 24 via the third capacitor C3. The current I E2 flows into the signal GND 24 via the secondary winding A12 of the first transformer Trl and the second capacitor C2.

[0059] Since the number of turns of the primary winding of the first transformer Trl is the same as the number of turns of the secondary winding, the voltage VI generated across the primary winding Al l is the same as the voltage V2 generated across the secondary winding A12 (VI = V2).

[0060] The first transformer Trl satisfies the following equation (1) in its characteristics.

[0061] [Mathematical Equation 1]

[0062] VI x Ic = V2 x I E2 (1)

[0063] Therefore, the current I C flowing through the primary winding Al l is the same as the current I E2 flowing through the secondary winding A12 (I C = I E2 ).

[0064] Since the electrostatic capacitance of the first capacitor Cl is the same as the electrostatic capacitance of the second capacitor C2, the voltage generated across the first capacitor Cl is the same as the voltage generated across the second capacitor C2.

[0065] For the above reasons, the voltage generated between the signal GND 24 and the emitter electrode is the same as the voltage generated between the signal GND 24 and the collector electrode. That is, the collector electrode is at the same potential as the emitter electrode. Therefore, the circuit diagram shown in Fig. 1 is further simplified. Figure 2

[0066] Figure 4 is a circuit diagram further simplified from the circuit diagram shown in Fig. 1. Figure 2 Figure 4 ​​The impedance Z shown corresponds to the impedance between the collector electrode and signal GND 24, and between the emitter electrode and signal GND 24. In other words, impedance Z includes the impedances of the first transformer Tr1, the first capacitor C1, the second capacitor C2, and the third capacitor C3. Figure 4 In the process, the position of the vector voltmeter 22 of the LCR measuring instrument 20 is moved to the gate-emitter space of the IGBT 30.

[0067] Since the collector electrode is at the same potential as the emitter electrode, therefore, in the parasitic capacitance C CE No current flowed. Therefore, further simplification is needed. Figure 4 The circuit diagram shown.

[0068] Figure 5 It is Figure 4 The circuit diagram shown is a further simplified circuit diagram. The IGBT30 in input capacitance measurement state and the parasitic capacitance C... GE and parasitic capacitance C GC Circuits connected in parallel are equivalent.

[0069] The signal current I is generated by the high-frequency signal output from the signal application terminal Hc of the signal generator 21. G The fluid flows into the parasitic capacitance C via the primary wiring A21 of the second transformer Tr2. GE and parasitic capacitance C GC A parallel circuit is formed. In this parallel circuit, the signal current I... G It is divided into flows through parasitic capacitance C GE Current I GE and the parasitic capacitance C GC Current I GC Then, the current I... GE and current I GC The signal current I after merging G It flows into signal GND 24 through impedance Z.

[0070] Signal current I G The signal current I flows through the primary wiring A21 of the second transformer Tr2, and thus flows through the secondary wiring A22 of the second transformer Tr2, which is the same as the signal current I flowing through the primary wiring A21. G Current I with the same current value G The current I G The signal GND24 flows into the current measuring terminal Lc via the secondary wiring A22 of the second transformer Tr2. The IV conversion circuit 23 measures the current I... G The current value and phase of ' were measured.

[0071] Vector voltmeter 22 pairs of current I G The parasitic capacitance C flows throughGC and the voltage and its phase across the parallel circuit of the parasitic capacitance C GE are measured.

[0072] The LCR meter 20 measures the input capacitance C G and the absolute value of its voltage (e.g., the ratio of the absolute values), the phase difference, based on the current I iss (= C GC + C GE ).

[0073] As described above, the input capacitance measuring circuit 101 in Embodiment 1 measures the input capacitance of the semiconductor device. The input capacitance measuring circuit 101 has the 1st transformer Tr1 including the primary wiring Al l and the secondary wiring A12, the 1st capacitor Cl, the 2nd capacitor C2, and the 3rd capacitor C3. One end of the primary wiring Al l of the 1st transformer Tr1 is configured to be connectable to the anode of the semiconductor device. The other end of the primary wiring Al l of the 1st transformer Tr1 is connected to one end of the 1st capacitor Cl. One end of the secondary wiring A12 of the 1st transformer Tr1 is configured to be connectable to the cathode of the semiconductor device. The other end of the secondary wiring A12 of the 1st transformer Tr1 is connected to one end of the 2nd capacitor C2. One end of the 3rd capacitor C3 is configured to be connectable to the cathode of the semiconductor device. The other end of the 1st capacitor Cl, the other end of the 2nd capacitor C2, and the other end of the 3rd capacitor C3 are electrically connected to each other. In the case where the semiconductor device is the IGBT 30, the anode is the collector electrode, and the cathode is the emitter electrode. In the case where the semiconductor device is the MOSFET, the anode is the drain electrode, and the cathode is the source electrode. Each electrode can also be referred to as a terminal.

[0074] The withstand voltage of the 1st capacitor Cl and the withstand voltage of the 2nd capacitor C2 can be higher than the power supply voltage V CC . The electrostatic capacitances of the 1st capacitor Cl and the 2nd capacitor C2 can be small as long as they are the same. The sizes of the 1st capacitor Cl and the 2nd capacitor C2 can be small. The input capacitance measuring circuit 101 suppresses an increase in the sizes of the 1st capacitor Cl and the 2nd capacitor C2 and improves the measurement accuracy of the input capacitance. In particular, even in the case where the specifications of the semiconductor device are for high voltage, the input capacitance measuring circuit 101 of Embodiment 1 can measure the input capacitance of the semiconductor device with high accuracy.

[0075] The input capacitance measuring circuit 101 in Embodiment 1 is not affected at all by the bypass capacitor described in Patent Literature 1. The input capacitance measuring circuit 101 can obtain the true value of the input capacitance, not an approximate value as in the conventional method. Therefore, the measurement accuracy of the input capacitance is improved compared to the conventional method.

[0076] The input capacitance measurement method of the semiconductor device based on the input capacitance measuring circuit 101 is applied to one process of a manufacturing process of the semiconductor device. That is, the input capacitance measurement method in Embodiment 1 is a manufacturing method of a semiconductor device. The input capacitance measurement method in each of the embodiments shown later is also similarly a manufacturing method of a semiconductor device. The form of the semiconductor device at the time of input capacitance measurement can be any of a wafer state in which a plurality of chips including switching elements are arranged on a wafer, a chip state in which the chips are individually cut, and a module state in which the chips are packaged in a case. The form of the semiconductor device at the time of input capacitance measurement can also be a state of a finished product. According to the manufacturing method of a semiconductor device, it is possible to highly accurately test that the input capacitance satisfies a specification and that the characteristics of the input capacitance do not vary in a manufacturing process of a semiconductor device.

[0077] <Embodiment 2>

[0078] In Embodiment 2, the same reference numerals are attached to the same structural elements as those in Embodiment 1, and detailed description thereof is omitted.

[0079] Figure 6 is a circuit diagram showing the structure of an input capacitance measuring system in Embodiment 2. The input capacitance measuring system has an input capacitance measuring circuit 102 and an LCR meter 20.

[0080] The input capacitance measuring circuit 102 has a first reactor L1 to a third reactor L3, a first transformer Tr1, and a first capacitor C1 to a sixth capacitor C6. The input capacitance measuring circuit 102 in Embodiment 2 is different from the input capacitance measuring circuit 101 in Embodiment 1 in that the input capacitance measuring circuit 102 in Embodiment 2 does not have a second transformer Tr2 and a seventh capacitor C7. In addition, in Embodiment 2, the connection structure of the input capacitance measuring circuit 102 and the LCR meter 20 is different from the connection structure of Embodiment 1.

[0081] The number of turns of the primary coil of the first transformer Tr1 is the same as the number of turns of the secondary coil of the first transformer Tr1. The withstand voltage of the first capacitor C1 and the second capacitor C2 is sufficiently higher than the power supply voltage V CC The electrostatic capacitance of the first capacitor C1 is the same as the electrostatic capacitance of the second capacitor C2.

[0082] The signal application terminal Hc of the signal generator 21 is connected to the gate electrode of the IGBT 30 via the fourth capacitor C4.

[0083] The high-side potential measuring terminal Hp of the vector voltmeter 22 is connected to the gate electrode of the IGBT 30 via the 5th capacitor C5. The low-side potential measuring terminal Lp of the vector voltmeter 22 is connected to the emitter electrode of the IGBT 30 via the 6th capacitor C6. That is, the vector voltmeter 22 is connected to the gate electrode and the emitter electrode of the IGBT 30.

[0084] The current measuring terminal Lc of the I-V conversion circuit 23 is connected to the other end of the 1st capacitor Cl, the other end of the 2nd capacitor C2, and the other end of the 3rd capacitor C3. The current measuring terminal Lc is connected to, for example, a connection point at which the other end of the 1st capacitor Cl, the other end of the 2nd capacitor C2, and the other end of the 3rd capacitor C3 are connected to each other.

[0085] The protection terminal G of the signal GND 24 is in an open-circuit state.

[0086] Next, the operation of the input capacitance measuring system with respect to a direct-current power supply is described. Since the gate-emitter of the IGBT 30 is short-circuited by the 2nd reactor L2, the IGBT 30 is in an off state. The power supply voltage V CC is applied between the collector electrode and the emitter electrode of the IGBT 30 via the 1st reactor LI and the 3rd reactor L3. The collector electrode is also connected to the dot-side electrode of the primary winding Al l of the 1st transformer Trl, but since the 1st capacitor Cl is connected to the opposite-side electrode of the primary winding Al l of the 1st transformer Trl, the power supply voltage V CC is not applied between the dot-side electrode and the opposite-side electrode of the primary winding Al l of the 1st transformer Trl. In other words, no voltage is applied to the both ends of the primary winding Al l of the 1st transformer Trl.

[0087] Next, as the input capacitance measurement method in Embodiment 2, the operation of the input capacitance measuring system with respect to a high-frequency signal is described. As in Embodiment 1, in order to simplify the description of the operation with respect to a high-frequency signal, the 1st to 3rd reactors LI to L3 are regarded as being in an open-circuit state, the 4th to 6th capacitors C4 to C6 are regarded as being in a short-circuit state, and the operation of the input capacitance measuring system is described.

[0088] Figure 7 is a circuit diagram related to the operation of the input capacitance measuring system with respect to a high-frequency signal. In Figure 7 , the 1st to 3rd reactors LI to L3, the 4th to 6th capacitors C4 to C6, the terminal Pl, and the power supply GND 11 are omitted. In addition, in Figure 7 , the positions of the signal generator 21, the vector voltmeter 22, and the I-V conversion circuit 23 of the LCR meter 20 are moved to positions suitable for the operation description.

[0089] Figure 8 Is Figure 7 The amplifier circuit diagram for region Q2, enclosed by the dashed line. The current IE flowing from the emitter electrode is divided into current I... E1 and current I E2 Current I E1 The current flows into the current measuring terminal Lc via the third capacitor C3. Current I E2 The current flows into the current measuring terminal Lc via the secondary wiring A12 of the first transformer Tr1 and the second capacitor C2. Current I E2 At point a, the current I E1 The current flows into the current measuring terminal Lc. The current I flowing out of the collector electrode... c The current flows into the current measuring terminal Lc via the primary wiring A11 of the first transformer Tr1 and the first capacitor C1. More specifically, the current I... c At point b, the current I E2 The currents converge at point a with current I. E1 The current converges and flows into the current measuring terminal Lc. That is, the current I... E1 Current I E2 and current I c The current flows into the IV converter circuit 23. Current IE and current I... E1 Current I E2 and current I c It satisfies the following equation (2).

[0090] [Mathematical Expression 2]

[0091] I E1 +I E2 +Ic=I E +Ic (2)

[0092] As described in Embodiment 1, the collector electrode of the IGBT 30 is at the same potential as the emitter electrode. Therefore, this further simplifies... Figure 7 The circuit diagram shown.

[0093] Figure 9 It is Figure 7 The circuit diagram shown is a further simplified version. Since the collector and emitter electrodes are at the same potential, they are short-circuited. Figure 9 The impedance Z shown corresponds to the impedance between the collector electrode and the current measuring terminal Lc, and between the emitter electrode and the current measuring terminal Lc. In other words, impedance Z includes the impedances of the first transformer Tr1, the first capacitor C1, the second capacitor C2, and the third capacitor C3.

[0094] Since the collector electrode is at the same potential as the emitter electrode, therefore, in the parasitic capacitance C CENo current flows. Thus, further simplification Figure 9 is shown in the circuit diagram.

[0095] Figure 10 is the circuit diagram after further simplification of the circuit diagram shown in FIG. 6. The IGBT 30 in the input capacitance measurement state and the parasitic capacitance C Figure 9 are connected in parallel to each other. GE and the parasitic capacitance C GC are equivalent to each other.

[0096] By a high-frequency signal output from the signal application terminal Hc of the signal generator 21, a signal current flows into the parallel circuit formed by the parasitic capacitance C GE and the parasitic capacitance C GC . In the parallel circuit, the signal current is divided into a current flowing through the parasitic capacitance C GE and a current flowing through the parasitic capacitance C GC . Thereafter, the signal current which is output from the parallel circuit and is combined flows into the current measurement terminal Lc via the impedance Z. The I-V conversion circuit 23 measures the current value and the phase of the signal current.

[0097] The vector voltage meter 22 measures the voltage and the phase across the parallel circuit when the signal current flows through the parallel circuit of the parasitic capacitance C GC and the parasitic capacitance C GE .

[0098] The LCR meter 20 measures the input capacitance C iss (= C GC + C GE ) based on the absolute values and the phase difference of the signal current and the voltage.

[0099] The withstand voltage of the first capacitor C1 and the withstand voltage of the second capacitor C2 can be higher than the power supply voltage V CC . The electrostatic capacitances of the first capacitor C1 and the second capacitor C2 can be small as long as they are the same. The sizes of the first capacitor C1 and the second capacitor C2 can be as small as possible. The input capacitance measurement circuit 102 suppresses an increase in the sizes of the first capacitor C1 and the second capacitor C2, and improves the measurement accuracy of the input capacitance.

[0100] The input capacitance measurement circuit 102 in Embodiment 2 is not affected at all by the bypass capacitor described in Patent Literature 1. Thus, the measurement accuracy of the input capacitance is improved compared with the past.

[0101] <Embodiment 3>

[0102] In Embodiment 3, the same reference numerals are attached to the same structural elements as those in Embodiment 1 or 2, and detailed descriptions thereof are omitted.

[0103] Figure 11 is a circuit diagram showing the configuration of the input capacitance measurement system in Embodiment 3. The input capacitance measurement system has the input capacitance measurement circuit 103 and the LCR meter 20.

[0104] The input capacitance measurement circuit 103 has the 1st to 3rd reactors L1 to L3, the 1st transformer Tr1, and the 1st to 7th capacitors C1 to C7. Compared with the input capacitance measurement circuit 102 of Embodiment 2, the input capacitance measurement circuit 103 in Embodiment 3 has the 7th capacitor C7, and the connection structure of the input capacitance measurement circuit 103 and the LCR meter 20 is different from that of Embodiment 2. The other circuit configuration is the same as that in Embodiment 2.

[0105] The signal application terminal Hc of the signal generator 21 is connected to the collector electrode of the IGBT 30 via the 4th capacitor C4.

[0106] The high-side potential measurement terminal Hp of the vector voltmeter 22 is connected to the gate electrode of the IGBT 30 via the 5th capacitor C5. The low-side potential measurement terminal Lp of the vector voltmeter 22 is connected to the emitter electrode of the IGBT 30 via the 6th capacitor C6. That is, the vector voltmeter 22 is connected to the gate electrode and the emitter electrode of the IGBT 30.

[0107] The current measurement terminal Lc of the I-V conversion circuit 23 is connected to the gate electrode of the IGBT 30 via the 7th capacitor C7.

[0108] The protection terminal G of the signal GND 24 is connected to the other end of the 1st capacitor C1, the other end of the 2nd capacitor C2, and the other end of the 3rd capacitor C3. The current measurement terminal Lc is connected to a connection point at which the other ends of the 1st to 3rd capacitors C1 to C3 are connected to each other.

[0109] Next, the operation of the input capacitance measurement system with respect to the direct-current power supply will be described. Since the gate-emitter of the IGBT 30 is short-circuited by the 2nd reactor L2, the IGBT 30 is in the off state. The power supply voltage V CC is applied between the collector electrode and the emitter electrode of the IGBT 30 via the 1st and 3rd reactors L1 and L3. The collector electrode is also connected to the dot electrode of the primary winding Al l of the 1st transformer Tr1, but since the 1st capacitor C1 is connected to the opposite-side electrode of the primary winding Al l of the 1st transformer Tr1, the power supply voltage V CCis cut. In other words, no voltage is applied between the two ends of the primary winding Al l of the first transformer Trl, namely between the point-side electrode and the opposite-side electrode.

[0110] Next, as the input capacitance measurement method in Embodiment 3, the operation of the input capacitance measurement system with respect to the high-frequency signal is described. As with Embodiment 1 or 2, in order to simplify the description of the operation with respect to the high-frequency signal, the first to third reactors Ll to L3 are regarded as open-circuit states, and the fourth to seventh capacitors C4 to C7 are regarded as short-circuit states, and the operation of the input capacitance measurement system is described.

[0111] Figure 12 is a circuit diagram related to the operation of the input capacitance measurement system with respect to the high-frequency signal. In Figure 12 , the illustration of the first to third reactors Ll to L3, the fourth to seventh capacitors C4 to C7, the terminal Pl, and the power source GND 11 is omitted. In addition, in Figure 12 , the positions of the signal generator 21, the vector voltmeter 22, the I-V conversion circuit 23, and the signal GND 24 of the LCR meter 20 are moved to positions suitable for the description of the operation.

[0112] As with Embodiment 1, the collector electrode of the IGBT 30 is at the same potential as the emitter electrode. Therefore, the circuit diagram illustrated in Figure 12 is further simplified.

[0113] Figure 13 is a circuit diagram further simplified from the circuit diagram illustrated in Figure 12 . Since the collector electrode and the emitter electrode are at the same potential as each other, they are short-circuited. Figure 13 The impedance Z illustrated in corresponds to the impedance between the collector electrode and the signal GND 24, and the impedance between the emitter electrode and the signal GND 24. In other words, the impedance Z includes the impedances of the first transformer Trl, the first capacitor Cl, the second capacitor C2, and the third capacitor C3.

[0114] Since the collector electrode is at the same potential as the emitter electrode, the parasitic capacitance C CE does not have a current flowing therethrough. Therefore, the IGBT 30 in the input capacitance measurement state and the circuit in which the parasitic capacitance C GE and the parasitic capacitance C GC are connected in parallel to each other are equivalent.

[0115] A part of the signal current flows into the circuit including the parasitic capacitance C GE and the parasitic capacitance C GCThe parallel circuit is formed. Other signal current flows into impedance Z. The signal current output from the parallel circuit flows into the current measurement terminal Lc. The I-V conversion circuit 23 measures the current value and the phase of the signal current.

[0116] The vector voltmeter 22 measures the voltage across the parallel circuit and the phase thereof when a part of the signal current flows through the parallel circuit of the parasitic capacitance C GC and the parasitic capacitance C GE .

[0117] The LCR meter 20 measures the input capacitance C iss (= C GC + C GE ) based on the absolute values of the signal current and the voltage, the phase difference.

[0118] The first capacitor C1 and the second capacitor C2 can be higher in withstand voltage than the power supply voltage V CC . The electrostatic capacitances of the first capacitor C1 and the second capacitor C2 can be small as long as they are the same. The sizes of the first capacitor C1 and the second capacitor C2 can be small. The input capacitance measurement circuit 103 suppresses an increase in the sizes of the first capacitor C1 and the second capacitor C2, and improves the measurement accuracy of the input capacitance.

[0119] The input capacitance measurement circuit 103 in Embodiment 3 is not affected at all by the bypass capacitor described in Patent Literature 1. Therefore, the measurement accuracy of the input capacitance is improved compared with the past.

[0120] <Embodiment 4>

[0121] In Embodiment 4, the same reference numerals are attached to the same structural elements as those in any one of Embodiments 1 to 3, and detailed description thereof is omitted.

[0122] Figure 14 is a circuit diagram showing the structure of the input capacitance measurement system in Embodiment 4. The input capacitance measurement system has an input capacitance measurement circuit 104 and an LCR meter 20.

[0123] The input capacitance measurement circuit 104 has a first reactor L1 to a third reactor L3, a first transformer Tr1, a second transformer Tr2, a first capacitor C1, a second capacitor C2, and a third capacitor C13 to a sixth capacitor C16. Each of the capacitors is, for example, a DC blocking capacitor, but is not limited thereto.

[0124] The first reactor L1 connects the terminal P1 and the collector electrode of the IGBT 30. The terminal P1 is a terminal for applying a high voltage, that is, a power supply voltage V CC . The first reactor L1 cuts off a high-frequency signal.

[0125] The 2nd reactor L2 connects the gate electrode and the emitter electrode of the IGBT 30. The 2nd reactor L2 cuts off a high-frequency signal.

[0126] The 3rd reactor L3 connects the emitter electrode of the IGBT 30 and the power source GND 11. The 3rd reactor L3 cuts off a high-frequency signal.

[0127] The 1st transformer Tr1 includes a primary wiring A11 and a secondary wiring A12. The 2nd transformer Tr2 includes a primary wiring A21 and a secondary wiring A22. The primary wirings A11, A21 each include a primary coil, and the secondary wirings A12, A22 each include a secondary coil.

[0128] The point-side electrode of the primary wiring A11 of the 1st transformer Tr1 is connected to the point-side electrode of the primary wiring A21 of the 2nd transformer Tr2. That is, one end of the primary wiring A11 of the 1st transformer Tr1 is connected to one end of the primary wiring A21 of the 2nd transformer Tr2.

[0129] The opposite-side electrode of the primary wiring A11 of the 1st transformer Tr1 is connected to the opposite-side electrode of the primary wiring A21 of the 2nd transformer Tr2. That is, the other end of the primary wiring A11 of the 1st transformer Tr1 is connected to the other end of the primary wiring A21 of the 2nd transformer Tr2.

[0130] The point-side electrode of the secondary wiring A12 of the 1st transformer Tr1, that is, one end of the secondary wiring A12 is connected to the collector electrode of the IGBT 30.

[0131] The opposite-side electrode of the secondary wiring A12 of the 1st transformer Tr1, that is, the other end of the secondary wiring A12 is connected to one end of the 1st capacitor C1.

[0132] The other end of the 1st capacitor C1 is connected to the opposite-side electrode of the secondary wiring A12 of the 1st transformer Tr1, that is, the other end of the secondary wiring A12.

[0133] The point-side electrode of the secondary wiring A22 of the 2nd transformer Tr2, that is, one end of the secondary wiring A22 is connected to the emitter electrode of the IGBT 30.

[0134] The opposite-side electrode of the secondary wiring A22 of the 2nd transformer Tr2, that is, the other end of the secondary wiring A22 is connected to one end of the 2nd capacitor C2.

[0135] The other end of the 2nd capacitor C2 is connected to the opposite-side electrode of the primary wiring A21 of the 2nd transformer Tr2, that is, the other end of the primary wiring A21.

[0136] The opposite side electrode of the primary wiring A11 of the first transformer Tr1, the other end of the first capacitor C1, the opposite side electrode of the primary wiring A21 of the second transformer Tr2, and the other end of the second capacitor C2 are electrically connected to each other, and are at the same potential.

[0137] The number of turns of the primary coil of the first transformer Tr1 is the same as the number of turns of the primary coil of the second transformer Tr2. The number of turns of the primary coil of the first transformer Tr1 is the same as the number of turns of the secondary coil of the first transformer Tr1. The number of turns of the primary coil of the second transformer Tr2 is the same as the number of turns of the secondary coil of the second transformer Tr2.

[0138] The withstand voltage of the first capacitor C1 and the second capacitor C2 is sufficiently higher than the power supply voltage V CC The static capacitance of the first capacitor C1 is the same as the static capacitance of the second capacitor C2.

[0139] The signal application terminal Hc of the signal generator 21 is connected to the point side electrode of the primary wiring A11 of the first transformer Tr1 and the point side electrode of the primary wiring A21 of the second transformer Tr2 via the third capacitor C13. That is, the signal application terminal Hc is connected to one end of the primary wiring A11 of the first transformer Tr1 and one end of the primary wiring A21 of the second transformer Tr2.

[0140] The high side potential measurement terminal Hp of the vector voltage meter 22 is connected to the collector electrode of the IGBT 30 via the fourth capacitor C14. The low side potential measurement terminal Lp of the vector voltage meter 22 is connected to the gate electrode of the IGBT 30 via the fifth capacitor C15. That is, the vector voltage meter 22 is connected to the collector electrode and the gate electrode of the IGBT 30.

[0141] The current measurement terminal Lc of the I-V conversion circuit 23 is connected to the gate electrode of the IGBT 30 via the sixth capacitor C16.

[0142] The protection terminal G of the signal GND 24 is connected to the opposite side electrode of the primary wiring A11 of the first transformer Tr1, the other end of the first capacitor C1, the opposite side electrode of the primary wiring A21 of the second transformer Tr2, and the other end of the second capacitor C2.

[0143] Figure 14The connection structure in the input capacitance measurement state is shown, and thus the input capacitance measurement circuit 104 is connected to the IGBT 30, but in a state other than the input capacitance measurement state, the input capacitance measurement circuit 104 can also not be connected to the IGBT 30. The input capacitance measurement circuit 104 can have a terminal (not shown) that can be connected to the IGBT 30. For example, a terminal for connecting the point-side electrode of the secondary winding A12 of the first transformer Tr1 and the collector electrode can be provided. A terminal for connecting the point-side electrode of the secondary winding A22 of the second transformer Tr2 and the emitter electrode can be provided. The same applies to the connection of the input capacitance measurement circuit 104 and the LCR meter 20, and in a state other than the input capacitance measurement state, the input capacitance measurement circuit 104 can have a terminal (not shown) for connection to the LCR meter 20.

[0144] Next, the operation of the input capacitance measurement system with respect to the DC power supply is described. Since the gate-emitter of the IGBT 30 is short-circuited by the second reactor L2, the IGBT 30 is in an off state. The power supply voltage V CC is applied between the collector electrode and the emitter electrode of the IGBT 30 via the first reactor L1 and the third reactor L3. The collector electrode is also connected to the point-side electrode of the secondary winding A12 of the first transformer Tr1, but since the first capacitor C1 is connected to the opposite electrode of the secondary winding A12 of the first transformer Tr1, the power supply voltage V CC is not applied to the both ends of the secondary winding A12 of the first transformer Tr1, that is, between the point-side electrode and the opposite electrode.

[0145] Next, as the input capacitance measurement method in Embodiment 4, the operation of the input capacitance measurement system with respect to the high-frequency signal is described. As in Embodiment 1, in order to simplify the description of the operation with respect to the high-frequency signal, the first to third reactors L1 to L3 are regarded as open-circuit states, the third to sixth capacitors C13 to C16 are regarded as short-circuit states, and the operation of the input capacitance measurement system is described.

[0146] Figure 15 is a circuit diagram related to the operation of the input capacitance measurement system with respect to the high-frequency signal. In Figure 15 , the first to third reactors L1 to L3, the third to sixth capacitors C13 to C16, the terminal P1, and the power supply GND 11 are omitted. In addition, in Figure 15 , the positions of the signal generator 21, the vector voltmeter 22, the I-V conversion circuit 23, and the signal GND 24 of the LCR meter 20 are moved to positions suitable for the operation description.

[0147] A high-frequency signal is output from the signal application terminal Hc of the signal generator 21 to the point-side electrode of the primary wiring A11 of the first transformer Tr1 and the point-side electrode of the primary wiring A21 of the second transformer Tr2.

[0148] The primary wiring A11 of transformer 1 Tr1 and the primary wiring A21 of transformer 2 Tr2 are connected in parallel. The connection point between the opposite electrodes of the primary wiring A11 of transformer 1 Tr1 and the opposite electrodes of the primary wiring A21 of transformer 2 Tr2 is connected to signal GND 24. Therefore, the voltage applied across the primary wiring A11 of transformer 1 Tr1 is the same as the voltage applied across the primary wiring A21 of transformer 2 Tr2. Since the number of turns in the primary coil of transformer 1 Tr1 is the same as the number of turns in the primary coil of transformer 2 Tr2, the signal voltage generated across the secondary wiring A12 of transformer 1 Tr1 is the same as the signal voltage generated across the secondary wiring A22 of transformer 2 Tr2. Since the capacitance of capacitor 1 C1 is the same as the capacitance of capacitor 2 C2, the signal voltage generated between the collector electrode of IGBT 30 and signal GND 24 is the same as the signal voltage generated between the emitter electrode of IGBT 30 and signal GND 24. Therefore, simplification Figure 15 The circuit diagram shown.

[0149] Figure 16 It is Figure 15 The circuit diagram shown is a simplified version. For ease of explanation, signal generator 21 is illustrated as signal generator 21A, which outputs a high-frequency signal to the first transformer Tr1, and signal generator 21B, which outputs to the second transformer Tr2. The collector and emitter electrodes are at the same potential, and no current flows through the parasitic capacitance C. CE Therefore, further simplification is needed. Figure 16 The circuit diagram shown.

[0150] Figure 17 It is Figure 16 The circuit diagram shown is a further simplified circuit diagram. The collector and emitter electrodes are short-circuited. Furthermore, the two signal generators 21A and 21B are again combined and recorded as a single signal generator 21.

[0151] The high-frequency signal output from the signal application terminal Hc of the signal generator 21 causes a signal current to flow into the parasitic capacitance C. GE and parasitic capacitance C GC The resulting parallel circuit. The signal current is divided into currents flowing through the parasitic capacitance C. GE The current flowing through the parasitic capacitance C GCThe current is then measured. Afterwards, the combined signal current output from the parallel circuit flows into the current measuring terminal Lc. The IV conversion circuit 23 measures the current value and phase of the signal current.

[0152] Vector voltmeter 22 pairs the signal current flowing through parasitic capacitance C. GC and parasitic capacitance C GE The voltage and phase at both ends of the parallel circuit are measured.

[0153] The LCR meter 20 measures the input capacitance C based on the absolute value and phase difference of the signal current and voltage. iss (=C GC +C GE ) to be measured.

[0154] The input capacitance measurement circuit 104 in Embodiment 4 achieves the same effect as the input capacitance measurement circuit described in any of Embodiments 1 to 3.

[0155] <Implementation Method 5>

[0156] In Embodiment 5, the same reference numerals are used to label the same structural elements as in Embodiments 1 to 3, and their detailed descriptions are omitted.

[0157] Figure 18 This is a circuit diagram showing the structure of the input capacitance measurement system in Embodiment 5. The input capacitance measurement system includes an input capacitance measurement circuit 105 and an LCR meter 20.

[0158] Figure 19 This is an enlarged circuit diagram of a portion of the input capacitance measurement circuit 105 in Embodiment 5. Figure 19 The circuit diagram around the first transformer Tr1, the first capacitor C1, and the second capacitor C2 is shown.

[0159] In addition to the structure of the input capacitance measuring circuit 101 described in Embodiment 1, the input capacitance measuring circuit 105 also includes a first resistor R1 and a second resistor R2. Other structures are the same as those in Embodiment 1.

[0160] Resistor R1 connects the point-side electrode and the opposite electrode of the primary wiring A11 of transformer Tr1. Resistor R2 connects the point-side electrode and the opposite electrode of the secondary wiring A12 of transformer Tr1. The resistance value of resistor R1 is the same as that of resistor R2. Resistors R1 and R2 are precision low-resistance resistors.

[0161] The following section provides details regarding the current flowing through the primary wiring A11 and secondary wiring A12 of the first transformer Tr1.

[0162] When the number of turns in the primary coil is the same as the number of turns in the secondary coil, the voltage across the primary wiring A11 is always the same as the voltage across the secondary wiring A12. Furthermore, the current flowing through the primary wiring A11 is usually the same as the current flowing through the secondary wiring A12.

[0163] Figure 20 This is a circuit diagram illustrating the current flowing through the primary wiring A11 and the secondary wiring A12. Figure 20 In the circuit diagram, the current I in the primary wiring A11 is... A11 and the current I of the secondary wiring A12 A12 It satisfies the following equation (3).

[0164] [Mathematical Expression 3]

[0165] I A12 =jωM / (jωL) A12 +Z0)×I A11 (3)

[0166] Here, M represents mutual inductance, L A12 This represents the self-inductance of the secondary wiring A12 when the primary wiring A11 is open.

[0167] Since the primary wiring A11 and the secondary wiring A12 of the first transformer Tr1 are closely coupled, the following equation (4) is satisfied.

[0168] [Mathematical Expression 4]

[0169] M 2 =L A11 ×L A12 (4)

[0170] Here, L A11 This represents the self-inductance of the primary wiring A11 when the secondary wiring A12 is open. Since the number of turns of the primary coil is the same as the number of turns of the secondary coil, equations (5) and (6) are satisfied.

[0171] [Mathematical Expression 5]

[0172] L A11 =L A12 (5)

[0173] [Mathematical Expression 6]

[0174] M = L A11 =L A12 (6)

[0175] Equation (3) is transformed into Equation (7).

[0176] [Mathematical Expression 7]

[0177] IA12 =jωL A12 / (jωL A12 +Z0)×I A11 (7)

[0178] With the primary wiring A11 open-circuited, the inductance L of the secondary wiring A12... A12 The resulting impedance jωL A12 The impedance Z0 is larger than the impedance Z0 connected across the secondary wiring A12, so that the impedance Z0 can be ignored. That is, jωL A12 The relationship >> Z0 holds. Therefore, I is derived from equation (7). A12 =I A11 .

[0179] However, the lower the measurement frequency, the lower the impedance jωL A12 The smaller, the better. Therefore, jωL A12 >>The relationship between Z0 and I does not hold, so the current I A12 With current I A11 This produces a difference.

[0180] Figure 21 This is a circuit diagram showing the state of connecting a precision low-resistance resistor across the two ends of secondary wiring A12. The resistance value R of the precision low-resistance resistor is R << ωL when the measurement frequency is at its lowest. A12 The relationship also holds true for that value.

[0181] With a precision low-resistance connection between the two ends of secondary wiring A12, the current I A11 and current I A12 The relationship between them satisfies the following equation (8).

[0182] [Mathematical Expression 8]

[0183] I A12 =jωL A12 / (jωL A12 +Z)×I A11 (8)

[0184] Here, impedance Z represents the value of the state after impedance Z0 and precision low resistance are connected in parallel. That is, the relationship of the following equation (9) holds.

[0185] [Mathematical Expression 9]

[0186] Z = R × Z0 / (R + Z0) (9)

[0187] R > Z always holds true, in ωL A12 >> In the case of R, ωL A12 >>Z is established.

[0188] Therefore, I is derived from equation (8). A12 =IA11 .

[0189] Accompanying the decrease in measurement frequency, the inductance L of secondary wiring A12... A12 and the inductor L of primary wiring A11 A11 When the value is reduced, the same current flows through both the primary wiring A11 and the secondary wiring A12 via the first resistor R1 and the second resistor R2 connected to the two ends of the primary wiring A11 and the secondary wiring A12, respectively. Therefore, the accuracy of the input capacitance measurement is improved.

[0190] The input capacitance measurement circuit 105 of embodiment 5 can achieve miniaturization of the first transformer Tr1 and improve the accuracy of the input capacitance even when the measurement frequency is low.

[0191] Figure 18 The first resistor R1 and the second resistor R2 shown can also be applied to the input capacitance measurement circuits 102 and 103 shown as Embodiment 2 and Embodiment 3 respectively, to achieve the same effect as described above.

[0192] The present invention allows for free combination of various embodiments, and appropriate modifications or omissions to each embodiment.

[0193] Explanation of the label

[0194] 20 LCR measuring instrument, 21 signal generator, 21A signal generator, 21B signal generator, 22 vector voltmeter, 23 current-voltage conversion circuit (IV conversion circuit), 101-105 input capacitance measurement circuit, A11 primary wiring, A12 secondary wiring, A21 primary wiring, A22 secondary wiring, C1-C7 capacitors, C13-C16 capacitors, G protection terminal, 11 power supply GND, 24 signal GND, Hc signal application terminal, Hp high-side potential measurement terminal, L1-L3 reactors, Lc current measurement terminal, Lp low-side potential measurement terminal, P1 terminal, Q1 area, Q2 area, R1 first resistor, R2 second resistor, Tr1 first transformer, Tr2 second transformer.

Claims

1. An input capacitance measuring circuit for measuring the input capacitance of a semiconductor device. in, The input capacitance measurement circuit has the following characteristics: A transformer consists of primary wiring and secondary wiring; Capacitor 1; Second capacitor; as well as Third capacitor One end of the primary wiring of the transformer is configured to be connected to the anode of the semiconductor device. The other end of the primary wiring of the transformer is connected to one end of the first capacitor. One end of the secondary wiring of the transformer is configured to be connected to the cathode of the semiconductor device. The other end of the secondary wiring of the transformer is connected to one end of the second capacitor. One end of the third capacitor is configured to be connected to the cathode of the semiconductor device. The other ends of the first capacitor, the second capacitor, and the third capacitor are electrically connected to each other.

2. The input capacitance measuring circuit according to claim 1, wherein, The number of turns of the primary coil in the primary wiring of the transformer is the same as the number of turns of the secondary coil in the secondary wiring of the transformer.

3. The input capacitance measuring circuit according to claim 1 or 2, wherein, The electrostatic capacitance of the first capacitor is the same as that of the second capacitor.

4. The input capacitance measuring circuit according to any one of claims 1 to 3, wherein, The anode and the cathode correspond to the collector electrode and the emitter electrode of the semiconductor device, respectively, or correspond to the drain electrode and the source electrode of the semiconductor device, respectively.

5. The input capacitance measuring circuit according to any one of claims 1 to 4, wherein, It also has: A first resistor connects one end and the other end of the primary wiring of the transformer; and The second resistor connects one end and the other end of the secondary wiring of the transformer. The resistance value of the first resistor is the same as the resistance value of the second resistor.

6. The input capacitance measuring circuit according to any one of claims 1 to 5, wherein, It also includes a transformer for generating current signals, comprising primary and secondary wiring. One end of the primary wiring of the transformer used for generating the current signal is configured to be connected to the gate electrode of the semiconductor device. One end of the secondary wiring of the transformer for generating the current signal is electrically connected to the other end of the first capacitor, the other end of the second capacitor, and the other end of the third capacitor.

7. A method for manufacturing a semiconductor device, wherein the input capacitance of the semiconductor device is measured using the input capacitance measuring circuit of claim 6, wherein... One end of the primary wiring of the transformer is connected to the anode of the semiconductor device. One end of the secondary wiring of the transformer and one end of the third capacitor are connected to the cathode of the semiconductor device. One end of the primary wiring of the transformer used to generate the current signal is connected to the gate electrode of the semiconductor device. One end of the secondary wiring of the transformer for generating the current signal is electrically connected to the other end of the first capacitor, the other end of the second capacitor, and the other end of the third capacitor. The other end of the primary wiring of the transformer used to generate the current signal is connected to the signal generator of the LCR measuring instrument. The gate electrode and the cathode of the semiconductor device are connected to the voltmeter of the LCR measuring instrument. The other end of the secondary wiring of the transformer used to generate the current signal is connected to the current-voltage conversion circuit of the LCR measuring instrument. Connect the other end of the first capacitor, the other end of the second capacitor, and the other end of the third capacitor to the ground of the LCR measuring instrument. A high-frequency signal is applied to the gate electrode of the semiconductor device from the signal generator of the LCR meter. The current flowing from the gate electrode through the anode and cathode of the semiconductor device into the input capacitance measuring circuit is measured as the current flowing from the ground through the current signal generating transformer into the current-voltage conversion circuit. The voltage between the gate electrode and the cathode of the semiconductor device is measured using the voltmeter. The input capacitance of the semiconductor device is measured based on the current and the voltage.

8. The method for manufacturing a semiconductor device according to claim 7, wherein, The signal application terminal of the signal generator is connected via the fourth capacitor to the other end of the primary wiring of the current signal generating transformer. The first potential measuring terminal of the voltmeter is connected to the gate electrode of the semiconductor device via the fifth capacitor. The second potential measuring terminal of the voltmeter is connected to the cathode of the semiconductor device via the sixth capacitor. The current measurement terminal of the current-voltage conversion circuit is connected to the other end of the secondary wiring of the current signal generation transformer via the 7th capacitor.

9. A method for manufacturing a semiconductor device, wherein the input capacitance of the semiconductor device is measured using the input capacitance measuring circuit according to any one of claims 1 to 5, wherein, One end of the primary wiring of the transformer is connected to the anode of the semiconductor device. One end of the secondary wiring of the transformer and one end of the third capacitor are connected to the cathode of the semiconductor device. The gate electrode of the semiconductor device is connected to the signal generator of the LCR measuring instrument. The gate electrode and the cathode of the semiconductor device are connected to the voltmeter of the LCR measuring instrument. The other end of the first capacitor, the other end of the second capacitor, and the other end of the third capacitor are connected to the current-voltage conversion circuit of the LCR measuring instrument. A high-frequency signal is applied to the gate electrode of the semiconductor device from the signal generator of the LCR meter. The current flowing from the gate electrode through the anode, cathode, and input capacitance measurement circuit of the semiconductor device into the current-to-voltage conversion circuit is measured. The voltage between the gate electrode and the cathode of the semiconductor device is measured using the voltmeter. The input capacitance of the semiconductor device is measured based on the current and the voltage.

10. The method of manufacturing a semiconductor device according to claim 9, wherein, The signal application terminal of the signal generator is connected to the gate electrode via the fourth capacitor. The first potential measuring terminal of the voltmeter is connected to the gate electrode via the fifth capacitor. The second potential measuring terminal of the voltmeter is connected to the cathode via the sixth capacitor.

11. A method for manufacturing a semiconductor device, wherein the input capacitance of the semiconductor device is measured using an input capacitance measuring circuit according to any one of claims 1 to 5, wherein, One end of the primary wiring of the transformer is connected to the anode of the semiconductor device. One end of the secondary wiring of the transformer and one end of the third capacitor are connected to the cathode of the semiconductor device. The anode of the semiconductor device is connected to the signal generator of the LCR measuring instrument. The gate electrode and the cathode of the semiconductor device are connected to the voltmeter of the LCR measuring instrument. The gate electrode of the semiconductor device is connected to the current-to-voltage conversion circuit of the LCR meter. Connect the other end of the first capacitor, the other end of the second capacitor, and the other end of the third capacitor to the ground of the LCR measuring instrument. A high-frequency signal is applied to the anode from the signal generator of the LCR meter. The current flowing from the anode through the cathode and the gate electrode of the semiconductor device into the current-to-voltage conversion circuit is measured. The voltage between the gate electrode and the cathode of the semiconductor device is measured using the voltmeter. The input capacitance of the semiconductor device is measured based on the current and the voltage.

12. The method of manufacturing a semiconductor device according to claim 11, wherein, The signal application terminal of the signal generator is connected to the anode via the fourth capacitor. The first potential measuring terminal of the voltmeter is connected to the gate electrode via the fifth capacitor. The second potential measuring terminal of the voltmeter is connected to the cathode via the sixth capacitor.

13. An input capacitance measuring circuit for measuring the input capacitance of a semiconductor device. in, The input capacitance measurement circuit has the following characteristics: The first transformer includes primary wiring and secondary wiring; The second transformer includes primary wiring and secondary wiring; The first capacitor; and Second capacitor, One end of the primary wiring of the first transformer is connected to one end of the primary wiring of the second transformer. One end of the secondary wiring of the first transformer is configured to be connected to the anode of the semiconductor device. The other end of the secondary wiring of the first transformer is connected to one end of the first capacitor. One end of the secondary wiring of the second transformer is configured to be connected to the cathode of the semiconductor device. The other end of the secondary wiring of the second transformer is connected to one end of the second capacitor. The other end of the primary wiring of the first transformer, the other end of the first capacitor, the other end of the primary wiring of the second transformer, and the other end of the second capacitor are electrically connected to each other.

14. The input capacitance measuring circuit according to claim 13, wherein, The number of turns of the primary coil in the primary wiring of the first transformer is the same as the number of turns of the primary coil in the primary wiring of the second transformer.

15. The input capacitance measuring circuit according to claim 14, wherein, The number of turns of the primary coil of the first transformer is the same as the number of turns of the secondary coil included in the secondary wiring of the first transformer. The number of turns of the primary coil of the second transformer is the same as the number of turns of the secondary coil included in the secondary wiring of the second transformer.

16. The input capacitance measuring circuit according to any one of claims 13 to 15, wherein, The electrostatic capacitance of the first capacitor is the same as that of the second capacitor.

17. The input capacitance measuring circuit according to any one of claims 13 to 16, wherein, The anode and the cathode correspond to the collector electrode and the emitter electrode of the semiconductor device, respectively, or correspond to the drain electrode and the source electrode of the semiconductor device, respectively.

18. A method for manufacturing a semiconductor device, wherein the input capacitance of the semiconductor device is measured using the input capacitance measuring circuit according to any one of claims 13 to 17, wherein, Connect one end of the secondary wiring of the first transformer to the anode of the semiconductor device. One end of the secondary wiring of the second transformer is connected to the cathode of the semiconductor device. Connect one end of the primary wiring of the first transformer and one end of the primary wiring of the second transformer to the signal generator of the LCR measuring instrument. The gate electrode and the anode of the semiconductor device are connected to the voltmeter of the LCR measuring instrument. The gate electrode of the semiconductor device is connected to the current-to-voltage conversion circuit of the LCR meter. Connect the other end of the primary wiring of the first transformer, the other end of the first capacitor, the other end of the primary wiring of the second transformer, and the other end of the second capacitor to the ground of the LCR measuring instrument. A high-frequency signal is applied from the signal generator of the LCR measuring instrument to one end of the primary wiring of the first transformer and one end of the primary wiring of the second transformer. The current flowing from the anode and cathode of the semiconductor device through the gate electrode into the current-to-voltage conversion circuit is measured. The voltage between the gate electrode and the anode of the semiconductor device is measured using the voltmeter. The input capacitance of the semiconductor device is measured based on the current and the voltage.

19. The method of manufacturing a semiconductor device according to claim 18, wherein, The signal application terminal of the signal generator is connected via the third capacitor to one end of the primary wiring of the first transformer and one end of the primary wiring of the second transformer. The first potential measuring terminal of the voltmeter is connected to the anode of the semiconductor device via a fourth capacitor. The second potential measuring terminal of the voltmeter is connected to the gate electrode of the semiconductor device via the fifth capacitor. The current measuring terminal of the current-to-voltage conversion circuit is connected to the gate electrode of the semiconductor device via a sixth capacitor. The protection terminal of the LCR measuring instrument connected to the ground is connected to the other end of the primary wiring of the first transformer, the other end of the first capacitor, the other end of the primary wiring of the second transformer, and the other end of the second capacitor.

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