# US 12,761,265 B2 · Measurement method and measurement device

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- Number: US 12,761,265 B2
- Document ID: US12761265B2
- Status: Granted
- Kind: B2
- Application number: 18/237,292
- Filed: 2023-08-23
- Published: 2024-08-22
- Granted: 2026-10-13
- Earliest claimed: 2023-02-16
- Assignees: Kabushiki Kaisha Toshiba; Toshiba Electronic Devices & Storage Corporation
- Applicants: Kabushiki Kaisha Toshiba; Toshiba Electronic Devices & Storage Corporation
- Inventors: Takuma Hara; Tatsuya Ohguro; Shigeru Nakajima; Katsura Miyashita; Yasuhisa Oomuro
- Web page: https://patentgrep.com/patent/US12761265B2

## CPC

- G01R 31/2621: {for testing field effect transistors, i.e. FET's}
- G01R 31/26: Testing of individual semiconductor devices (testing of photovoltaic devices H02S50/10; testing or measuring during manufacture or treatment {H10P74/00})
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)

## Abstract

A measurement method includes determining a first relationship by measuring a reverse recovery charge of a semiconductor element at a plurality of conditions of a measurement device. The measurement device has mutually-different parasitic inductances at the plurality of conditions. The semiconductor element includes a diode component. The first relationship is between the parasitic inductance and a measured value of the reverse recovery charge. The method includes estimating a true value of the reverse recovery charge when the parasitic inductance is zero based on the first relationship.

## Claims

### Claim 1

A measurement method for measuring a reverse recovery charge of a semiconductor element including a diode component, comprising:
using a measurement device in which a direct-current power supply, a variable inductance, and a switching element are connected in series with a semiconductor element including a diode component, and, at a plurality of conditions in which a parasitic inductance of the measurement device is made mutually different by setting the variable inductance and a current change rate of a current flowing through the semiconductor element is set to an identical value by adjusting a value of a resistance connected to a control electrode of the switching element, acquiring, at each condition, a drain-source current waveform of the semiconductor element and calculating, as a reverse recovery charge, a time integral of a reverse recovery current over an entire duration of current oscillations;
based on the parasitic inductance and measured values of the reverse recovery charge, determining, at the identical current change rate, a first relationship between the parasitic inductance and the measured values of the reverse recovery charge;
determining a second relationship and a third relationship at the plurality of conditions of the measurement device having mutually-different parasitic inductances, the second relationship being between a current change rate and a charge transferred in an initial half period of a current oscillation, the third relationship being between the current change rate and a charge transferred in an entire duration of the current oscillation;
setting a saturated current change rate as the current change rate at an intersection of the second and third relationships in a graph illustrating a relationship between the current change rate and the charge;
determining a fourth relationship between the saturated current change rate and the parasitic inductance;
setting a saturated parasitic inductance by determining the parasitic inductance corresponding to an arbitrary value of the saturated current change rate based on the fourth relationship; and
setting a true value as the charge corresponding to the saturated parasitic inductance based on the first relationship.

### Claim 2 (depends on 1)

The method according to claim 1, further comprising:
determining the true value corresponding to an arbitrary value of the current change rate based on a fifth relationship between the saturated current change rate and the true value at the plurality of conditions of the measurement device having mutually-different parasitic inductances by plotting pairs of the saturated current change rate and the true value determined for the respective conditions.

### Claim 3 (depends on 1)

The method according to claim 1, wherein
the semiconductor element is a field-effect transistor, and
the method further comprises:
measuring an output charge amount of the semiconductor element; and
determining a difference by subtracting the measured output charge amount from the true value.

### Claim 4 (depends on 3)

The method according to claim 3, wherein
the output charge amount is estimated to be a charge contributing to a boost of a drain-source voltage of the semiconductor element, and
the difference is estimated to be a charge caused by recombination and discharge of carriers in the semiconductor element.

### Claim 5

A measurement method for measuring a reverse recovery charge of a semiconductor element including a diode component, comprising:
using a measurement device in which a direct-current power supply, a variable inductance, and a switching element are connected in series with a semiconductor element including a diode component, and, at a plurality of conditions in which a parasitic inductance of the measurement device is made mutually different by setting the variable inductance and a current change rate of a current flowing through the semiconductor element is set to an identical value by adjusting a value of a resistance connected to a control electrode of the switching element, acquiring, at each condition, a drain-source current waveform of the semiconductor element and calculating, as a reverse recovery charge, a time integral of a reverse recovery current over an entire duration of current oscillations;
based on the parasitic inductance and measured values of the reverse recovery charge, determining, at the identical current change rate, a first relationship between the parasitic inductance and the measured values of the reverse recovery charge;
determining a second relationship between a current change rate and a surge voltage at the plurality of conditions of the measurement device having mutually-different parasitic inductances;
setting a saturated current change rate as the current change rate corresponding to a reference potential in the second relationship, the reference potential being set between an anode potential and a cathode potential of a power supply;
determining a third relationship between the saturated current change rate and the parasitic inductance;
setting a saturated parasitic inductance by determining the parasitic inductance corresponding to an arbitrary value of the saturated current change rate based on the third relationship; and
setting the true value as the charge corresponding to the saturated parasitic inductance based on the first relationship.

### Claim 6 (depends on 5)

The method according to claim 5, further comprising:
determining the true value corresponding to an arbitrary value of the current change rate based on a fourth relationship between the saturated current change rate and the true value at the plurality of conditions of the measurement device having mutually-different parasitic inductances.

### Claim 7

A measurement method for measuring a reverse recovery charge of a semiconductor element including a diode component, comprising:
using a measurement device in which a direct-current power supply, a variable inductance, and a switching element are connected in series with a semiconductor element including a diode component, and, at a plurality of conditions in which a parasitic inductance of the measurement device is made mutually different by setting the variable inductance and a current change rate of a current flowing through the semiconductor element is set to an identical value by adjusting a value of a resistance connected to a control electrode of the switching element, acquiring, at each condition, a drain-source current waveform of the semiconductor element and calculating, as a reverse recovery charge, a time integral of a reverse recovery current over an entire duration of current oscillations;
based on the parasitic inductance and measured values of the reverse recovery charge, determining, at the identical current change rate, a first relationship between the parasitic inductance and the measured values of the reverse recovery charge;
determining a second relationship and a third relationship at the plurality of conditions of the measurement device having mutually-different parasitic inductances, the second relationship being between a current change rate and a charge transferred in an initial half period of a current oscillation, the third relationship being between the current change rate and a charge transferred in an entire duration of the current oscillation; and
setting a saturated current change rate as the current change rate at an intersection of the second and third relationships in a graph illustrating a relationship between the current change rate and the charge, and setting the true value as a charge at the intersection.

### Claim 8 (depends on 7)

The method according to claim 7, further comprising:
determining the true value corresponding to an arbitrary value of the current change rate based on a fourth relationship between the saturated current change rate and the true value at the plurality of conditions of the measurement device having mutually-different parasitic inductances.