CIRCUIT FOR PROTECTING DUT, METHOD FOR PROTECTING DUT, TESTING APPARATUS AND TESTING METHOD

Abstract

A circuit for protecting a DUT is disposed in parallel with a DUT which is supplied with current via wirings and switchable between conducting and non-conducting state. The circuit is switchable between conducting and non-conducing state and switched from non-conducting state to conducting state as the DUT is switched from conducting state to non-conducting state.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and features of the present invention will become apparent from the following description of embodiments, given in conjunction with the accompanying drawings, in which:

FIG. 1 shows a schematic configuration of an inspection device in accordance with an embodiment of the present invention;

FIG. 2 describes a circuit diagram illustrating a schematic configuration of a power device serving as a DUT;

FIG. 3 provides a circuit diagram depicting a test circuit, a probe card, signal lines and the power device of the inspection device of FIG. 1;

FIG. 4 illustrates a flowchart of a characteristic test process of the power device, as a testing method in accordance with an embodiment of the present invention;

FIGS. 5A and 5B describe a change in a current supply direction in accordance with a switching of ON/OFF state in each of IGBTs of the power device and a switching of ON/OFF state in an IGBT of a power device protection circuit, wherein FIG. 5A depicts a case where the respective IGBTs of the power device are in ON state whereas the IGBT of the power device protection circuit is in OFF state, and FIG. 5B shows a case where the respective IGBTs of the power device are in OFF state whereas the IGBT of the power device protection circuit is in ON state; and

FIGS. 6A and 6B present graphs illustrating an over-voltage application state to the power device in accordance with an existence of the power device protection circuit, wherein FIG. 6A shows a graph describing a case where the power device protection circuit does not exist, and FIG. 6B provides a graph depicting a case where the power device protection circuit exists.

Claims

1. A circuit for protecting a DUT, the circuit being disposed in parallel with a DUT which is supplied with current via wirings and switchable between conducting and non-conducting state, wherein the circuit is switchable between conducting and non-conducing state and switched from non-conducting state to conducting state as the DUT is switched from conducting state to non-conducting state.

2. The circuit of claim 1, wherein the circuit is switched from non-conducting state to conducting state before the DUT is switched from conducting state to non-conducting state.

3. The circuit of claim 2, wherein the circuit is switched from non-conducting state to conducting state after the DUT is switched to desired test state.

4. The circuit of claim 1, wherein the circuit and the DUT have insulated gate bipolar transistors.

5. A method for protecting a DUT which is supplied with current via wirings and switchable between conducting and non-conducting state, the method comprising the steps of: arranging a circuit for protecting a DUT in parallel with the DUT, the circuit being switchable between conducting and non-conducting state; andswitching the circuit from non-conducting state to conducting state as the DUT is switched from conducting state to non-conducting state.

6. The method of claim 5, wherein in the step of switching the circuit to conducting state, the circuit is switched from non-conducting state to conducting state before the DUT is switched from conducting state to non-conducting state.

7. The method of claim 6, wherein in the step of switching the circuit to conducting state, the circuit is switched from non-conducting state to conducting state after the DUT is switched to desired test state.

8. The method of claim 5, wherein the circuit and the DUT have insulated gate bipolar transistors.

9. A testing apparatus comprising: a power supply for supplying current;a wiring for connecting a DUT which is switchable between conducting and non-conducting state with the power supply; anda circuit for protecting the DUT, the circuit being disposed in parallel with the DUT and switchable between conducting and non-conducting state, wherein the circuit is switched from non-conducting state to conducting state as the DUT to which the current is supplied is switched from conducting state to non-conducting state.

10. A testing method using a testing apparatus including a power supply for supplying current and a wiring for connecting a DUT which is switchable between conducting and non-conducting state with the power supply, the method comprising the steps of: arranging a circuit for protecting a DUT in parallel with the DUT, the circuit being switchable between conducting and non-conducting state;performing a dynamic characteristic test, wherein the current is supplied to the DUT by switching the DUT to conducting state; andswitching the circuit from non-conducting state to conducting state as the DUT is switched from conducting state to non-conducting state.

11. The testing method of claim 10, further comprising a step of performing a static characteristic test of the DUT.

12. The testing method of claim 11, further comprising: performing a first static characteristic test of the DUT before performing the dynamic characteristic test; andperforming a second static characteristic test of the DUT after performing the dynamic characteristic test.