Testing device, testing method, and method for manufacturing semiconductor device

Abstract

A testing device (100) comprises: a current measurement unit (30) that measures the current value of the current flowing through a subject (10) which includes a semiconductor element; a destruction detection unit (50) that detects destruction of the subject (10); a semiconductor switch (64) that is connected between a power source unit (20) and the subject (10) and that blocks the current flowing through the subject (10) when the destruction of the subject (10) has been detected; and a load (70) that is connected between the semiconductor switch (64) and the subject (10). The destruction detection unit (50) determines that the subject (10) has been destroyed when the current value is equal to or greater than a first current threshold value at a first timing which is when the differential value of the current value becomes equal to or greater than a first reference value from being less than the first reference value.

Description

Testing device, testing method, and semiconductor device manufacturing method

[0001] The present disclosure relates to a test device, a test method, and a method for manufacturing a semiconductor device.

[0002] Conventionally, power semiconductors are subjected to electrical characteristic tests to check their quality and performance before shipping. Defective power semiconductors can be destroyed during the electrical characteristic tests. When a power semiconductor is destroyed, a large breakdown current flows, damaging components used in the test (e.g., circuits, jigs, etc.). To protect these components, a circuit breaker is used.

[0003] Japanese Patent Laid-Open Publication No. 2016-8936 (Patent Document 1) discloses a semiconductor device inspection circuit that includes a semiconductor device to be inspected, a protection element connected in series to the semiconductor device, a switching element connected in series to the semiconductor device and the protection element, and a coil that forms a loop path together with the semiconductor device and the protection element when the switching element is turned off.

[0004] Japanese Patent Application Laid-Open No. 2016-8936

[0005] In Patent Document 1, a characteristic test of an object to be tested is performed by controlling the on / off of a switching element to change the current and voltage flowing through the object to be tested (for example, a diode, which is a semiconductor element). In the characteristic test, if the object to be tested is broken down, the breakage of the object to be tested is detected if the current flowing after the breakage exceeds a threshold current.

[0006] When breakdown of the test object is detected, the breakdown current flowing due to the breakdown is interrupted using an interrupting circuit (e.g., a switching element). The shorter the time from when the test object is broken to when the breakdown current is interrupted, the smaller the damage to the test components and the like will be, so it is necessary to interrupt the breakdown current quickly.

[0007] In Patent Document 1, after the test object is broken, the breakdown of the test object is detected when the breakdown current becomes equal to or greater than a threshold current. Therefore, it takes time from when the test object is actually broken to when the breakdown is detected, and as a result, it takes a long time to shut off the breakdown current, which increases the damage to the test components and the like.

[0008] An object of one aspect of the present disclosure is to provide a technology that can quickly detect breakdown of a test object during testing and cut off the breakdown current more quickly, thereby reducing damage to components used in the test.

[0009] A test apparatus according to an embodiment includes a current measurement unit that measures a current value of a current flowing through a test object including a semiconductor device, a breakdown detection unit that detects breakdown of the test object, a semiconductor switch connected between a power supply unit and the test object and that cuts off the current flowing through the test object when breakdown of the test object is detected, and a load connected between the semiconductor switch and the test object. The breakdown detection unit determines that the test object has been broken if the current value is equal to or greater than a first current threshold at a first timing when a differential value of the current value changes from less than a first reference value to equal to or greater than the first reference value.

[0010] A test apparatus according to another embodiment includes a current measurement unit that measures a current value of a current flowing through a test object including a semiconductor device, a voltage measurement unit that measures a voltage value of a voltage applied to the test object, a breakdown detection unit that detects breakdown of the test object, a semiconductor switch connected between a power supply unit and the test object and that cuts off the current flowing through the test object when breakdown of the test object is detected, and a load connected between the semiconductor switch and the test object. The breakdown detection unit determines that the test object has been broken if the current value is equal to or greater than a first current threshold at a second timing when the differential value of the voltage value changes from equal to or greater than a second reference value to less than the second reference value.

[0011] According to yet another embodiment, there is provided a testing method using a testing apparatus. The testing apparatus includes a semiconductor switch connected between a power supply unit and a test object including a semiconductor device, the semiconductor switch cutting off current flowing through the test object when breakdown of the test object is detected, and a load connected between the semiconductor switch and the test object. The testing method includes measuring a current value of a current flowing through the test object including the semiconductor device, and detecting breakdown of the test object. The detecting step includes determining that the test object has been broken if the current value is equal to or greater than a first current threshold at a first timing when a differential value of the current value changes from less than a first reference value to equal to or greater than the first reference value.

[0012] According to yet another embodiment, there is provided a testing method using a testing apparatus. The testing apparatus includes a semiconductor switch connected between a power supply unit and a test object including a semiconductor device, the semiconductor switch cutting off a current flowing through the test object when breakdown of the test object is detected, and a load connected between the semiconductor switch and the test object. The testing method includes the steps of measuring a current value of a current flowing through the test object including the semiconductor device, measuring a voltage value of a voltage applied to the test object, and detecting breakdown of the test object. The detecting step includes the step of determining that the test object has been broken if the current value is equal to or greater than a first current threshold at a second timing when a differential value of the voltage value changes from equal to or greater than a second reference value to less than the second reference value.

[0013] According to yet another embodiment, there is provided a method for manufacturing a semiconductor device, the method including the steps of preparing a semiconductor element, evaluating characteristics of the semiconductor element using the above-described test apparatus, and commercializing a semiconductor device including the evaluated semiconductor element.

[0014] According to the present disclosure, damage to components used in testing can be reduced by quickly detecting breakdown of the test object during testing and cutting off the breakdown current more quickly.

[0015] FIG. 7 is a diagram showing an example of the overall configuration of a test apparatus. FIG. 8 is a diagram showing an example of the overall configuration of a test apparatus according to a first embodiment. FIG. 9 is a timing chart for explaining an example of a processing procedure of the test apparatus according to the first embodiment. FIG. 10 is a timing chart for explaining another example of a processing procedure of the test apparatus according to the first embodiment. FIG. 11 is an enlarged view of a part of the timing chart of FIG. 4. FIG. 12 is a timing chart for explaining an example of a processing procedure of the test apparatus according to the second embodiment. FIG. 13 is a timing chart for explaining another example of a processing procedure of the test apparatus according to the second embodiment. FIG. 14 is an enlarged view of a part of the timing chart of FIG. 7. FIG. 15 is a block diagram showing an example of the functional configuration of a destruction detection unit. FIG. 16 is a timing chart for explaining an example of a processing procedure of the test apparatus according to the third embodiment. FIG. 17 is a flowchart showing a method for manufacturing a semiconductor device according to a fourth embodiment.

[0016] Hereinafter, the present embodiment will be described with reference to the drawings. In the following description, the same components are denoted by the same reference numerals. The names and functions of these components are also the same. Therefore, detailed description thereof will not be repeated.

[0017] Embodiment 1. <Overall Configuration> Fig. 1 is a diagram showing an example of the overall configuration of a test apparatus 100. Referring to Fig. 1, the test apparatus 100 is an apparatus for performing an electrical characteristic test on a test object 10, which is a semiconductor device. The electrical characteristic test is an inductive load switching test, a RBSOA (Reverse Biased Safe Operating Area) test, or the like. The test apparatus 100 is configured to detect breakdown during a turn-off operation of the test object 10 in the electrical characteristic test on the test object 10.

[0018] Specifically, the test apparatus 100 includes a test object 10, a power supply unit 20, a current measurement unit 30, a Vce voltage measurement unit 40, a Vge voltage measurement unit 41, a breakdown detection unit 50, a current interruption unit 60, a load 70, a regenerative diode 82, a diode 84, and a gate driver 90. The breakdown detection unit 50 may be configured, for example, by a dedicated circuit, or part or all of it may be configured by an FPGA (Field Programmable Gate Array) or the like.

[0019] The test object 10 is, for example, a semiconductor element such as an IGBT (Insulator Gate Bipolar Transistor) or a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor). Note that the test object 10 may also be a semiconductor chip, a semiconductor wafer, a semiconductor module, a semiconductor package, or the like that includes a semiconductor element.

[0020] The power supply unit 20 is a power supply used in the electrical characteristic test. Specifically, the power supply unit 20 includes a power supply 22 and a capacitor 24. The power supply 22 supplies a DC power supply voltage for the electrical characteristic test (hereinafter also referred to as "test voltage Vcc"). The capacitor 24 is used as a current source for the current in the electrical characteristic test.

[0021] The current measuring unit 30 measures the current value Icv of the current Ic flowing through the test subject 10. The Vce voltage measuring unit 40 measures the voltage value Vcev of the voltage Vce applied between the collector and emitter of the test subject 10. The Vge voltage measuring unit 41 measures the voltage value Vge applied between the gate and emitter of the test subject 10.

[0022] The breakdown detection unit 50 has a function of detecting breakdown of the test object 10. The breakdown detection unit 50 receives input of the current value Icv of the current Ic measured by the current measurement unit 30 and the voltage value Vcev of the voltage Vce measured by the Vce voltage measurement unit 40. The breakdown detection unit 50 according to the first embodiment detects breakdown of the test object 10 based on the current value Icv and the current differential value Icdi, which is the time differential value of the current value Icv. When the breakdown detection unit 50 detects breakdown of the test object 10, it outputs an interruption signal to the current interruption unit 60 to interrupt the current flowing due to the breakdown. Details of the breakdown detection method for the test object 10 will be described later.

[0023] The current interruption unit 60 interrupts the current flowing through the test subject 10. Specifically, the current interruption unit 60 includes a gate driver 62 and a semiconductor switch 64, which is an interruption switch. The gate driver 62 controls the gate voltage supplied to the semiconductor switch 64 to turn the semiconductor switch 64 on or off. Typically, the gate driver 62 turns the semiconductor switch 64 on at the start of a test, and turns the semiconductor switch 64 off when a breakdown detection signal is received from the breakdown detection unit 50 (i.e., when breakdown in the test subject 10 is detected) and when the test is completed.

[0024] The semiconductor switch 64 is connected between the power supply unit 20 and the test object 10, and cuts off the current flowing through the test object 10 when breakdown of the test object 10 is detected. Specifically, the semiconductor switch 64 is turned off by the gate driver 62 immediately after breakdown of the test object 10 is detected, and cuts off the path of the current flowing through the test object 10. The semiconductor switch 64 is a semiconductor element such as an IGBT or MOSFET, as it must operate at high speed.

[0025] The load 70 is connected between the semiconductor switch 64 and the test object 10, and is used as an inductive load for electrical characteristic tests (for example, inductive load switching tests, RBSOA tests).

[0026] The regenerative diode 82 is connected in parallel to the load 70. The regenerative diode 82 functions as a bypass for the current flowing through the load 70 when the semiconductor switch 64 or the test object 10 is in the off state, and prevents a back electromotive force from being generated by the current flowing through the load 70.

[0027] The diode 84 is a flywheeling diode connected in anti-parallel (that is, in parallel and in a reverse bias direction) to the subject 10 as a semiconductor element.

[0028] The gate driver 90 functions as a switching control unit that controls the switching operation (i.e., on / off operation) of the test subject 10. Specifically, the gate driver 90 inputs a rectangular wave switching pulse to the gate electrode of the test subject 10, and performs the switching operation (i.e., on / off operation) of the test subject 10, thereby performing an electrical characteristic test.

[0029] The circuit of the test apparatus 100 shown in Figure 1 is an example, and any circuit capable of implementing a switching test using an inductive load may be used. Other protection mechanisms, circuits for increasing speed, etc. may also be added to the circuit shown in Figure 1. Furthermore, the relative positions of the components are not limited to those shown in Figure 1. However, in order to measure current and voltage more accurately, it is desirable that the current measuring unit 30 be provided in close proximity to the test object 10 and that the Vce voltage measuring unit 40 be directly probed to the test object 10.

[0030] Fig. 2 is a diagram showing an example of the overall configuration of test apparatus 100 according to embodiment 1. Specifically, Fig. 2 shows an example of the overall configuration of test apparatus 100 configured with the minimum necessary components in embodiment 1.

[0031] 2 differs from the test apparatus 100 of Fig. 1 in that it does not have a Vce voltage measuring unit 40. This means that in the first embodiment, the Vce voltage measuring unit 40 is not necessary to realize the operation of detecting breakdown of the test object 10, but does not mean that Vce voltage measurement becomes unnecessary in the inductive load switching test or the RBSOA test.

[0032] The processing procedure of the test apparatus 100 according to the first embodiment will be described below. Note that, although the timing charts in Figures 3, 4, and 5 described below also show the voltage value Vcev of the voltage Vce, this is shown for reference in order to explain the mechanism by which the test subject 10 is destroyed in the electrical characteristics test, and the voltage value Vcev of the voltage Vce does not contribute to the detection of destruction of the test subject 10 shown in the first embodiment.

[0033] <Processing Procedure> The processing procedure of the test apparatus 100 in the electrical characteristic test will be described in the cases where the test subject 10 is not destroyed and where the test subject 10 is destroyed.

[0034] 3 is a timing chart for explaining an example of a processing procedure of test apparatus 100 according to embodiment 1. Specifically, FIG. 3 shows a processing procedure of test apparatus 100 in the case where test subject 10 is not destroyed in an electrical characteristic test.

[0035] As shown in Fig. 3, a positive current threshold L1 and a current threshold L2 greater than the current threshold L1 are defined for the current Ic. The current threshold L1 is used to detect breakdown of the test object 10 when the test object 10 is switched from an ON state to an OFF state during testing. Specifically, the current threshold L1 is a threshold for distinguishing whether the slowing of the decrease in the current Ic is due to breakdown of the test object 10 during a switching operation or due to the test object 10 not being broken and the switching operation having been completed normally. The current threshold L2 indicates a test current value that serves as a trigger for switching the test object 10 from an ON state to an OFF state during an electrical characteristic test.

[0036] A negative reference value K1 is set for the current differential value Icdi. The reference value K1 is a value for detecting a decrease (i.e., a slowdown) in the rate of decrease of the current Ic when the test object 10 is controlled from an ON state to an OFF state, thereby decreasing the current Ic flowing through the test object 10. The current threshold value L1 and the reference value K1 are used to determine whether or not the test object 10 is broken.

[0037] The gate driver 90 controls the test subject 10 to the ON state, thereby increasing the current value Icv of the current Ic flowing through the test subject 10, and controls the test subject 10 to the OFF state when the current value Icv becomes equal to or greater than the current threshold L2.

[0038] The breakdown detection unit 50 receives an input of a current value Icv of the current Ic. The breakdown detection unit 50 calculates a current differential value Icdi of the current value Icv. The breakdown detection unit 50 determines whether or not the test subject 10 has broken down based on the current value Icv and the current differential value Icdi. Typically, the breakdown detection unit 50 performs a detection operation for breakdown of the test subject 10 during a period from the time when the current value Icv becomes equal to or greater than a current threshold L2 until a specified time (for example, a differential detection time, which will be described later) has elapsed.

[0039] The flow of the electrical characteristic test will be explained below. At the start of the test, the semiconductor switch 64 is turned on by the gate driver 62. The power supply 22 outputs a test voltage Vcc, and an electric charge is charged in the capacitor 24. At this time, a voltage Vce is applied between the collector and emitter of the test subject 10. Next, the gate driver 90 applies a voltage Vge to the test subject 10 to turn it on, causing a current to flow from the capacitor 24 through the semiconductor switch 64 and the load 70 to the test subject 10.

[0040] The current Ic flowing through the test object 10 gradually increases, and at timing (e.g., time) t1, when the current value Icv becomes equal to or greater than a current threshold L1, a current level determination signal for determining the magnitude of the current value Icv becomes active (e.g., high level). The current level determination signal is active when the current value Icv is equal to or greater than the current threshold L1, and is inactive (e.g., low level) when the current value Icv is less than the current threshold L1. The current level determination signal is monitored by the breakdown detection unit 50.

[0041] Furthermore, when the current Ic increases and the current value Icv reaches the current threshold L2 (i.e., the specified test current value) at timing t2, the gate driver 90 switches the test object 10 to the OFF state. At this time, the differential detection enable signal becomes enabled (e.g., high level). The differential detection enable signal becomes enabled at the timing when the current value Icv reaches the current threshold L2, and becomes disabled (e.g., low level) after a specified time T1 has elapsed from that timing. Hereinafter, the specified time T1 will also be referred to as the "differential detection time T1."

[0042] As the test object 10 enters the OFF state, the current Ic begins to decrease. As the current Ic decreases, the current differential value Icdi becomes less than the reference value K1 at timing t3. As the current differential value Icdi becomes less than the reference value K1, the Ic decrease rate determination signal becomes valid (for example, high level). The Ic decrease rate determination signal is valid when the current differential value Icdi is less than the reference value K1, and is invalid when the current differential value Icdi is equal to or greater than the reference value K1.

[0043] Furthermore, the current Ic continues to decrease, and at timing t4, when the current value Icv becomes less than the current threshold L1, the current level determination signal becomes invalid.

[0044] When the decrease rate of the current Ic decreases and the current differential value Icdi becomes equal to or greater than the reference value K1 at time t5, the Ic decrease rate determination signal becomes invalid. At this time, the current level determination signal is in an invalid state (i.e., the current value Icv is less than the current threshold L1), so the breakdown detection unit 50 does not detect breakdown of the test object 10. Therefore, the interruption signal remains in an invalid state. Therefore, the breakdown detection unit 50 may determine that the test object 10 is not broken if the current value Icv is less than the current threshold L1 at time t5 when the current differential value Icdi becomes equal to or greater than the reference value K1.

[0045] Thereafter, when the current value Icv becomes 0 A and the differential detection time T1 has elapsed since the test subject 10 started its off operation, the differential detection enable signal becomes invalid, and the electrical characteristic test ends. This also ends the operation of the breakdown detection unit 50 to detect breakdown of the test subject 10.

[0046] In the example of FIG. 3 , the semiconductor switch 64 is turned on from the start of the test, but it is sufficient that the semiconductor switch 64 is turned on by the time the test subject 10 is turned on. Therefore, the semiconductor switch 64 may be turned off at the start of the test. The power supply 22 applies a voltage near 0 V to the test subject 10 from the start of the test, but this is not limited to this. For example, the power supply 22 may be outputting a test voltage at the start of the test, assuming that tests are performed continuously. Alternatively, the power supply 22 may output a voltage higher than the test voltage at the start of the test, and then reduce the voltage to the test voltage before the test subject 10 is turned on. In other words, it is sufficient that the power supply 22 is configured so that the test voltage is applied to the test subject 10 by the time the test subject 10 is turned on.

[0047] 3, the configuration in which the test object 10 is turned off when the current value Icv of the current Ic becomes equal to or greater than the current threshold L2 is described as a trigger, but the present invention is not limited to this configuration. For example, a method may be used in which a timer is set to apply a voltage to the load 70 for the current value Icv to become equal to the current threshold L2. As an example, a method may be used in which a timer is set to apply a voltage calculated from the inductance value of the load 70 and the test voltage from the power supply 22. As another example, a fine-tuned voltage application time may be set by operating the test circuit shown in FIG. 1 and checking the waveform of the actual current Ic. Furthermore, a method may be used in which a timer is set to apply a voltage calculated based on the waveform of the current Ic obtained by simulation.

[0048] Fig. 4 is a timing chart for explaining another example of the processing procedure of test apparatus 100 according to the first embodiment. Fig. 5 is an enlarged view of a part of the timing chart of Fig. 4. Specifically, Figs. 4 and 5 show timing charts in the case where test object 10 is destroyed in an electrical characteristic test.

[0049] 4 and 5, the flow up to timing t3 is the same as the flow in FIG. 3. Referring to FIG. 5, after timing t3, while the current Ic is decreasing, the test object 10 is destroyed. When the test object 10 is destroyed, the rate of decrease of the current Ic slows down, the current Ic starts to increase, and the current differential value Icdi increases. At timing t6 immediately after the test object 10 is destroyed, when the current differential value Icdi becomes equal to or greater than the reference value K1, the Ic decrease rate determination signal becomes invalid. At this time, the current value Icv of the current Ic is equal to or greater than the current threshold value L1, so the current level determination signal remains valid.

[0050] In this way, the destruction detection unit 50 determines that the test object 10 has been destroyed if the current value Icv is equal to or greater than the current threshold L1 at the first timing (i.e., timing t6) when the current differential value Icdi changes from less than the first reference value (i.e., reference value K1) to equal to or greater than the reference value K1. On the other hand, as shown in the timing chart of Fig. 3, if the test object 10 is not destroyed, it is understood that the current value Icv is less than the current threshold L1 at the timing (i.e., timing t5) when the current differential value Icdi becomes equal to or greater than the reference value K1.

[0051] 5 , when the destruction detection unit 50 determines that the test object 10 has been destroyed, the shutdown signal is enabled. The shutdown signal is latched (i.e., maintained) in the enabled state. At this time, the destruction detection unit 50 outputs the shutdown signal to the gate driver 62.

[0052] Upon receiving the shut-off signal, the gate driver 62 turns off the semiconductor switch 64. As the semiconductor switch 64 turns off, the current value Icv decreases, and at timing t7, the current value Icv becomes less than the current threshold L1, and the current level determination signal becomes invalid.

[0053] Thereafter, when the current value Icv becomes 0 A and the differential detection time T1 has elapsed since the test object 10 started its off operation, the differential detection valid signal becomes invalid and the electrical characteristic test ends.

[0054] After the breakdown of the test object 10 is detected, until the differential detection enable signal is disabled, the current Ic takes on an unpredictable waveform due to the effects of the breakdown of the test object 10 and the off operation of the semiconductor switch 64. As a result, the current differential value Icdi and the Ic decrease rate determination signal become unstable, and the cutoff signal is maintained in an enabled state from timing t6 onwards.

[0055] Next, the difference between the method of detecting damage to the specimen 10 by the damage detection unit 50 and the method of detecting damage according to a comparative example will be described with reference to FIG.

[0056] As described above, the test object 10 is broken while the current Ic is decreasing with the test object 10 in the off state. The breakdown detection unit 50 according to the first embodiment detects breakdown of the test object 10 based on the fact that the current value Icv is equal to or greater than the current threshold L1 at the timing when the current differential value Icdi becomes equal to or greater than the reference value K1 (i.e., timing t6). Specifically, when the test object 10 is broken, the rate of decrease of the current value Icv decreases, and thereafter, the current value Icv increases. The breakdown detection unit 50 detects, using the current differential value Icdi, that the decrease of the current value Icv becomes gradual immediately after the test object 10 is broken, and determines that the test object 10 is broken on the condition that the current value Icv at the time of detection is equal to or greater than the current threshold L1.

[0057] On the other hand, in the breakdown detection method according to the comparative example, breakdown of the test specimen 10 is detected by focusing on the increase in the current value Icv after breakdown of the test specimen 10. Specifically, breakdown of the test specimen 10 is detected on the condition that the current value Icv gradually increases and becomes equal to or greater than the current threshold Lx at timing tx, where the current threshold Lx is greater than the current threshold L2. It can be seen that, according to the breakdown detection method according to the comparative example, breakdown of the test specimen 10 cannot be detected until the current Ic increases to a certain value or more after breakdown of the test specimen 10.

[0058] According to the breakdown detection method of the first embodiment, by detecting a decrease in the rate of decrease of the current value Icv using the current differential value Icdi, breakdown of the test object 10 can be detected at timing t6 before the current value Icv starts to increase. Therefore, compared to the breakdown detection method of the comparative example, the breakdown detection method of the first embodiment can detect breakdown of the test object 10 faster (for example, by detecting it earlier by the time equivalent to "tx-t6") and can shut off the breakdown current earlier. This reduces damage to components used in the test and improves the reliability of the test apparatus 100. Furthermore, it is possible to reduce the repair and replacement costs of damaged components.

[0059] Embodiment 2. The processing procedure of the test apparatus 100 according to embodiment 2 will be described in the cases where the test subject 10 is not broken and where the test subject 10 is broken in an electrical characteristic test. In embodiment 1, a configuration was described in which breakdown of the test subject 10 is detected using the current value Icv and current differential value Icdi of the current Ic. In embodiment 2, however, a configuration will be described in which breakdown of the test subject 10 is detected using the current value Icv and voltage differential value Vcedi, which is the time differential value of the voltage value Vcev. Note that an example of the overall configuration of the test apparatus 100 configured with the minimum necessary components in embodiment 2 is shown in FIG. 1 above.

[0060] 6 is a timing chart for explaining an example of a processing procedure of the test apparatus 100 according to the second embodiment. Specifically, FIG. 6 shows a processing procedure of the test apparatus 100 in the case where the test object 10 is not destroyed in the electrical characteristics test.

[0061] 6, a current threshold L1 and a current threshold L2 are defined for the current Ic, as in FIG. 3. A negative reference value K2 is defined for the voltage differential value Vcedi. The reference value K2 is a value for detecting a decrease in the voltage Vce applied to the test object 10. The current threshold L1 and the reference value K2 are used to determine whether or not the test object 10 is broken.

[0062] The breakdown detection unit 50 receives input of the current value Icv of the current Ic and the voltage value Vcev of the voltage Vce. The breakdown detection unit 50 calculates a voltage differential value Vcedi of the voltage value Vcev. The breakdown detection unit 50 determines whether or not the test object 10 has broken down based on the current value Icv and the voltage differential value Vcedi.

[0063] The flow of the electrical characteristics test will be explained below. At the start of the test, the semiconductor switch 64 is turned on by the gate driver 62. The power supply 22 outputs the test voltage Vcc, and the capacitor 24 is charged. At this time, the voltage Vce is applied between the collector and emitter of the test object 10. As the voltage value Vcev of the voltage Vce increases, the voltage differential value Vcedi increases.

[0064] At timing t10, the gate driver 90 applies a voltage Vge to the test object 10 to turn it on, causing a current to flow from the capacitor 24 through the semiconductor switch 64 and the load 70 to the test object 10. As a result, the voltage value Vcev decreases, causing the voltage differential value Vcedi to become negative, and the Vce decrease rate determination signal becomes valid. At this time, the current value Icv of the current Ic is less than the current threshold value L1, so the current level determination signal is invalid. Therefore, no breakdown of the test object 10 is detected, and the shut-off signal remains invalid.

[0065] When the voltage value Vcev drops to the on-voltage level, the voltage Vce stops fluctuating and the voltage differential value Vcedi returns to a level near 0. At this time, the voltage differential value Vcedi becomes equal to or greater than the reference value K2, so the Vce decrease rate determination signal becomes invalid.

[0066] Subsequently, the current Ic flowing through the test object 10 gradually increases, and at timing t11, when the current value Icv reaches or exceeds the current threshold L1, the current level determination signal becomes valid. The current Ic further increases, and at timing t12, when the current value Icv reaches the current threshold L2, the gate driver 90 turns off the test object 10. At this time, the differential detection enable signal becomes valid.

[0067] As the test object 10 enters the OFF state, the voltage Vce begins to increase. As the voltage Vce increases, the voltage differential value Vcedi also increases at timing t12.

[0068] Furthermore, when the voltage Vce increases to the test voltage value, the current Ic decreases, and at timing t13, the voltage differential value Vcedi returns to near 0 V. After that, at timing t14, when the current value Icv of the decreasing current Ic becomes less than the current threshold value L1, the current level determination signal becomes invalid.

[0069] Thereafter, when the current value Icv becomes 0 A and the differential detection time T1 has elapsed since the test object 10 started its off operation, the differential detection valid signal becomes invalid and the electrical characteristic test ends.

[0070] Fig. 7 is a timing chart for explaining another example of the processing procedure of the test apparatus 100 according to the second embodiment. Fig. 8 is an enlarged view of a part of the timing chart of Fig. 7. Specifically, Figs. 7 and 8 show timing charts in the case where the test object 10 is destroyed in an electrical characteristic test.

[0071] 7 and 8, the flow up to timing t13 is the same as the flow in Fig. 6. Referring to Fig. 8, after timing t13, while the current Ic is decreasing, the test object 10 is destroyed.

[0072] When the test object 10 is broken down, the voltage Vce starts to decrease, and the voltage differential value Vcedi also decreases. At timing t16 immediately after the test object 10 is broken down, when the voltage differential value Vcedi becomes less than the reference value K2, the Vce decrease rate determination signal becomes valid. At this time, the current value Icv of the current Ic is equal to or greater than the current threshold value L1, so the current level determination signal is valid.

[0073] In this way, the breakdown detection unit 50 determines that the test subject 10 has been broken down if the current value Icv is equal to or greater than the current threshold L1 at the timing when the voltage differential value Vcedi changes from equal to or greater than the reference value K2 to less than the reference value K2 (i.e., at timing t16). In this regard, if the test subject 10 is not broken down, the voltage differential value Vcedi does not become less than the reference value K2 after the test subject 10 starts its off operation, as shown in the timing chart of FIG.

[0074] 8 , when the destruction detection unit 50 determines that the test object 10 has been destroyed, the shutdown signal is enabled. The shutdown signal is maintained in the enabled state. At this time, the destruction detection unit 50 outputs the shutdown signal to the gate driver 62.

[0075] Upon receiving the shut-off signal, the gate driver 62 turns off the semiconductor switch 64. As the semiconductor switch 64 turns off, the current value Icv decreases, and at timing t17, the current value Icv becomes less than the current threshold L1, and the current level determination signal becomes invalid.

[0076] Thereafter, when the current value Icv becomes 0 A and the differential detection time T1 has elapsed since the test object 10 started its off operation, the differential detection valid signal becomes invalid and the electrical characteristic test ends.

[0077] After the breakdown of the test object 10 is determined, until the differential detection enable signal is disabled, the voltage Vce takes on an unpredictable waveform due to the effects of the breakdown of the test object 10 and the turn-off operation of the semiconductor switch 64. As a result, the voltage differential value Vcedi and the Vce decrease rate determination signal become indefinite, and the cutoff signal is maintained in an enabled state from timing t16 onwards.

[0078] Next, the difference between the method of detecting damage to the specimen 10 by the damage detection section 50 according to the second embodiment and the method of detecting damage according to the comparative example will be described with reference to FIG.

[0079] As described above, the test subject 10 is broken while the current Ic is decreasing with the test subject 10 in the off state. The breakdown detection unit 50 according to the second embodiment detects breakdown of the test subject 10 based on the current value Icv being equal to or greater than the current threshold L1 at the second timing (i.e., timing t16) when the voltage differential value Vcedi becomes less than the second reference value (i.e., reference value K2). Specifically, when the test subject 10 is broken, the rate of increase of the voltage value Vcev decreases, and the voltage Vce begins to decrease. The breakdown detection unit 50 detects, using the voltage differential value Vcedi, that the voltage value Vcev has begun to decrease immediately after the test subject 10 is broken, and determines that the test subject 10 has been broken, provided that the current value Icv at the time of detection is equal to or greater than the current threshold L1.

[0080] 5, breakdown of the test specimen 10 is detected on the condition that the current value Icv becomes equal to or greater than the current threshold Lx at timing tx. Therefore, breakdown of the test specimen 10 cannot be detected until the current Ic increases to a certain value or more after breakdown of the test specimen 10.

[0081] According to the breakdown detection method of the second embodiment, breakdown of the test object 10 can be detected using the voltage differential value Vcedi at timing t16 when the voltage value Vcev starts to decrease after breakdown of the test object 10. Therefore, compared to the breakdown detection method of the comparative example, the breakdown detection method of the second embodiment can detect breakdown of the test object 10 faster (for example, detect it earlier by the time equivalent to "tx-t16") and can shut off the breakdown current earlier. This reduces damage to components used in the test and improves the reliability of the test equipment using the interrupter circuit. Furthermore, it is possible to reduce the repair and replacement costs of damaged components.

[0082] Third Embodiment In the third embodiment, the function of the destruction detection unit 50 will be specifically described. Fig. 9 is a block diagram showing an example of the functional configuration of the destruction detection unit 50. Referring to Fig. 9, the destruction detection unit 50 includes a control unit 501, a first current threshold setting unit 503, a second current threshold setting unit 505, a reference value setting unit 507, a first current comparison unit 509, a second current comparison unit 511, a differential calculation unit 513, a differential value comparison unit 515, and a determination unit 517. These functional configurations are realized by, for example, a dedicated circuit, an FPGA, or the like.

[0083] The control unit 501 receives a second current level judgment signal from the second current comparison unit 511, or receives a turn-off signal (hereinafter also simply referred to as an "off signal") for controlling the test subject 10 to an off state from the gate driver 90. The control unit 501 has an internal timer function. In order to detect breakdown during the turn-off operation of the test subject 10, the control unit 501 transmits a timing signal to the judgment unit 517 at a timing when a predetermined time has elapsed since the timing of receiving the second current level judgment signal or the off signal. In this way, the control unit 501 instructs the judgment unit 517 on the timing to perform breakdown judgment.

[0084] Furthermore, the control unit 501 transmits a first command signal to the first current threshold setting unit 503, a second command signal to the second current threshold setting unit 505, and a third command signal to the reference value setting unit 507. The first command signal is a signal for instructing the first current threshold setting unit 503 to generate a current threshold L1. The second command signal is a signal for instructing the second current threshold setting unit 505 to generate a current threshold L2. The third command signal is a signal for instructing the reference value setting unit 507 to generate a reference value K1.

[0085] The first current threshold setting unit 503 generates a current threshold L1 according to the first command signal received from the control unit 501, and transmits the current threshold L1 to the first current comparing unit 509. The second current threshold setting unit 505 generates a current threshold L2 according to the second command signal received from the control unit 501, and transmits the current threshold L2 to the second current comparing unit 511. The reference value setting unit 507 generates a reference value K1 according to the third command signal received from the control unit 501, and transmits the reference value K1 to the differential value comparing unit 515.

[0086] The first current comparing unit 509 compares the signal of the current value Icv measured by the current measuring unit 30 with the current threshold L1 from the first current threshold setting unit 503, generates a first current level determination signal based on the comparison result, and transmits the first current level determination signal to the determining unit 517. The first current level determination signal corresponds to the "current level determination signal" described in the first and second embodiments. Therefore, the first current comparing unit 509 generates a first current level determination signal that is valid (for example, high level) when the current value Icv is equal to or greater than the current threshold L1, and generates a first current level determination signal that is invalid (for example, low level) when the current value Icv is less than the current threshold L1.

[0087] The second current comparing unit 511 compares the signal of the current value Icv with the current threshold L2 from the second current threshold setting unit 505, generates a second current level determination signal based on the comparison result, and transmits the second current level determination signal to the control unit 501. The second current comparing unit 511 generates a second current level determination signal that is valid (e.g., high level) when the current value Icv is equal to or greater than the current threshold L2, and generates a second current level determination signal that is invalid (e.g., low level) when the current value Icv is less than the current threshold L2. For example, when the control unit 501 receives a high-level second current level determination signal, it transmits a timing signal to the determination unit 517 after a predetermined time has elapsed since the control unit 501 received the high-level second current level determination signal.

[0088] The differential calculation unit 513 calculates a current differential value Icdi of the current value Icv. The differential value comparison unit 515 compares the current differential value Icdi with a reference value K1 from the reference value setting unit 507, generates an Ic decrease rate determination signal based on the comparison result, and transmits the Ic decrease rate determination signal to the determination unit 517. The differential value comparison unit 515 generates an Ic decrease rate determination signal that is valid (for example, high level) when the current differential value Icdi is less than the reference value K1, and that is invalid (for example, low level) when the current differential value Icdi is equal to or greater than the reference value K1.

[0089] When the determination unit 517 receives a timing signal from the control unit 501, it activates the differential detection enable signal. Furthermore, during the period in which the differential detection enable signal is active, the determination unit 517 determines whether or not the test object 10 has been destroyed based on the first current level determination signal and the Ic decrease rate determination signal. Specifically, the determination unit 517 determines that the test object 10 has been destroyed if the current value Icv is equal to or greater than the current threshold L1 (i.e., the first current level determination signal is active) at the timing when the current differential value Icdi changes from less than the reference value K1 to equal to or greater than the reference value K1 (i.e., the Ic decrease rate determination signal changes from active to inactive). In this case, the determination unit 517 outputs an interruption signal to the current interruption unit 60.

[0090] 9 shows a functional configuration corresponding to the destruction detection method according to the first embodiment, but is not limited to this. The destruction detection unit 50 may have a functional configuration corresponding to the destruction detection method according to the second embodiment.

[0091] In this case, the control unit 501 transmits a fourth command signal to the reference value setting unit 507 to instruct the reference value setting unit 507 to generate the reference value K2. The reference value setting unit 507 generates the reference value K2 according to the fourth command signal and transmits the reference value K2 to the differential value comparison unit 515.

[0092] The differential calculation unit 513 calculates a voltage differential value Vcedi of the voltage value Vcev. The differential value comparison unit 515 compares the voltage differential value Vcedi with a reference value K2 from the reference value setting unit 507, generates a Vce decrease rate determination signal based on the comparison result, and transmits the Vce decrease rate determination signal to the determination unit 517. The differential value comparison unit 515 generates a Vce decrease rate determination signal that is valid (for example, high level) when the voltage differential value Vcedi is less than the reference value K2, and that is invalid (for example, low level) when the voltage differential value Vcedi is equal to or greater than the reference value K2.

[0093] The determination unit 517 determines whether the test object 10 has been broken down based on the first current level determination signal and the Vce decrease rate determination signal during the period in which the differential detection enable signal is valid. Specifically, the determination unit 517 determines that the test object 10 has been broken down if the current value Icv is equal to or greater than the current threshold L1 (i.e., the first current level determination signal is valid) at the timing when the voltage differential value Vcedi changes from equal to or greater than the reference value K2 to less than the reference value K2 (i.e., the Vce decrease rate determination signal changes from invalid to valid). In this case, the determination unit 517 outputs a blocking signal to the current blocking unit 60.

[0094] Furthermore, when the test apparatus 100 is actually used, other functional configurations may be added to the destruction detection unit 50 of FIG. 9 to fulfill other necessary functions.

[0095] 10 is a timing chart for explaining an example of a processing procedure of the test apparatus 100 according to the third embodiment. In FIG. 10, a timing chart is explained for the case where the test object 10 is broken in the electrical characteristics test using the breakdown detection unit 50 explained in FIG.

[0096] 10 , at the start of the test, semiconductor switch 64 is turned on by gate driver 62. Test voltage Vcc is output from power supply 22, and capacitor 24 is charged. At this time, voltage Vce is applied between the collector and emitter of test subject 10. Next, gate driver 90 applies voltage Vge to test subject 10 to turn test subject 10 on, causing current to flow from capacitor 24 through semiconductor switch 64 and load 70 to test subject 10.

[0097] The current Ic flowing through the test object 10 gradually increases, and at timing t1, the current value Icv becomes equal to or greater than the current threshold L1, at which point the first current level determination signal becomes active (e.g., high level). The current Ic further increases, and at timing t2, the breakdown detection unit 50 determines that the current value Icv is equal to or greater than the current threshold L2, at which point the second current level determination signal becomes active (e.g., high level). When the second current level determination signal becomes high level, a measurement sequence for turning off the test object 10 is activated.

[0098] When the measurement sequence is activated, the gate driver 90 reduces the voltage Vge applied to the test object 10. At this time, the control unit 501 of the breakdown detection unit 50 activates the differential detection enable signal and starts the operation of a timer for measuring the differential detection time T1.

[0099] As the test object 10 is turned off, the current Ic begins to decrease. As the current Ic decreases, the current differential value Icdi becomes less than the reference value K1 at timing t3. While the current Ic continues to decrease, the current differential value Icdi becomes a negative value. When the breakdown detection unit 50 determines that the current differential value Icdi is less than the reference value K1, the Ic decrease rate determination signal becomes valid (for example, high level).

[0100] Furthermore, let us assume that the current Ic continues to decrease, and at timing t6, the test subject 10 is destroyed. The decrease in the current value Icv stops as the test subject 10 is destroyed. At this time, the current differential value Icdi generated by the differential calculation unit 513 of the destruction detection unit 50 attempts to change from a negative value to a positive value. Therefore, the current differential value Icdi becomes equal to or greater than the reference value K1, and the Ic decrease rate determination signal becomes invalid (e.g., low level). Because the Ic decrease rate determination signal has become low level, the determination unit 517 of the destruction detection unit 50 activates the destruction determination period signal (e.g., high level). Based on the fact that the differential detection enable signal, the first current level determination signal, and the destruction determination period signal are all high level, the determination unit 517 determines that the test subject 10 has been destroyed. In response to this determination, the determination unit 517 outputs a shutdown signal to the current shutdown unit 60.

[0101] When the gate driver 62 of the current cutoff unit 60 receives the cutoff signal from the breakdown detection unit 50, it turns off the semiconductor switch 64. As the semiconductor switch 64 turns off, the current value Icv decreases, and at timing t7, the current value Icv becomes less than the current threshold L1, and the first current level determination signal becomes low level.

[0102] Thereafter, the current value Icv becomes 0 A. When the control unit 501 determines that the differential detection time T1 has elapsed since timing t2, the differential detection enable signal becomes low level, and the electrical characteristic test ends. Since the state of breakdown when the test object 10 is defective varies individually, it is uncertain which of the timing at which the current value Icv becomes 0 A or the timing at which the differential detection enable signal becomes low level occurs first.

[0103] The behavior of each signal being at a high level or a low level has been explained above using Figure 10, but this is just one example. As long as the logic of each state and each signal is set appropriately, and the actual determination does not change, each signal may be at a high level or a low level.

[0104] Fourth Embodiment In a fourth embodiment, a method for manufacturing a semiconductor device including an evaluation step using a test device according to the above-described embodiment will be described.

[0105] 11 is a flowchart showing a method for manufacturing a semiconductor device according to the fourth embodiment. Referring to FIG. 11, the method for manufacturing a semiconductor device includes a preparation step (step S11) of preparing a semiconductor element (e.g., an IGBT, a MOSFET, or the like), an evaluation step (step S12) of testing (evaluating) electrical characteristics of the semiconductor element using test apparatus 100, and a production step (step S13) of producing a semiconductor device including the evaluated semiconductor element. Here, examples of the semiconductor device include a semiconductor wafer, a chip-shaped semiconductor chip obtained by dicing, a module product incorporating a semiconductor chip therein, a discrete product, and the like.

[0106] In the preparation step of step S11, a semiconductor device is prepared as the test object 10. For example, in the preparation step, semiconductor devices in a wafer state are prepared. The semiconductor devices are manufactured by a wafer process.

[0107] In the evaluation step of step S12, the electrical characteristics of the prepared semiconductor device are evaluated. Specifically, an electrical characteristic test including breakdown detection of the test object 10 is performed using the test apparatus 100. In the evaluation step, the dynamic characteristics of the semiconductor device may be evaluated. Through the evaluation step, a semiconductor device whose electrical characteristics have been appropriately evaluated (e.g., passed the test) can be obtained.

[0108] In the production process of step S13, semiconductor devices including semiconductor elements that have passed the test in the evaluation process are commercialized. Typically, the production process includes a process of cutting semiconductor chips from a semiconductor wafer, a process of mounting the cut semiconductor chips on a substrate inside a module or discrete device, and other processes until the module or discrete device is completed. In this way, semiconductor devices including semiconductor elements that have passed the test can be manufactured.

[0109] In addition, when the semiconductor wafer after the wafer process or the semiconductor chip cut into chips from the semiconductor wafer is used as the product, the manufacturing process may include a process of making the semiconductor wafer or semiconductor chip that has passed the test into a state ready for shipping as a product. In this case, the manufactured semiconductor device is the semiconductor wafer or semiconductor chip in a state ready for shipping as a product.

[0110] In the above-described manufacturing method, steps other than the evaluation step using the test device 100 can be publicly known steps.

[0111] Other Embodiments. The configurations exemplified as the above-described embodiments are examples of the configurations of the present disclosure, and may be combined with other known technologies, or may be modified, such as by omitting some parts, within the scope of the gist of the present disclosure. Furthermore, the above-described embodiments may be implemented by appropriately adopting the processes and configurations described in other embodiments.

[0112] <Supplementary Notes> Various aspects of the present disclosure will be summarized below as supplementary notes.

[0113] (Supplementary Note 1) A testing apparatus comprising: a current measuring unit that measures a current value of a current flowing in a test object including a semiconductor element; a breakdown detection unit that detects breakdown of the test object; a semiconductor switch that is connected between a power supply unit and the test object and that cuts off the current flowing in the test object when breakdown of the test object is detected; and a load that is connected between the semiconductor switch and the test object, wherein the breakdown detection unit determines that the test object has been broken if the current value is equal to or greater than a first current threshold at a first timing when a differentiated value of the current value changes from less than a first reference value to equal to or greater than the first reference value.

[0114] (Supplementary Note 2) The test apparatus according to Supplementary Note 1, wherein the destruction detection unit determines that the test object is not destroyed if the current value is less than the first current threshold at the first timing.

[0115] (Supplementary Note 3) The test apparatus according to Supplementary Note 1 or Supplementary Note 2, wherein the first reference value is a value for detecting a decrease in the rate of decrease of the current when the current flowing through the test subject is reduced by controlling the test subject from an on state to an off state.

[0116] (Supplementary Note 4) A testing apparatus comprising: a current measuring unit that measures a current value of a current flowing in a test object including a semiconductor element; a voltage measuring unit that measures a voltage value of a voltage applied to the test object; a breakdown detecting unit that detects breakdown of the test object; a semiconductor switch that is connected between a power supply unit and the test object and that cuts off the current flowing in the test object when breakdown of the test object is detected; and a load that is connected between the semiconductor switch and the test object, wherein the breakdown detecting unit determines that the test object has been broken if the current value is equal to or greater than a first current threshold value at a second timing when a differentiated value of the voltage value changes from equal to or greater than a second reference value to less than the second reference value.

[0117] (Supplementary Note 5) The test apparatus according to Supplementary Note 4, wherein the second reference value is a value for detecting a drop in voltage applied to the test object.

[0118] (Supplementary Note 6) The test apparatus according to any one of Supplementary Notes 1 to 5, further comprising a switching control unit that controls a switching operation of the test subject, wherein the switching control unit increases the current value of the current flowing through the test subject by controlling the test subject to an ON state, and controls the test subject to an OFF state at a third timing when the current value becomes equal to or greater than a second current threshold that is greater than the first current threshold, and the breakdown detection unit performs an operation of detecting breakdown of the test subject during a period from the third timing until a specified time has elapsed.

[0119] (Supplementary Note 7) The test apparatus according to any one of Supplementary Notes 1 to 6, further comprising a diode connected in parallel with the load.

[0120] (Supplementary Note 8) A testing method using a test apparatus, the test apparatus including: a semiconductor switch connected between a power supply unit and an object under test including a semiconductor element, the semiconductor switch cutting off a current flowing through the object under test when breakdown of the object under test is detected; and a load connected between the semiconductor switch and the object under test, the testing method including the steps of measuring a current value of a current flowing through the object under test including a semiconductor element, and detecting breakdown of the object under test, the detecting step including the step of determining that the object under test has been broken if the current value is equal to or greater than a first current threshold at a first timing when a differentiated value of the current value changes from less than a first reference value to equal to or greater than the first reference value.

[0121] (Supplementary Note 9) A testing method using a test apparatus, the test apparatus including: a semiconductor switch connected between a power supply unit and an object under test including a semiconductor element, the semiconductor switch cutting off a current flowing through the object under test when breakdown of the object under test is detected; and a load connected between the semiconductor switch and the object under test, the testing method including the steps of measuring a current value of a current flowing through the object under test including a semiconductor element, measuring a voltage value of a voltage applied to the object under test, and detecting breakdown of the object under test, the detecting step including the step of determining that the object under test has been broken if the current value is equal to or greater than a first current threshold at a second timing when a differentiated value of the voltage value changes from equal to or greater than a second reference value to less than the second reference value.

[0122] (Supplementary Note 10) A method for manufacturing a semiconductor device, comprising the steps of: preparing a semiconductor element; evaluating characteristics of the semiconductor element using a test device according to any one of Supplementary Note 1 to Supplementary Note 7; and commercializing a semiconductor device including the evaluated semiconductor element.

[0123] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0124] 10 Test object, 20 Power supply unit, 22 Power supply, 24 Capacitor, 30 Current measurement unit, 40, 41 Voltage measurement unit, 50 Breakdown detection unit, 60 Current interruption unit, 62, 90 Gate driver, 64 Semiconductor switch, 70 Load, 82 Regenerative diode, 84 Diode, 100 Testing device, 501 Control unit, 503 First current threshold setting unit, 505 Second current threshold setting unit, 507 Reference value setting unit, 509 First current comparison unit, 511 Second current comparison unit, 513 Differential calculation unit, 515 Differential value comparison unit, 517 Determination unit.

Claims

1. A current measuring unit that measures the current value of the current flowing through a test subject including a semiconductor element, A destruction detection unit for detecting the destruction of the subject, The system includes a semiconductor switch connected between the power supply unit and the subject, which cuts off the current flowing to the subject when destruction of the subject is detected, The destruction detection unit determines that the test subject has been destroyed if, at a first timing when the differential value of the current value changes from less than a first reference value to or greater than the first reference value, the current value is greater than or equal to a first current threshold.

2. The test apparatus according to claim 1, wherein the destruction detection unit determines that the test subject is not destroyed if the current value is less than the first current threshold at the first timing.

3. The test apparatus according to claim 1 or claim 2, wherein the first reference value is a value for detecting a decrease in the rate of decrease of the current when the current flowing to the subject decreases as the subject is controlled from an ON state to an OFF state.

4. A current measuring unit that measures the current value of the current flowing through a test subject including a semiconductor element, A voltage measuring unit that measures the voltage value of the voltage applied to the subject, A destruction detection unit for detecting the destruction of the subject, The system includes a semiconductor switch connected between the power supply unit and the subject, which cuts off the current flowing to the subject when destruction of the subject is detected, The test apparatus includes a destruction detection unit which determines that the test subject has been destroyed when the current value is equal to or greater than a first current threshold at a second timing when the differential value of the voltage value changes from equal to or greater than a second reference value to less than the second reference value.

5. The test apparatus according to claim 4, wherein the second reference value is a value for detecting a decrease in the voltage applied to the subject.

6. The system further comprises a switching control unit that controls the switching operation of the subject, The switching control unit, By controlling the subject to be in the ON state, the current value of the current flowing through the subject is increased. At a third timing when the current value becomes greater than or equal to a second current threshold, which is greater than the first current threshold, the subject is controlled to an off state. The test apparatus according to claim 1 or 4, wherein the destruction detection unit performs a destruction detection operation of the test subject during the period from the third timing until after a specified time has elapsed.

7. The aforementioned test apparatus is A load connected between the semiconductor switch and the subject, The test apparatus according to claim 1 or claim 4, further comprising a diode connected in parallel to the load.

8. A test method using a test device, The test apparatus includes a power supply unit and a semiconductor switch connected between the test subject, which includes a semiconductor element, and which cuts off the current flowing to the test subject when damage to the test subject is detected. The aforementioned test method is The steps include: measuring the current value of the current flowing through the subject; The step includes detecting the destruction of the subject, The detection step includes a step of determining that the subject has been destroyed if, at a first timing when the differential value of the current value changes from less than a first reference value to or greater than the first reference value, the current value is greater than or equal to a first current threshold.

9. A test method using a test device, The test apparatus includes a power supply unit and a semiconductor switch connected between the test subject, which includes a semiconductor element, and which cuts off the current flowing to the test subject when damage to the test subject is detected. The aforementioned test method is The steps include: measuring the current value of the current flowing through the subject; The steps include measuring the voltage value of the voltage applied to the subject, The step includes detecting the destruction of the subject, A test method comprising the step of determining that the subject has been destroyed if, at a second timing when the differential value of the voltage value changes from greater than or equal to a second reference value to less than or equal to the second reference value, the current value is greater than or equal to a first current threshold.

10. The test method according to claim 8 or 9, wherein the test apparatus further includes a load connected between the semiconductor switch and the test subject, and a diode connected in parallel to the load.

11. The process of preparing semiconductor devices, A step of evaluating the characteristics of the semiconductor device using the test apparatus described in claim 1 or claim 4, A method for manufacturing a semiconductor device, comprising the step of commercializing a semiconductor device including the evaluated semiconductor element.