JP2008164629A - Temperature measuring method of semiconductor device, and temperature measuring device of semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a temperature measuring method of a semiconductor device and a temperature measuring device of the semiconductor device capable of detecting a joining temperature of the semiconductor device accurately without delay. <P>SOLUTION: In this temperature measuring method of the semiconductor device, the joining temperature of SiC GTO is determined by utilizing the fact that a rising time tv of a voltage Vak between an anode and a cathode as a turn-off characteristic time of SiC GTO which is a semiconductor switching element has high temperature dependency. The rising time tv is defined, for example, as a time required for the voltage Vak to reach 90% from 10% of a peak value. Namely, in the temperature measuring method, a measured turn-off characteristic time is converted into the joining temperature of SiC GTO based on a relation characteristic between the rising time tv measured beforehand and the joining temperature. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a temperature measuring method and a temperature measuring device for a semiconductor switching element such as a GTO (gate turn-off thyristor).

  Conventionally, as a method of measuring the temperature of the junction of the semiconductor device, there is a method of measuring the temperature of the junction by bringing a thermosensitive element such as a thermocouple into direct contact with the junction of the semiconductor device. As another measurement method, the temperature dependence of the on-voltage with respect to a predetermined current of the semiconductor device as shown in FIG. 11 is examined in advance, and the junction temperature of the semiconductor device is obtained indirectly from the value of the on-voltage. The method is used.

  Conventionally, inspection of a semiconductor device incorporated in an inverter is performed by measuring a resistance value between each terminal of a diode or a semiconductor switching element during periodic inspection of the inverter. By measuring the resistance value of the semiconductor device, the presence or absence of an abnormality of the semiconductor device is determined, and appropriate measures such as replacement of the semiconductor device have been taken based on the determination of the presence or absence of the abnormality.

  By the way, in the former method in which a thermosensitive element such as a thermocouple is brought into direct contact with the junction of the semiconductor device and the temperature of the junction is measured, it is necessary to open the package of the semiconductor device as a specimen and attach the thermal element. is there. Due to the attachment of the thermal element, the measurement of the temperature of the junction in the energized state becomes a limitation of electrical insulation, and further, the thermal element becomes an endothermic source and an error occurs in the temperature measurement of the junction of the semiconductor device. There were drawbacks such as Further, since the temperature detection by the thermal element cannot catch up with the actual temperature rise rate of the junction, there is a problem that the junction temperature detected by the thermal element cannot be used for heating protection of the semiconductor device.

  In addition, the latter method of measuring the junction temperature indirectly using the temperature dependence of the on-voltage is essentially free from the temperature dependence of the on-voltage due to the structure of the semiconductor device to be measured. Measurement is impossible, and the measurement accuracy deteriorates when the temperature change of the measurement object is small. For this reason, the application range of the semiconductor device to be measured has been limited.

  As illustrated in FIG. 12, a bipolar semiconductor device using a wide gap semiconductor such as SiC, gallium nitride, and diamond that can be used up to a temperature significantly higher than about 125 ° C., which is a use limit temperature of a conventional Si semiconductor device, From a low temperature to about 200 ° C., the ON voltage gradually decreases as the temperature rises.

  However, as illustrated in FIG. 12, the on-voltage of the bipolar semiconductor device using these wide gap semiconductors has almost no temperature dependency when the junction temperature is 200 ° C. or higher. When the junction temperature is further increased, the on-voltage increases. In the case of such a semiconductor device, it is impossible to measure the junction temperature of 200 ° C. or higher with high accuracy, or even if it can be measured, the accuracy is very poor.

  In addition, when the semiconductor device to be measured is a high-power semiconductor device having a press-contact structure, and the junction temperature of the high-power semiconductor device is obtained using the temperature dependence of the on-voltage, the change in the on-voltage is the entire surface of the junction to be measured May not adequately reflect the average junction temperature over. This occurs because a change in the pressure contact force in the pressure contact structure changes the contact resistance of the internal electrode, or the measurement current for obtaining the on-voltage does not flow uniformly throughout the semiconductor device to be measured. . Furthermore, when the current changes instantaneously, it is difficult to discriminate between a change in voltage caused by the change in current and a change in voltage caused by a change in junction temperature. .

Furthermore, the life of the inverter components depends greatly on the ambient temperature and usage conditions. Deterioration of these parts often proceeds more rapidly than a certain time, and in the conventional periodic inspection, the abnormality of the parts cannot be found and the inverter device may be broken. In the case of a diode or a semiconductor switching element incorporated in an inverter, it is often impossible to determine an abnormality or a failure by simply checking the resistance value between the terminals.
JP 05-215809 A Japanese Patent No. 3054404

  SUMMARY OF THE INVENTION An object of the present invention is to provide a temperature measuring method for a semiconductor device and a temperature measuring device for the semiconductor device that can accurately detect the junction temperature of the semiconductor device without delay.

In order to solve the above-described problem, a semiconductor device temperature measurement method according to the present invention sets a semiconductor switching element to a predetermined temperature, turns off the semiconductor switching element that has reached the predetermined temperature from an on state, and performs the turn-off. A first step of performing a characteristic measurement for measuring a predetermined turn-off characteristic time at a plurality of times by changing the temperature a plurality of times and measuring in advance a relational characteristic between the turn-off characteristic time and the temperature of the semiconductor switching element;
A second step of turning off the semiconductor switching element from an on state and measuring the turn-off characteristic time at the turn-off;
A third step of converting the turn-off characteristic time measured in the second step into a temperature of the semiconductor switching element based on the relationship characteristic measured in advance in the first step;
The semiconductor switching element is a GTO,
The turn-off characteristic time is
It is characterized by the rise time of the anode-cathode voltage.

  According to the temperature measurement method of the present invention, the temperature of the semiconductor switching element is obtained by utilizing the fact that the turn-off characteristic time of the semiconductor switching element is highly temperature dependent. That is, according to the present invention, the turn-off characteristic time measured in the second step based on the relational characteristic between the turn-off characteristic time and temperature of the semiconductor switching element measured in the first step in advance is used as the semiconductor switching element. It is converted to the temperature. Therefore, according to the present invention, the junction temperature of the semiconductor device can be detected accurately and without delay.

In one embodiment, the semiconductor switching element is a bipolar semiconductor element.
In the temperature measurement method for a semiconductor device according to a reference example, the semiconductor switching element is a GTO, and the turn-off characteristic time is an accumulation time from the rise start time of the gate turn-off current to the decay start time of the anode current.

  According to the temperature measurement method of the semiconductor device of this reference example, the temperature (junction temperature) of the GTO can be accurately measured by measuring the accumulation time of the GTO as the semiconductor switching element.

  In one embodiment, the semiconductor switching element is a GTO, and the turn-off characteristic time is the rise time of the anode-cathode voltage.

  According to the temperature measurement method of the semiconductor device of this embodiment, the temperature (junction temperature) of the GTO can be accurately measured by measuring the rise time of the voltage between the anode and the cathode of the GTO as the semiconductor switching element.

  In the temperature measurement method for a semiconductor device according to a reference example, the semiconductor switching element is a GTO, and the turn-off characteristic time is an anode current decay time.

According to the temperature measuring method of the semiconductor device of this reference example, the temperature (junction temperature) of the GTO can be accurately measured by measuring the decay time of the anode current of the GTO as the semiconductor switching element.
In one embodiment, the semiconductor switching element is a SiC GTO. In particular, it has been found through experiments that the turn-off characteristics of SiC GTO are highly dependent on the junction temperature.
In one embodiment, the semiconductor switching element is a GaN GTO.
In one embodiment, the semiconductor switching element is a diamond GTO.

A temperature measuring device for a semiconductor device according to an embodiment is a measuring device that measures the temperature of the semiconductor device using the temperature measuring method for the semiconductor device,
A DC power source for applying a DC voltage between the output terminals of the semiconductor switching element;
A control circuit for inputting a control signal to a control terminal of the semiconductor switching element to turn the semiconductor switching element on and off; and
A waveform measurement unit for measuring a turn-off waveform of the semiconductor switching element;
A waveform calculation unit that calculates a predetermined turn-off characteristic time based on the turn-off waveform measured by the waveform measurement unit;
The semiconductor switching corresponding to the turn-off characteristic time inputted from the waveform calculation unit and storing data representing a relational characteristic between the turn-off characteristic time of the semiconductor switching element and the temperature of the semiconductor switching element measured in advance. A temperature calculation unit that obtains the temperature of the element from the relational characteristics.

  According to the temperature measuring device for a semiconductor device of this embodiment, the semiconductor switching element is turned off by the control circuit, the turn-off waveform is measured by the waveform measuring unit, and the turn-off characteristic time is calculated from the turn-off waveform by the waveform calculating unit. The temperature calculation unit obtains the temperature of the semiconductor switching element corresponding to the turn-off characteristic time input from the waveform calculation unit from the relationship characteristic between the turn-off characteristic time and the temperature measured in advance. Therefore, according to this embodiment, the junction temperature of the semiconductor device can be detected accurately and without delay.

  In one embodiment, the waveform measuring unit includes an output voltage measuring unit that measures a voltage between the output terminals of the GTO.

  According to the temperature measuring device for a semiconductor device of this embodiment, the output voltage turn-off waveform can be measured by the output voltage measuring unit as the waveform measuring unit.

Moreover, the thermal resistance measurement method of the semiconductor device of one reference example is a method of measuring the thermal resistance of the semiconductor device using the temperature measurement method of the semiconductor device,
A first measurement step of measuring in advance the relationship between the turn-off characteristic time of the semiconductor switching element and the temperature of the semiconductor switching element by the first step;
A first temperature of the semiconductor switching element is measured, then the semiconductor switching element is turned on, and after a predetermined time has elapsed since the turning on, the semiconductor switching element is turned off, and the second, second, A second measuring step of measuring the second temperature of the semiconductor switching element by the step of 3,
A value obtained by subtracting the first temperature from the second temperature by the amount of heat generated by the semiconductor switching element at the predetermined time is calculated as a thermal resistance.

  According to the method for measuring the thermal resistance of the semiconductor device of this reference example, the thermal resistance is calculated from the loss (heat generation amount) during the ON period in the second measurement step and the temperature rise from the first temperature to the second temperature. The thermal resistance can be detected with high accuracy even at a high temperature (for example, 200 ° C. or more for a wide gap semiconductor). In addition, the measurement of the first temperature in the second measurement step may be measured by a contact thermometer as an example, and by the second and third steps of the temperature measurement method of the semiconductor device of the present invention, It is also possible to measure.

Further, a thermal resistance measuring device for a semiconductor device according to a reference example is a device for measuring the thermal resistance of a semiconductor device using the above thermal resistance measuring method, and a DC voltage via a load between output terminals of the semiconductor switching element. A DC power supply for applying
An on control signal is input to the control terminal of the semiconductor switching element to turn on the semiconductor switching element from an off state, and after a predetermined time has elapsed since the semiconductor switching element was turned on, the off control signal is applied to the control terminal. And a control circuit for turning off the semiconductor switching element,
A waveform measuring unit for measuring the waveform of the turn-off of the semiconductor switching element;
A waveform calculation unit that calculates a predetermined turn-off characteristic time based on the waveform of the turn-off measured by the waveform measurement unit;
Data representing a relational characteristic between the turn-off characteristic time of the semiconductor switching element measured in advance and the temperature of the semiconductor switching element is stored, and the data corresponding to the predetermined turn-off characteristic time input from the waveform calculation unit A temperature calculation unit for obtaining the temperature of the semiconductor switching element from the above-mentioned relationship characteristics;
The value obtained by subtracting the temperature of the semiconductor switching element before being turned on by the control circuit from the temperature of the semiconductor switching element obtained by the temperature calculation unit is the amount of heat generated by the semiconductor switching element during the predetermined time. And a thermal resistance calculator that calculates the divided value as thermal resistance.

  According to the thermal resistance measuring apparatus of this reference example, the control circuit turns on and off the semiconductor switching elements sequentially from the off state, and measures the turn-off waveform in the waveform measuring unit. The waveform calculation unit calculates a predetermined turn-off characteristic time based on the turn-off waveform, and the temperature calculation unit obtains the temperature of the semiconductor switching element from the turn-off characteristic time. The thermal resistance calculation unit subtracts a value obtained by subtracting the temperature of the semiconductor switching element before being turned on by the control circuit from the temperature of the semiconductor switching element obtained by the temperature calculation unit at the predetermined time. A value divided by the amount of heat generated by the element is calculated as the thermal resistance. Thereby, the thermal resistance of the semiconductor switching element can be detected with high accuracy even at a high temperature (for example, 200 ° C. or more for a wide gap semiconductor).

  In addition, the semiconductor device degradation status evaluation method of one reference example can evaluate the degradation status of the semiconductor device based on the thermal resistance measured by the thermal resistance measurement method.

  According to the temperature measuring method for a semiconductor device of the present invention, the temperature of the semiconductor switching element is obtained by utilizing the fact that the turn-off characteristic time of the semiconductor switching element has a large temperature dependency. That is, according to the present invention, the turn-off characteristic time measured in the second step is converted into the temperature of the semiconductor switching element based on the relationship between the turn-off characteristic time and the temperature measured in advance in the first step. Yes. Therefore, according to the present invention, the junction temperature of the semiconductor device can be detected accurately and without delay.

  Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

(First embodiment)
With reference to FIGS. 1-3, the temperature measuring method of the semiconductor device as 1st Embodiment of this invention is demonstrated. The first embodiment is a method for detecting a junction temperature of a SiC GTO (gate turn-off thyristor) as an example of a semiconductor switching element without delay. FIG. 3 shows an example of a GTO structure. In FIG. 3, 1 is a gate, 2 is a cathode, 3 is an anode, 4 is a P emitter, 5 is an N base, 6 is a P base, and 7 is an N emitter.

  In the GTO, when the potential of the anode 3 is higher than the potential of the cathode 2 and the potential of the gate 1 is made lower than the potential of the anode 3 and a forward bias voltage is applied between the anode 3 and the gate 1, When a turn-on current flows through 1 and further a current flows from the anode 3 to the cathode 2, the turn-on current is turned on.

  When a reverse bias voltage is applied between the anode 3 and the gate 1 in this ON state, an electron flow flowing from the cathode 2 to the anode 3 or a hole flowing from the anode 3 to the cathode 2 is shunted to the gate 1 to cause gate turn-off. A current flows and the GTO is turned off.

  FIG. 1 shows a current voltage waveform when the GTO is turned off. In FIG. 1, Ia is an anode current, Vak is an anode-cathode voltage, and Ig is a gate turn-off current. In FIG. 1, ts is called an accumulation time. The accumulation time ts is a time from the rising start time t1 of the gate turn-off current Ig to the decay start time t2 of the anode current Ia when the GTO is switched from the on state to the off state by the gate turn-off current Ig.

  The rising start time t1 of the gate turn-off current Ig is, for example, the time when the gate turn-off current Ig reaches 10% of the peak value of the gate turn-off current Ig. Further, the decay start time t2 of the anode current Ia is, for example, the time when the anode current Ia reaches a value 0.9Iak that is 10% lower than the maximum value Iak. The rising start time t1 is not limited to the time when the gate turn-off current Ig reaches 10% of the peak value of the gate turn-off current Ig, and is less than 10% of the peak value (for example, 3% Or 5% or 8%), or 10% or more of the peak value (for example, 12% or 15%). Further, the decay start time t2 is not limited to the time when the anode current Ia becomes a value 0.9Iak which is 10% lower than the maximum value Iak, and a value exceeding 10% from the maximum value Iak ( For example, it may be a time point when it has fallen by 12% or 15%), or may be a time point when it has fallen by a value that does not reach 10% from the maximum value Iak (for example, 5% or 8%).

  As shown in FIG. 2, the accumulation time ts has a large temperature dependence with respect to the GTO junction temperature. FIG. 2 is a graph showing the relationship between the GTO junction temperature and the storage time ts.

  By the way, in the case of SiC, Al, B, etc. used as p-type impurities have deep acceptor levels, and only a part of them is ionized when the temperature is low, but the ionization rate increases as the temperature rises. Since the GTO has a four-layer structure of pnpn (p emitter, n base, p base, n emitter), in the case of GTO using a semiconductor with a deep acceptor level, the p-type hole density increases at a high temperature. Become high. When the hole density of the p emitter of the GTO increases, the number of holes injected from the p emitter through the n base to the p base increases when the GTO is turned on. At this time, electrons are injected from the n emitter into the p base due to the neutral condition of electric charge, and thus the carriers in the p base increase. In addition, the lifetime of the minority carrier increases as the temperature increases. Due to these effects, when the temperature increases, the surplus carriers in the p base increase, and the accumulation time ts during turn-off increases.

  Therefore, in one reference example, the GTO junction temperature is detected (third step) by measuring the accumulation time ts when the GTO is turned off (second step). For this purpose, the temperature dependence of the accumulation time ts as shown in the relational characteristic diagram of FIG. 2 needs to be measured in advance (first step).

  As an example, the temperature dependence of the accumulation time ts is measured as follows.

  A semiconductor device is constituted by the GTO and a package that accommodates the GTO. The package that accommodates the GTO is heated by a heater or placed in a thermostatic bath, and the temperature of the GTO package is a predetermined temperature. Wait until it stabilizes. When this temperature is stabilized, the GTO bonding temperature is also stabilized at the predetermined temperature. At this stable point, the GTO is turned on for a predetermined time and then turned off. The predetermined time to be turned on is set to a short time (for example, about 10 μs to 200 μs) such that the GTO bonding temperature does not increase.

  Then, as described above, the accumulation time ts is measured from the waveforms of the gate turn-off current Ig and the anode current Ia at the time of off as illustrated in FIG. The accumulation time ts is measured at a plurality of different temperatures of the GTO package. As a result, the relationship characteristic (temperature dependence characteristic) between the GTO accumulation time ts and the junction temperature as illustrated in FIG. 2 is obtained. The measurement of the relational characteristic forms the first step.

  The temperature dependence characteristic of the accumulation time ts as shown in FIG. 2 is used as a conversion curve for converting the measured accumulation time ts into the GTO junction temperature. That is, the accumulation time ts reflects the GTO junction temperature. Therefore, by using the conversion curve, the junction temperature of the GTO can be detected without a time delay from the accumulation time ts. Further, since the temperature dependence of the accumulation time ts is large, the GTO junction temperature can be accurately measured. Therefore, the GTO rating can be determined stably with high reliability. Further, in the GTO intermittent operation test and the like, the GTO junction temperature can be measured with high accuracy and high responsiveness.

In the above reference example, the GTO junction temperature was measured using the temperature dependence characteristics of the GTO accumulation time ts as shown in FIG. 1, but the GTO anode-cathode voltage Vak shown in FIG. A relational characteristic (dependence characteristic) between the rise time tv and the temperature may be used for conversion of the GTO junction temperature. This case is an embodiment of the present invention. The rise time tv of the anode-cathode voltage Vak is, for example, the time from when the voltage Vak reaches 10% of the peak value until it reaches 90%. FIG. 4 shows an example of a relational characteristic (temperature dependence characteristic) between the rise time tv of the GTO anode-cathode voltage Vak and the temperature. Moreover, you may utilize the temperature dependence characteristic of the decay time ti of the anode current Ia of GTO shown in FIG. 1 for conversion of the junction temperature of GTO. The decay time ti of the anode current Ia is, for example, a time from when the anode current Ia is 90% of the maximum value Iak to when it is reduced to 10%. FIG. 5 shows a relational characteristic (temperature dependence characteristic) between the decay time ti of the anode current Ia of the GTO and the temperature.
The rise time tv of the anode-cathode voltage Vak is not limited to the time from when the voltage Vak reaches 10% of the peak value until it reaches 90%, but from when the voltage Vak reaches 5% until it reaches 95%. Of course, it is possible to set in various ranges such as the time of 15% of the peak value and the time to reach 85%. The decay time ti of the anode current Ia is not limited to the time from when the anode current Ia is 90% of the maximum value Iak to 10% but reaches 5% from the peak value of 95%. Of course, it is possible to set in various ranges such as the time to 85% of the peak value and the time to reach 15%.

  Further, as described above, the accumulation time ts is defined as the time from when the gate turn-off current Ig rises to when the anode current Ia starts to decrease. However, no CT (current transformer) can be mounted on the gate wiring. In this case or when the inductance of the gate wiring becomes a problem, the storage time ts may be obtained by measuring the gate voltage with a gate voltage measuring unit (not shown) as a control voltage measuring unit. For example, the time from the rise of the gate reverse voltage to the time when the anode-cathode voltage Vak becomes equal to the power supply voltage is defined as the accumulation time, and the temperature dependency of this accumulation time is used as a conversion curve for the junction temperature of the GTO. Also good.

  In the above embodiment, the case where the semiconductor switching element is a SiC GTO has been described. However, a semiconductor having a large temperature dependency of each waveform during a turn-off period, such as a SiC bipolar semiconductor element, for example, a SiC IGBT (insulated gate bipolar transistor). The switching element is a reference example. In addition, the present invention can be applied to other GTOs as well as SiC GTOs, but is a reference example in other bipolar semiconductor devices.

(Second embodiment)
Next, a temperature measuring device for a semiconductor device as a second embodiment of the present invention will be described with reference to FIGS.

  The junction temperature measuring device 30 includes a DC power supply 31, a capacitor 32 connected in parallel with the DC power supply 31, a first terminal 33, a second terminal 34, and a third terminal 35. A load reactor 36 and a first transformer 38 serving as an output current measuring unit are connected in series between the first terminal 33 and one end of the DC power supply 31. The third terminal 35 is connected to the other end of the DC power supply 31. A reflux diode 37 is connected in parallel with the load reactor 36.

  Further, a voltmeter 40 as an output voltage measuring unit is connected between the first terminal 33 and the third terminal 35. One end of the gate circuit 41 is connected to the first terminal 33, and the other end of the gate circuit 41 is connected to the second terminal 34. A second transformer 42 as a control current measuring unit is connected between the other end of the gate circuit 41 and the second terminal 34.

  On the other hand, the first connection member 43 is connected to the first terminal 33, the second connection member 44 is connected to the second terminal 34, and the third connection member 45 is connected to the third terminal 35. The first connection member 43 is connected to the cathode 47a of the SiC GTO 47 as the junction temperature measurement target, the second connection member 44 is connected to the gate 47b of the SiC GTO 47, and the third terminal 35 is connected to the anode 47c of the SiC GTO 47. Connected. The DC power supply 31 is connected in a direction in which a positive voltage is applied to the anode 47 c side of the GTO 47.

  As shown in the block diagram of FIG. 7, the junction temperature measuring device 30 includes the DC power supply 31, the temperature sensor unit 50, the control circuit 51, the waveform measuring unit 52, the waveform recording unit 53, the waveform calculating unit 54, and the temperature calculation. A time comparator 55 and a temperature display (recording) unit 56 are provided. The temperature sensor unit 50 includes the gate circuit 41, first to third terminals 33 to 35, and first to third connection members 43 to 45. The waveform measuring unit 52 includes the first transformer 38, the second transformer 42, and the voltmeter 40.

  Next, the operation of the bonding temperature measuring apparatus 30 will be described with reference to the flowchart of FIG.

  First, in step S1, the anode is connected between the anode 47c and the cathode 47a of the SiC GTO 47 via the first terminal 33, the third terminal 35, the first connecting member 43, and the third connecting member 45 from the DC power source 31. A DC voltage that is positive on the 47c side is applied.

  Next, in step S2, the control circuit 51 controls the gate circuit 41 of the temperature sensor unit 50, and sends an ON control signal from the gate circuit 41 to the gate 47b of the GTO 47 via the second terminal 34 and the second connection member 44. Input the GTO 47 to turn it on. As a result, a current flows from the DC power supply 31 to the load reactor 36 via the third terminal 35, the GTO 47, and the first terminal 33.

  Thereafter, after a predetermined short time has elapsed, the process proceeds to step S3, where the control circuit 51 controls the gate circuit 41 and inputs an off control signal from the gate circuit 41 to the gate 47b of the GTO 47 to turn off the GTO 47. .

  The predetermined short time is, for example, a time until the current flowing through the load reactor 36 reaches a predetermined value. That is, the ON time of the GTO 47 is set to a sufficiently short time so that the junction temperature does not increase due to the ON current. The current flowing through the load reactor 36 is detected by using the first transformer 38 included in the waveform measuring unit 52.

  Next, proceeding to step S4, the waveform measuring unit 52 measures the gate turn-off current Ig as exemplified in FIG. Further, the waveform measuring unit 52 measures the anode current Ia that is an output current as illustrated in FIG. 1 by the first transformer 38. In addition, the waveform measuring unit 52 measures the anode-cathode voltage Vak, which is an output voltage as exemplified in FIG. At this time, the gate circuit 41 may measure the gate voltage.

  The gate turn-off current Ig, the anode current Ia, and the anode-cathode voltage Vak measured by the waveform measuring unit 52 are input to the waveform recording unit 53, and the waveform of the gate turn-off current Ig, the turn-off waveform of the anode current Ia, and between the anode and cathode A turn-off waveform of voltage Vak is recorded. Then, the turn-off waveform recorded by the waveform recording unit 53 is input to the waveform calculation unit 54.

  This waveform calculation unit 54 calculates the accumulation time ts described in the first embodiment based on the waveform of the gate turn-off current Ig and the turn-off waveform of the anode current Ia input from the waveform recording unit 53, Input to the time comparator 55. The time comparator 55 stores in advance data representing a relational characteristic between the accumulation time ts illustrated in FIG. 2 and the junction temperature of the GTO 47. The relational characteristic (temperature dependent characteristic) between the accumulation time ts and the junction temperature is measured in advance in the same manner as described in the first embodiment.

  The waveform calculator 54 calculates the rise time tv of the anode-cathode voltage Vak described in the first embodiment from the turn-off waveform of the anode-cathode voltage Vak input from the waveform recording unit 53. To the time comparator 55. The time comparator 55 stores in advance data representing the relationship between the voltage rise time tv illustrated in FIG. 4 and the junction temperature of the GTO 47. The relational characteristic between the voltage rise time tv and the junction temperature is measured in advance, as is the relational characteristic between the accumulation time ts and the junction temperature.

  The waveform calculation unit 54 calculates the decay time ti of the anode current Ia described in the first embodiment from the waveform of the anode current Ia input from the waveform recording unit 53, and supplies the time comparator 55 with the decay time ti. input. The time comparator 55 stores in advance data representing the relationship between the current decay time ti and the junction temperature of the GTO 47 illustrated in FIG. The relational characteristic between the current decay time ti and the junction temperature of the GTO 47 is measured in advance, as is the relational characteristic between the accumulation time ts and the junction temperature.

  Next, the process proceeds to step S5, where the time comparator 55 compares the storage time ts input from the waveform calculation unit 54 with the data representing the relationship between the storage time and the junction temperature, and the input storage time. First data representing the junction temperature corresponding to ts is input to the temperature display (recording) unit 56.

  The time comparator 55 compares the rise time tv input from the waveform calculation unit 54 with data representing the relational characteristic between the voltage rise time tv and the junction temperature of the GTO 47, and determines the input rise time tv. Second data representing the corresponding junction temperature is input to the temperature display (recording) unit 56.

  In addition, the time comparator 55 compares the decay time ti of the anode current Ia input from the waveform calculation unit 54 with data representing the relational characteristics between the current decay time ti and the junction temperature of the GTO 47, and receives the input anode Third data representing the junction temperature corresponding to the decay time ti of the current Ia is input to the temperature display (recording) unit 56.

  Thereby, the temperature display (recording) part 56 displays and records the temperature according to the 1st-3rd data showing the said junction temperature. For example, the temperature display (recording) unit 56 may select one of the three data and display the temperature of the selected data, or display the average value of the temperatures of the three data. May be. Moreover, you may display the temperature of three data as it is.

  In this embodiment, three times having a relatively strong correlation with the junction temperature such as the accumulation time ts, the voltage rise time tv, and the current decay time ti are used, but at least the voltage rise time among them is used. The junction temperature may be obtained by selecting tv. Further, the junction temperature is determined by utilizing the relational characteristic between the time from when the gate reverse voltage measured by the gate circuit 41 rises until the anode-cathode voltage Vak becomes equal to the power supply voltage of the DC power supply 31 and the junction temperature. You may ask for it. In this embodiment, the reactor 36 is used as a load. However, instead of the reactor 36, a resistor or a series body of a reactor and a resistor may be used as a load. In this embodiment, a chopper circuit is used as the gate circuit 41. However, any circuit other than the chopper circuit can be applied as long as it is a circuit that energizes and shuts off the SiC GTO.

(Reference Example 1)
Next, a method for measuring the thermal resistance of a semiconductor device as Reference Example 1 of the present invention will be described. The thermal resistance measurement method of this reference example 1 utilizes the junction temperature measurement method of the first embodiment described above.

  In Reference Example 1, first, as shown in Step S11 of FIG. 9, in the same manner as described in the first embodiment, an SiC GTO (gate gate) as an example of a semiconductor switching element whose thermal resistance is to be measured. For each turn-off thyristor), from each turn-off waveform illustrated in FIG. 1 (gate turn-off current Ig, anode current Ia, anode-cathode voltage Vak), the accumulation time ts and the junction temperature illustrated in FIGS. The relationship characteristics between the voltage rise time tv and the junction temperature, the current decay time ti and the junction temperature are obtained.

Next, proceeding to step S12, first, the bonding temperature of the GTO is measured, and the measured bonding temperature is defined as a first bonding temperature T1. As an example, the measurement of the bonding temperature may be performed using a contact thermometer, or may be performed using the temperature measurement method of the first embodiment described above.
Next, as shown in the waveform diagram of FIG. 10, an ON control signal is input as a gate signal to the gate of the GTO to turn on the GTO. After a certain period of time t10 has passed since turning on, an off control signal is input as a gate signal to the gate of the GTO to turn off the GTO from the on state. From the turn-off waveform (gate turn-off current Ig, anode current Ia, anode-cathode voltage Vak) at the time of turn-off of the GTO, the junction temperature of the GTO is measured by the same method as in the first embodiment, and the measured junction The temperature is defined as a second bonding temperature T2.

  The junction temperature of the GTO rises by (T2−T1 = ΔT) by the anode-cathode voltage Vak applied to the GTO during the on-period t10. A value (ΔT / Q) obtained by dividing the increase amount ΔT of the junction temperature in the period t10 by the heat generation amount Q of the GTO in the period t10 is the thermal resistance.

  The heat generation amount Q of the GTO is calculated from the on period t10 (seconds), the anode-cathode voltage Vakon (V) during the on period t10, and the anode current Iak (A) during the on period t10. That is, the heat generation amount Q (J) = Vakon × Iak × t10.

  As described above, the accumulation time ts, the voltage rise time tv, and the current decay time ti in the turn-off waveform of the GTO as an example of the semiconductor switching element are highly dependent on the junction temperature. Therefore, according to the thermal resistance measurement method of this reference example, the thermal resistance of the GTO is measured with higher accuracy than in the case where the thermal resistance is calculated at the junction temperature obtained by using the temperature dependence of the conventional on-voltage. it can. In addition, the thermal resistance can be measured even at a high temperature where the ON voltage hardly depends on temperature. Furthermore, since the accumulation time ts (voltage rise time tv, current decay time ti) reflects the GTO junction temperature, the junction temperature can be measured without a time delay, and transient heat Resistance can be measured accurately. As the turn-off characteristic time, any one of the three times of the accumulation time ts, the voltage rise time tv, and the current decay time ti may be used, and three temperatures may be obtained from each characteristic time and averaged. Good.

(Reference example 2)
Next, a thermal resistance measuring apparatus as Reference Example 2 of the present invention will be described. The thermal resistance measurement apparatus of Reference Example 2 uses the thermal resistance measurement method of Reference Example 1 described above. In addition, the thermal resistance measuring device of the reference example 2 has a circuit in which a resistance is used instead of the load reactor 36 in the junction temperature measuring device 30 of the above-described second embodiment. Further, in this reference example 2, the time during which the GTO is turned on is longer than that of the junction temperature measuring device 30 of the second embodiment described above, and the on period t10 in the reference example 1 is set. During this on period t10, the GTO generates heat and the junction temperature is raised.

  In the thermal resistance measurement apparatus of Reference Example 2, the thermal resistance (ΔT / Q) of the GTO is calculated from the increase width ΔT of the junction temperature in the period t10 and the heat generation amount Q of the GTO in the period t10. The calculated thermal resistance is displayed on the display unit.

  According to the thermal resistance measuring apparatus of the reference example 2, it is possible to measure the thermal resistance with higher accuracy than the conventional apparatus that calculates the thermal resistance from the temperature dependence of the on-voltage. Further, the thermal resistance can be measured even at a high temperature where the ON voltage hardly depends on temperature.

(Reference Example 3)
Next, a semiconductor device deterioration state evaluation method as Reference Example 3 of the present invention will be described. This Reference Example 3 uses the thermal resistance measurement method of Reference Example 1 described above. That is, this reference example 3 evaluates the failure or deterioration state of this GTO according to the value of the GTO thermal resistance measured by the thermal resistance measurement method of reference example 1 described above.

  A semiconductor device is composed of a semiconductor chip and a package that form the GTO. If the adhesion between the semiconductor chip that forms the GTO and the package is poor, when the semiconductor device is energized, the junction temperature of the GTO is likely to increase. The accumulation time ts becomes longer. Accordingly, the thermal resistance increases. Further, when the adhesion between the semiconductor chip and the package deteriorates due to long-term use and partial peeling occurs, similarly, the junction temperature easily rises, the accumulation time ts becomes long, and the heat Resistance increases.

  In addition, the accumulation time ts may be shortened even when there is no problem in the adhesion between the semiconductor chip and the package. In this case, defects in the semiconductor chip increase and the minority carrier lifetime is shortened. In this case, the accumulation time ts is shorter than the initial value. In this case, in the thermal resistance measurement method of Reference Example 1 described above, if the initial temperature dependence curve with few defects is used as the temperature dependence curve of the accumulation time ts (FIG. 2), the measured junction temperature is the actual junction temperature. Lower than. For this reason, the thermal resistance calculated from the measured junction temperature is smaller than the initial thermal resistance. In other words, the degree of deterioration of the semiconductor chip (GTO) can be evaluated based on the amount of decrease in the value of the thermal resistance calculated from the measured junction temperature from the value of the thermal resistance calculated from the initially measured junction temperature. .

  Further, in the degradation status evaluation method of this reference example, a voltage is applied between the main electrodes (that is, between the anode and the cathode) of the semiconductor device, and the current flowing into the main electrode (that is, the anode current Ia) and the voltage between the main electrodes (that is, the anode). By measuring the anode-cathode voltage Vak) and its gate current or gate voltage, it is possible to grasp the deterioration state of the semiconductor device. Therefore, it is not necessary to remove the semiconductor device from the stack, and the period of periodic inspection can be shortened. In addition, the progress of deterioration can be grasped without removing the semiconductor device from the stack, and the semiconductor switching element can be replaced before the semiconductor switching element is destroyed, thereby preventing an unexpected accident. In addition, the progress of element deterioration can be grasped in advance, and elements can be prevented from being replaced more than necessary, thereby reducing costs.

  In the first and second embodiments and Reference Examples 1 to 3, the case where the semiconductor switching element is a SiC GTO has been described. However, a SiC bipolar semiconductor element other than the GTO, for example, a SiC IGBT (insulated gate bipolar transistor). A semiconductor switching element having a large temperature dependency of each waveform during the turn-off period is a reference example. In the first and second embodiments and Reference Examples 1 to 3, SiC is taken up as the wide gap semiconductor, but the present invention is also applicable to wide gap semiconductors such as gallium nitride and diamond. That is, this invention can be applied not only to SiC GTO but also to other GTOs such as GaN GTO and diamond GTO, and is a reference example in SiC bipolar semiconductor elements other than GTO and other bipolar semiconductor elements.

It is a wave form diagram which shows the turn-off waveform of SiC GTO demonstrated in 1st Embodiment of this invention. It is a characteristic view which shows the relationship between the accumulation | storage time as a turn-off characteristic time of the said SiC GTO demonstrated in the said 1st Embodiment, and junction temperature. It is a figure which shows the structure of the said SiC GTO typically. It is a figure which shows an example of the relational characteristic of the rise time tv of anode-cathode voltage Vak of said SiC GTO, and temperature. It is a figure which shows an example of the relationship characteristic of the decay time ti of the anode current Ia of the said SiC GTO, and temperature. It is a circuit diagram which shows the temperature measuring apparatus of the semiconductor device as 2nd Embodiment of this invention. It is a block diagram which shows the signal processing system | strain of the said 2nd Embodiment. It is a flowchart explaining operation | movement of the said 2nd Embodiment. It is process drawing explaining the thermal resistance measuring method of the semiconductor device as the reference example 1 of this invention. It is a wave form diagram explaining the said reference example 1. FIG. It is a figure which shows the relationship between the ON voltage of a semiconductor device utilized in a prior art example, and junction temperature. It is a figure which shows the relationship between the ON voltage of a bipolar semiconductor device using a wide gap semiconductor, and junction temperature.

Explanation of symbols

1 Gate 2 Cathode 3 Anode 4 P Emitter 5 N Base 6 P Base 7 N Emitter Ia Anode Current Vak Anode-Cathode Voltage Ig Gate Turn-off Current ts Accumulation Time t1 Rise Start Time t2 Decay Start Time 30 Junction Temperature Measuring Device 31 DC Power Supply 32 capacitor 33 first terminal 34 second terminal 35 third terminal 36 load reactor 37 freewheeling diode 38 first transformer 40 voltmeter 41 gate circuit 47 SiC GTO
47a Cathode 47b Gate 47c Anode 50 Temperature sensor unit 51 Control circuit 52 Waveform measurement unit 53 Waveform recording unit 54 Waveform calculation unit 55 Time comparator 56 Temperature display (recording) unit

Claims (6)

The semiconductor switching element is set to a predetermined temperature, the semiconductor switching element that has reached the predetermined temperature is turned off from the ON state, and the characteristic measurement for measuring the predetermined turn-off characteristic time at the turn-off time is performed by changing the temperature. A first step of measuring the relationship between the turn-off characteristic time and the temperature of the semiconductor switching element in advance a plurality of times,
A second step of turning off the semiconductor switching element from an on state and measuring the turn-off characteristic time at the turn-off;
A third step of converting the turn-off characteristic time measured in the second step into a temperature of the semiconductor switching element based on the relationship characteristic measured in advance in the first step;
The semiconductor switching element is a GTO,
The turn-off characteristic time is
A method for measuring a temperature of a semiconductor device, characterized by a rise time of an anode-cathode voltage. The temperature measurement method for a semiconductor device according to claim 1,
The method for measuring a temperature of a semiconductor device, wherein the semiconductor switching element is a SiC GTO. The temperature measurement method for a semiconductor device according to claim 1,
The method for measuring a temperature of a semiconductor device, wherein the semiconductor switching element is a GaN GTO. The temperature measurement method for a semiconductor device according to claim 1,
The method for measuring a temperature of a semiconductor device, wherein the semiconductor switching element is diamond GTO. A measuring apparatus for measuring the temperature of a semiconductor device using the temperature measuring method for a semiconductor device according to claim 1,
A DC power source for applying a DC voltage between the output terminals of the GTO;
A control circuit for inputting a control signal to the control terminal of the GTO to turn the GTO on and off;
A waveform measuring unit for measuring the GTO turn-off waveform;
A waveform calculation unit that calculates the rise time of the anode-cathode voltage as a predetermined turn-off characteristic time based on the turn-off waveform measured by the waveform measurement unit;
The GTO corresponding to the rise time inputted from the waveform calculation unit and storing data representing the relationship between the rise time of the anode-cathode voltage of the GTO measured in advance and the temperature of the GTO. A temperature measuring device for a semiconductor device, comprising: a temperature calculating unit that obtains the temperature of the semiconductor device from the relational characteristic. The temperature measuring device for a semiconductor device according to claim 5,
The waveform measurement unit
An apparatus for measuring a temperature of a semiconductor device, comprising: an output voltage measuring unit that measures a voltage between output terminals of the GTO.

Images