JP2017169145A - Semiconductor device, maintenance device, and maintenance method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control characteristic fluctuation by measuring parameters representing characteristic fluctuation of a semiconductor element, and then predicting the life of the semiconductor element based on the measurement results.SOLUTION: A semiconductor device 100 includes a semiconductor element 10 formed on a substrate having a polytype crystal structure, a measurement unit 20 including a first measurement section 21 for measuring the overshoot time of the gate voltage of the semiconductor element, and a second measurement section 22 for measuring the threshold voltage and ON voltage of the semiconductor element, a prediction unit 30 for predicting the life of the semiconductor element based on the measurement results from the measurement unit, and an adjustment unit 12 for changing the resistance value of a gate resistor Rg for connection to the gate G of the semiconductor element, based on the prediction results from the prediction unit. Life of the semiconductor element can be prolonged by changing the resistance value of a gate resistor in the adjustment unit, thereby adjusting the overshoot time of the gate voltage.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a semiconductor device, a maintenance device, and a maintenance method.

  In recent years, power semiconductor modules equipped with next-generation semiconductor devices such as silicon carbide compound semiconductor (SiC) devices and gallium nitride compound semiconductor (GaN) devices have been developed. SiC devices and GaN devices have a high breakdown voltage because they have higher breakdown field strength than conventional silicon semiconductor (Si) devices, and have a higher impurity concentration and a thinner active layer, resulting in high efficiency. In addition, a small power semiconductor module (also referred to as a semiconductor device) capable of high-speed operation can be realized.

  By providing a sensor that senses the operating state of a semiconductor element such as a current transformer (CT), Hall element, shunt resistor, magnetoresistive element, DESAT diode, thermistor, etc. The semiconductor module can be made intelligent. For example, Patent Document 1 is an intelligent inverter circuit equipped with a protection function, and when an overcurrent is detected by the protection function, the semiconductor element is turned off and the drive circuit and the circuit GND are short-circuited. An inverter circuit is disclosed that protects a semiconductor element that has been turned off from malfunctioning by a regenerative current generated by energy accumulated in a coil that constitutes the rotating motor from a rotating motor.

Patent Document 2 discloses an intelligent electronic control device including a plurality of switching elements, a multi-channel AD converter, and a series-parallel converter. In response to the determination signal, etc., they are controlled to open and close, and the energization current is read through the multi-channel AD converter and the serial-parallel converter, and is read at the time of closing drive regardless of the type of control signal for driving a plurality of opening / closing elements. An electronic control device in which the read timing is adjusted is disclosed. The series-parallel converter can reduce the number of wires between the electronic control unit and the microprocessor.
Patent Document 1 JP 2010-239760 A Patent Document 2 JP 2011-239550 A

  However, the inventor has found that the electrical characteristics of the SiC element, GaN element, and the like formed on the substrate having a polytype crystal structure such as SiC, GaN, etc. may be changed by repeated use. . Such characteristic fluctuations are gradually manifested by long-time driving such as several hundred hours or several thousand hours, and do not necessarily cause malfunction of the semiconductor element. The semiconductor element cannot be protected by suppressing the fluctuation. It is also difficult to screen a semiconductor element having such a characteristic variation as an initial failure.

  In a first aspect of the present invention, a semiconductor device comprising: a semiconductor element formed on a substrate having a polytype crystal structure; and a measurement unit that measures a parameter including an overshoot time of a gate voltage of the semiconductor element. Provided.

  In a second aspect of the present invention, a maintenance device for maintaining a semiconductor device including a semiconductor element, wherein a measurement unit that measures a parameter that serves as an index of characteristic variation of the semiconductor element, and the measured parameter are used. A maintenance device is provided that includes a prediction unit that predicts the lifetime of the semiconductor element.

  According to a third aspect of the present invention, there is provided a method for maintaining a semiconductor device including a semiconductor element, wherein a measurement step of measuring a parameter serving as an index of characteristic variation of the semiconductor element, and a semiconductor element using the measured parameter are measured. A maintenance method is provided comprising a prediction stage for predicting the lifetime.

  The summary of the invention does not enumerate all the features of the present invention. In addition, a sub-combination of these feature groups can also be an invention.

1 shows a configuration of a semiconductor device according to the present embodiment. An example of transient characteristics of a gate voltage input to a semiconductor element is shown. An example of a structure of a measurement part is shown. An example of the fluctuation | variation of the threshold voltage of a semiconductor element with respect to the operation time of a semiconductor device is shown. An example of the lifetime prediction and lifetime adjustment of a semiconductor element by the fluctuation | variation of a threshold voltage is shown. An example of the fluctuation | variation of the ON voltage of a semiconductor element with respect to the operation time of a semiconductor device is shown. 1 shows a configuration of a maintenance device for remotely monitoring a semiconductor device. The structure of the semiconductor device which concerns on the modification 1 and a maintenance apparatus is shown. The procedure of the maintenance method of the semiconductor device using the maintenance apparatus which concerns on the modification 1 is shown. The structure of the semiconductor device which concerns on the modification 2 is shown.

  Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention.

  FIG. 1 shows a configuration of a semiconductor device 100 according to the present embodiment. The semiconductor device 100 measures a parameter serving as an index of the characteristic variation of the semiconductor element, predicts the lifetime of the semiconductor element based on the result, and controls the characteristic variation to protect the semiconductor element or exhaust the target lifetime. The purpose is to adjust. The semiconductor device 100 includes a semiconductor element 10, an adjustment unit 12, a measurement unit 20, and a prediction unit 30.

  The semiconductor element 10 and other components include a switching terminal 19G for inputting a switching signal from the outside, a drain terminal 19D and a source terminal 19S for energizing current, and an output terminal for outputting a signal to the outside. It is connected between 19O.

  The semiconductor element 10 is a switching element incorporated in the semiconductor device 100 of the present embodiment. As an example, a metal oxide semiconductor field effect transistor (MOSFET) formed on a substrate having a polytype crystal structure such as a SiC substrate or a GaN substrate. ). The semiconductor element 10 is not limited to a MOSFET, but may be an element that can be composed of a compound semiconductor, such as an insulated gate bipolar transistor (IGBT). The semiconductor element 10 includes a gate electrode (also simply referred to as a gate) G, a drain electrode (also simply referred to as a drain) D, and a source electrode (also simply referred to as a source) S. And the source terminal 19S.

  The adjustment unit 12 is a unit that switches and connects resistance elements having different resistance values to the gate G of the semiconductor element 10, and includes a plurality of resistance elements 12R and a plurality of switches 12S.

  The plurality of resistance elements 12 </ b> R are elements having different resistance values within a range of 0.01 to 10Ω, for example, and one end of each of the resistance elements 12 </ b> R is connected to the gate G of the semiconductor element 10.

  The plurality of switches 12S are elements that are controlled to open and close based on a prediction result input from the prediction unit 30 described later, and one end of each is connected to the plurality of resistance elements 12R, and the other end is connected to the switching terminal 19G. Connected.

  Thereby, the plurality of resistance elements 12R are arranged in parallel between the switching terminal 19G and the gate G. The adjustment unit 12 can change the resistance value of the gate resistance by connecting the resistance element 12R having any one of the resistance values as a gate resistance Rg between the switching terminal 19G and the gate G by using the plurality of switches 12S. . Alternatively, the resistance value of the gate resistance may be changed equivalently by combining the single resistance element 12R and the variable pulse current source to change the gate current flowing to the gate G. Here, the gate current is a switching signal input to the switching terminal 19 </ b> G in order to switch the semiconductor element 10. The relationship between the resistance value of the gate resistance and the performance of the semiconductor element 10 and the function performed by the toning unit 12 will be described later.

  The measurement unit 20 is a unit that measures a parameter that is an index of characteristic variation of the semiconductor element 10, and includes a first measurement unit 21 and a second measurement unit 22. Note that the overshoot time of the gate voltage and its total, the threshold voltage and its variation, the on-voltage, the on-resistance, and the like can be selected as parameters.

  The first measurement unit 21 measures the overshoot time of the gate voltage of the semiconductor element 10 and transmits the result to the prediction unit 30 described later. The first measurement unit 21 is connected to the gate G of the semiconductor element 10, detects the gate voltage, and analyzes the transient characteristics thereof to calculate the overshoot time. Furthermore, the first measurement unit 21 measures the cumulative overshoot time corresponding to the switching of the semiconductor element 10 by accumulating the overshoot time within the measurement target period. Here, the measurement target period may be, for example, a period after the semiconductor device 100 is incorporated in an external system and actual operation is started.

  The first measurement unit 21 may further measure the operating time of the semiconductor device 100 and output the result to the prediction unit 30.

  The second measurement unit 22 measures the threshold voltage and the on-voltage of the semiconductor element 10 and transmits the results to the prediction unit 30 described later. The configuration of the second measuring unit 22 and the method for measuring the threshold voltage and the on-voltage of the semiconductor element 10 will be described later.

The prediction unit 30 is a unit that is connected to the measurement unit 20 and predicts the lifetime of the semiconductor element 10 using various parameters related to the semiconductor element 10 to be input. In the present embodiment, the gate voltage overshoot time (and its total), the threshold voltage V _th, and the ON voltage V _ON are used as parameters related to the semiconductor element 10. A method for predicting the lifetime of the semiconductor element 10 will be described later.

  FIG. 2 shows an example of a transient characteristic of the gate voltage input to the gate G of the semiconductor element 10. The gate voltage is a switching signal for controlling the opening and closing of the connection between the drain and the source of the semiconductor element 10, and the gate G of the semiconductor element 10 from the external system incorporating the semiconductor device 100 through the switching terminal 19 </ b> G and the adjustment unit 12. Is input. The gate voltage receives not only the impedance in the semiconductor device 100 but also the impedance in the external system, and changes temporally. As an example, the gate voltage is a turn-off signal that opens a connection between the drain and source of the semiconductor element 10. .

  In the transient characteristics of the gate voltage, the rise or fall slope of the gate voltage, the overshoot or undershoot of the gate voltage (unless otherwise specified, the reference voltage The degree of the overshoot is fluctuated with the intention of accompanying a temporary change. The time when the gate voltage is above or below the reference voltage is called the overshoot time. The reference voltage is a voltage that is uniquely determined from the rated voltage of the semiconductor element 10 and is, for example, −10V.

  The gate voltage exhibits a gradual fall and a short overshoot time (for example, dT1 = 50 to 100 nanoseconds) with respect to a resistance value Rg1 (for example, 6.8Ω) having a large gate resistance. A gradual fall results in a slow switching speed of the semiconductor element 10 and a short overshoot time results in a long lifetime of the semiconductor element 10 as will be described later. However, the gate resistance having a large resistance value causes a decrease in performance (that is, low efficiency) of the semiconductor element 10. On the other hand, the gate voltage exhibits a sharp fall and a long overshoot time (for example, dT2 = 150 to 500 nanoseconds) with respect to a resistance value Rg2 (for example, 4.7Ω) having a small gate resistance. A sudden fall results in a fast switching speed of the semiconductor element 10 and a long overshoot time results in a short lifetime of the semiconductor element 10 as described below. However, performance improvement (that is, high efficiency) of the semiconductor element 10 is achieved by the gate resistance having a small resistance value.

  In addition, although the off signal with an undershoot was demonstrated as gate voltage, it is an on signal which closes the connection between the drain-source of the semiconductor element 10, rises rapidly from an off voltage, exceeds a threshold voltage, and with an overshoot Even at a gate voltage saturated to an on voltage higher than the off voltage, the same behavior as the resistance value of the gate resistance is exhibited, and the performance of the semiconductor element 10 is changed.

  Accordingly, the adjustment unit 12 changes the resistance value of the gate resistance Rg, for example, by changing to a smaller resistance value, the efficiency of the semiconductor element 10 can be improved and the switching speed can be increased, and the resistance value is changed to a larger resistance value. By doing so, the service life of the semiconductor element 10 can be extended, that is, the life can be extended.

  FIG. 3 shows the configuration of the second measurement unit 22. The second measurement unit 22 includes a DESAT diode 22a, a current source 22b, and a comparator 22c.

  The DESAT diode (also simply referred to as a diode) 22a is configured by, for example, a plurality of diodes connected in series, and has a cathode and an anode connected to the drain D of the semiconductor element 10 and the comparator 22c, respectively. The DESAT diode 22a has a drop voltage Vf equal to the sum of the drop voltages of the plurality of diodes connected in series.

The current source 22b is connected to the anode of the diode 22a, and _flows a constant current _Idesat into the drain D of the semiconductor element 10 through the diode 22a.

The comparator 22c compares the anode potential (also referred to as DESAT potential) V _desat of the diode 22a with the reference V _ref and outputs OUT as a result. The DESAT potential V _desat is equal to the sum of the drain voltage V _D of the semiconductor element 10 (corresponding to the drain-source voltage V _DS ) and the drop voltage Vf of the diode 22a.

Therefore, the second measurement unit 22 monitors the output OUT of the comparator 22c while changing the reference V _ref , for example, so that the drain voltage V _D = V _ref −Vf is obtained from the reference V _ref when the output OUT changes. Can be obtained.

The DESAT potential V _desat may be further amplified by another comparator, compared with the reference V _ref by the comparator 22c, and the drain voltage V _D may be obtained from the reference V _ref when the output OUT changes.

The second measuring unit 22 measures the threshold voltage _Vth of the semiconductor element 10 as follows. The second measurement unit 22 applies a voltage of, for example, 20 V (that is, a drain-source voltage V _DS ) between the drain D and the source S of the semiconductor element 10, and has a current of, for example, 18 mA from the current source 22 b through the diode 22 a. A current (that is, a drain current I _D ) is supplied to the drain D of the semiconductor element 10. In this state, the second measuring unit 22, gradually increasing voltage to the gate G of the semiconductor device 10 (i.e., the gate voltage) to measure the drain voltage V _D while applying a. The gate voltage is detected by the first measurement unit 21. In this case, at equal gate voltage to the threshold voltage _{V th,} the drain voltage _{V D} falls. The second measurement unit 22, by detecting the gate voltage while detecting a drop in the drain voltage V _D, to obtain a threshold voltage V _th of the semiconductor device 10.

Incidentally, the second measuring unit 22 or together with place of the threshold voltage V _th, for example, to calculate the variation of the semiconductor device 100 from the initial threshold voltage V _th incorporating an external system, may be output.

The second measuring unit 22 measures the ON voltage V _ON of the semiconductor element 10 as follows. The second measurement unit 22 applies, for example, a voltage of 20 V (ie, gate voltage) to the gate G of the semiconductor element 10, and applies a current of 18 A (ie, drain current I _D ) from the current source 22b via the diode 22a. It flows into the drain D of the semiconductor element 10. In this state, the second measurement unit 22 detects the drain voltage V _D to obtain the on-voltage V _ON of the semiconductor element 10. The on-resistance of the semiconductor element 10 is obtained by dividing the obtained on-voltage V _ON by the drain current _ID .

The conditions for the gate voltage V _G , the drain current I _D , and the drain-source voltage V _DS when measuring the threshold voltage V _th and the on-voltage V _ON of the semiconductor element 10 are as follows when the semiconductor device 100 is in actual operation. Different from them. Therefore, a test period is provided when the external system in which the semiconductor device 100 is incorporated is stopped or during maintenance, and various parameters of the semiconductor element 10 such as the threshold voltage V _th and the ON voltage V _ON are measured within the test period. I decided to.

FIG. 4 shows an example of variation of the threshold voltage _Vth of the semiconductor element 10 with respect to the operation time of the semiconductor device 100. Here, the threshold voltage _Vth is measured for each of a small (eg, 4.7Ω) and large (eg, 6.8Ω) gate resistance Rg. It can be seen that the threshold voltage _Vth increases with the operating time, and the degree of increase is abrupt for a small gate resistance and moderate for a large gate resistance.

SiC, SiC elements formed on a substrate having a polytype crystal structure of GaN and the like, such as GaN devices, by being repeatedly used, stress the gate voltage V _G is element especially above the reference voltage by an overshoot, By accumulating this, the threshold voltage _Vth varies. The increase in the threshold voltage V _th causes, for example, a delay in the ON timing of the semiconductor element 10 and causes a deterioration in the rated performance of the semiconductor device 100.

As described above, a small gate resistance results in a long overshoot time, and a large gate resistance results in a short overshoot time. Therefore, it is expected that the change in the threshold voltage V _th can be scaled by the overshoot time of the gate voltage V _G. Therefore, the threshold voltage V _th, determines the allowable range of the increase, determines the service of semiconductor device 10 by increasing up to the threshold voltage V _th is the allowable range, the prediction unit and the service life (i.e., the life) 30 predicting from the measurement result of the overshoot time of the gate voltage V _G through.

FIG. 5 shows an example of the life prediction and life adjustment of the semiconductor element 10 by the fluctuation of the threshold voltage _Vth by the prediction unit 30. Here, as an example, define the useful limits of the semiconductor element 10 and 5% increase in the threshold voltage V _th, target life design time T ₄ the semiconductor device 10 to an increase in the threshold voltage V _th is expected to reach this limit It is determined. In the figure, referred to the origin, the point indicating the 5% increase in the threshold voltage V _th at design time T _4, the target life curve L0 the one-dot chain line connecting. Incidentally, design time _{T 4,} for example, of the order of 40000 hours or 10,000 hours from an example of a change of a threshold voltage _{V th} shown in Fig.

Prediction unit 30 first from the measurement unit 20, receives the measurement result of the operating time of the measurement results and the semiconductor device 100 of the overshoot time of the gate voltage V _G. Note that the prediction unit 30 may periodically receive these measurement results when the semiconductor device 100 is in operation, or may appropriately receive the measurement results when the semiconductor device 100 is not in operation. Next, the predicting unit 30 predicts the fluctuation of the threshold voltage _Vth from the received measurement result of the accumulated overshoot time using the interphase relationship. The interphase relationship between the accumulated overshoot time t and the fluctuation of the threshold voltage _Vth can be obtained in advance by using, for example, a test semiconductor device 100, for example, ΔV _th = a + bt using a linear function. And can be given. Next, the prediction unit 30 compares the predicted variation in the threshold voltage _Vth with the target life curve L0.

For example, as shown by using points P1 to P3 in FIG. 5, when the predicted variation of the threshold voltage _Vth is located on or near the target life curve L0, the prediction unit 30 determines the life τ of the semiconductor element 10. ₀ is predicted to be equal to or approximately equal to the target life T ₄ , and this prediction result is transmitted to the adjustment unit 12. Finally, the adjustment unit 12 determines that the semiconductor device 100 is used according to the rating from the received life prediction result, and maintains the current resistance value of the gate resistance Rg.

Further, for example, as shown by using the point P4 in FIG. 5, when the predicted variation in the threshold voltage _Vth is higher than the target life curve L0, the prediction unit 30 sets the life τ ₁ of the semiconductor element 10 as the target. The service life is evaluated as being shorter than the life T ₄ , the service life τ ₁ is specifically predicted from the predicted deviation from the target life curve L 0, and the prediction result is transmitted to the adjustment unit 12. Finally, the adjustment unit 12 determines that the semiconductor device 100 is being used under conditions stricter than the rating based on the received prediction result of the lifetime, and changes the resistance value of the gate resistance Rg to a large value. Thereby adjusting the rate of change of the gate voltage V _G, i.e. by shortening the overshoot time, it is possible to prolong the semiconductor device 10 by suppressing the fluctuation of the threshold voltage. Note that the gate resistance may be changed to an appropriate resistance value by the adjustment unit 12 so that the remaining life becomes substantially equal to the difference between the target life T ₄ and the current operating time T ₁ .

  Note that the prediction unit 30 determines that the predicted lifetime of the semiconductor element 10 is approximately equal to or exceeds the target lifetime, or the measurement result of the accumulated overshoot time received from the measurement unit 20 corresponds to the target lifetime. If the parameter related to the semiconductor element 10 reaches the alert level, an alert signal may be output from the output terminal 19O to an external system or the like. At this time, the adjustment unit 12 may continue to operate the semiconductor device 100 by giving priority to high-speed switching and high efficiency without changing the resistance value of the gate resistance in accordance with the lifetime prediction by the prediction unit 30 due to external setting or the like. Good.

In addition, for example, as shown with reference to FIG. 5 two points P5, if the variation of the predicted threshold voltage V _th is at a low target life curve L0 position, the prediction unit 30, the target lifetime tau ₂ of the semiconductor element 10 The service life is evaluated to be longer than the service life T ₄ , and the service life τ ₂ is specifically predicted based on the deviation of the predicted fluctuation from the target service life curve L 0, and the prediction result is transmitted to the adjustment unit 12. Finally, the adjustment unit 12 determines that the semiconductor device 100 is used under a condition looser than the rating based on the received prediction result of the lifetime, and changes the resistance value of the gate resistance Rg to a small value. Thus, by shortening the fall time of the gate voltage V _G, it is possible to improve the efficiency with increasing the switching speed. It is noted that the threshold voltage is fluctuated within an allowable range and the life of the semiconductor element 10 is shortened. For example, the remaining life is approximately equal to the difference between the target life T ₄ and the current operating time T _2. The adjustment unit 12 may change the gate resistance to an appropriate resistance value.

  In this way, it is possible to extend the life by suppressing the deterioration of the semiconductor element 10 while drawing out the rated performance such as the switching speed and efficiency of the semiconductor element 10 as much as possible.

The prediction unit 30 measures the threshold voltage _Vth of the semiconductor element 10 by the measurement unit 20 when the semiconductor device 100 is not in operation, and directly predicts the lifetime of the semiconductor element 10 using the result. You may adjust a lifetime based on it. Details of life prediction and life adjustment are as described above.

Further, the prediction unit 30 measures the on-voltage V _ON of the semiconductor element 10 by the measurement unit 20 when the semiconductor device 100 is not in operation, and if the result exceeds the allowable range, the parameter related to the semiconductor element 10 is set to the alert level. If the alert signal has been reached, an alert signal may be output from the output terminal 19O.

FIG. 6 shows an example of the variation of the _ON voltage V _ON of the semiconductor element 10 with respect to the operating time of the semiconductor device 100. It has been empirically known that the _ON voltage V _ON increases when a defect is generated inside the semiconductor element 10 due to light generated by energization of the body diode of the semiconductor element 10. The body diode is a diode formed parasitically on the inside of the structure of the semiconductor element. This is because if a current continues to flow through the body diode, stacking faults grow on the SiC wafer, the SiC epitaxial layer, or both starting from the basal plane dislocation. The on-voltage V _ON increases discontinuously with the operating time. Specifically, after the actual operation of the semiconductor device 100 is started, the operating time is increased by about 1% in about 1 (arbitrary unit), further increased by about 5% during the operating time 5 to 10, and between the operating times 10 and 35. Approximately constant and increases by about 10% during the operating time 35-40. An increase in on-resistance V _ON results in an increase in loss. Therefore, an allowable range is determined for the ON voltage V _ON , and an alert signal is output by the prediction unit 30 when the measurement result exceeds this range.

  The semiconductor device 100 may be connected to a monitoring device via the network 220, and the characteristic variation of the semiconductor element 10 may be monitored by the monitoring device.

  FIG. 7 shows a configuration of a maintenance device 200 that remotely monitors a plurality of semiconductor devices 100. The maintenance device 200 includes a plurality of semiconductor devices 100 and a monitoring device 210 according to the present embodiment. The plurality of semiconductor devices 100 and the monitoring device 210 are connected to the network 220 so that they can communicate with each other.

  The plurality of semiconductor devices 100 are respectively incorporated in a plurality of external systems (not shown). The plurality of semiconductor devices 100 are connected to the network 220 via the output terminal 19 </ b> O, and transmit, to the monitoring device 210, the results of lifetime prediction by the prediction unit 30, the measurement results of parameters that serve as indicators of characteristic fluctuations by the measurement unit 20 .

  The monitoring device 210 is an information processing device including a computer, a microcontroller, and the like, and exhibits a monitoring function by executing a monitoring program, for example. The monitoring device 210 receives, as a result of life prediction of the semiconductor element 10 from a plurality of semiconductor devices 100, measurement results of parameters that serve as indicators of characteristic fluctuations, etc., and collectively displays them on the monitor.

  Note that the monitoring device 210 has a resistance value of the gate resistance Rg for adjusting the lifetime based on a result of the lifetime prediction of the semiconductor element 10 received from the plurality of semiconductor devices 100, a measurement result of a parameter serving as an index of characteristic variation, and the like. May be generated and transmitted to a plurality of semiconductor devices 100. In the plurality of semiconductor devices 100, the adjustment unit 12 changes the resistance value of the gate resistance in accordance with the setting signal received from the monitoring device 210.

  Note that a semiconductor incorporating a measurement unit 20 that measures a parameter that is an index of characteristic variation of the semiconductor element 10 and a prediction unit 30 that predicts the lifetime of the semiconductor element 10 using measurement results of various parameters by the measurement unit 20. A maintenance device configured independently of the device 100 may be used to measure parameters of the semiconductor element 10 included in the semiconductor device 100, predict the lifetime of the semiconductor element based on the result, and control the characteristic variation.

  FIG. 8 shows the configuration of the semiconductor device 110 and the maintenance device 120 according to the first modification. Here, components that are the same as or correspond to the respective components of the semiconductor device 100 described above are denoted by the same reference numerals, and detailed description thereof is omitted.

  The semiconductor device 110 includes a semiconductor element 10 and an adjustment unit 12. The semiconductor element 10 and the adjustment unit 12 output a gate voltage to the outside from a switching terminal 19G for inputting a switching signal from the outside, a drain terminal 19D and a source terminal 19S for supplying a current, and a gate G of the semiconductor element 10. And an input terminal 19I for inputting a setting signal to the adjustment unit 12 from the outside.

  The maintenance device 120 is a device for detachably connecting to the semiconductor device 110 including the semiconductor element 10 and maintaining it, and includes a measurement unit 20, a prediction unit 30, and a setting unit 40.

  The measurement unit 20 is configured in the same manner as that of the semiconductor device 100 described above. However, the 1st measurement part 21 is connected to the output terminal 19O of the semiconductor device 110, and the gate voltage of the semiconductor element 10 is input through this. The second measuring unit 22 is connected to the drain terminal 19D of the semiconductor device 110, and the drain voltage of the semiconductor element 10 is input through the second measuring unit 22.

  The prediction unit 30 is configured in the same manner as that of the semiconductor device 100 described above. However, the prediction result of the lifetime of the semiconductor element 10 is output to the setting unit 40.

  The setting unit 40 changes the set value of the change rate of the gate voltage of the semiconductor element 10 when the life predicted by the prediction unit 30 is shorter than the target life. Here, for example, the resistance value of the gate resistance Rg can be used as the set value. The setting unit 40 transmits the changed setting value to the adjustment unit 12 of the semiconductor device 110 via the input terminal 19I. Thereby, the adjustment unit 12 changes the resistance value of the gate resistance Rg to a set value. Here, when the adjustment unit 12 is configured by one resistive element and a variable pulse current source, the current value of the variable pulse current source is changed so as to be the value of the gate resistance Rg which is a set value, and the gate By changing the current, the resistance value of the gate resistance Rg is equivalently changed to the set value.

  Note that the maintenance device 120 may be connected to the semiconductor device 110 via a network.

  FIG. 9 shows a procedure of a maintenance method for the semiconductor device 110 using the maintenance device 120 according to the first modification.

  In step S <b> 1, the measurement unit 20 measures a parameter that is an index of characteristic variation of the semiconductor element 10. As parameters, it is possible to select an overshoot time of the gate voltage and its total, a threshold voltage and its fluctuation, an on voltage, an on resistance, and the like.

  In step S <b> 2, the lifetime of the semiconductor element 10 is predicted by the prediction unit 30 using the parameters measured by the measurement unit 20. For example, the prediction unit 30 predicts the lifetime of the semiconductor element 10 from the accumulated gate voltage overshoot time. The details of the life prediction are as described above.

  In step S <b> 3, the setting unit 40 changes the set value of the change rate of the gate voltage of the semiconductor element 10. When the lifetime of the semiconductor element 10 predicted by the prediction unit 30 is shorter than the preset target lifetime, the setting unit 40 changes the resistance value of the gate resistance Rg to a large value as the setting value. Thereby, the gate resistance Rg is changed to a large set value by the adjustment unit 12, the overshoot time is shortened, and the fluctuation of the threshold voltage is suppressed, thereby extending the life of the semiconductor element 10.

Note that the setting unit 40 may change the resistance value of the gate resistance Rg as a setting value so that the life of the semiconductor element 10 is almost the target life. Further, when the lifetime of the semiconductor element 10 predicted by the prediction unit 30 is longer than a preset target lifetime, the resistance value of the gate resistance Rg as a set value may be changed to a small value. Thus, changes to the gate resistor Rg is lower the set value by the adjustment unit 12, the fall time of the gate voltage V _G is reduced, efficiency is improved with increased switching speed. Alternatively, the resistance value of the gate resistance Rg may be equivalently changed to a small set value by changing the current value of the variable pulse current source to a small value and reducing the gate current.

  Note that the semiconductor device 100 of this embodiment can be incorporated into an external system that is a power device such as a power conditioner (PCS), an inverter, or a smart grid.

  FIG. 10 shows a circuit configuration of the semiconductor device 111 according to the second modification. Similar to the semiconductor device 100, the semiconductor device 111 includes the semiconductor element 10, the adjustment unit 12, the measurement unit 20, and the prediction unit 30. Since the basic configuration of the semiconductor device 111 is the same as that of the semiconductor device 100 described above, detailed description of the same or corresponding configuration as the semiconductor device 100 is omitted.

  The adjustment unit 12 is a unit that equivalently changes the resistance value of the resistance element connected to the gate G of the semiconductor element 10 by adjusting the gate current flowing therethrough, and includes one resistance element 12R and two variable elements. It has pulse current sources 12T and 12U.

  The resistance element 12 </ b> R is an element having a resistance value within a range of 0.01 to 10Ω, for example, and one end is connected to the gate G of the semiconductor element 10.

  The variable pulse current sources 12T and 12U are units that are controlled by a prediction result input from the prediction unit 30 and energize a predetermined gate current. One end of the variable pulse current source 12T is connected to the high potential side VH, and the other end is connected to the switching terminal 19G. One end of the variable pulse current source 12U is connected to the switching terminal 19G, and the other end is connected to the source terminal 19S. Thereby, the variable pulse current sources 12T and 12U are arranged in parallel between the high potential side VH and the source terminal 19S (that is, the low potential side VL) with the switching terminal 19G interposed therebetween.

  The adjustment unit 12 can change the resistance value of the gate resistance equivalently by energizing the resistance element 12R with a predetermined gate current by the variable pulse current source 12T or 12U or in the opposite direction. The relationship between the resistance value of the gate resistance and the performance of the semiconductor element 10 and the function performed by the toning unit 12 are the same as those described above.

  When the switching element is turned on, the gate voltage changes from the turn-off voltage to the turn-on voltage. At this time, if a pulse current is applied to the variable pulse current source 12U, the current flowing into the gate G is reduced only during the energization period of the variable pulse current source 12U, so that the gate resistance is equivalently increased. When the switching element is turned off, the pulse current is supplied to the variable pulse current source 12T, so that the current drawn from the gate G is reduced only during the conduction period, so that the gate resistance is equivalently increased. Although the operation for increasing the gate resistance equivalently has been described here, the operation for reducing the gate resistance equivalently can be realized by reversing the variable pulse current source to be operated.

  Note that the resistor 12R may be omitted, and the adjustment unit 12 may be configured with only the variable pulse current sources 12T and 12U.

  Therefore, also in the modified example 2, the adjustment unit 12 changes the resistance value of the gate resistance equivalently. For example, the efficiency of the semiconductor element 10 can be improved and the switching speed can be increased by increasing the gate current flowing through the gate resistance and changing it to a smaller resistance value equivalently. Further, by changing to a smaller current value and to a larger resistance value, the service life of the semiconductor element 10 can be extended, that is, the life can be extended.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

  The order of execution of each process such as operations, procedures, steps, and stages in the apparatus, system, program, and method shown in the claims, the description, and the drawings is particularly “before” or “prior to”. It should be noted that the output can be realized in any order unless the output of the previous process is used in the subsequent process. Regarding the operation flow in the claims, the description, and the drawings, even if it is described using “first”, “next”, etc. for convenience, it means that it is essential to carry out in this order. It is not a thing.

  DESCRIPTION OF SYMBOLS 10 ... Semiconductor element, 12 ... Adjustment part, 12R ... Resistance element, 12S ... Switch, 12T, 12U ... Variable pulse current source, 19D ... Drain terminal, 19G ... Switching terminal, 19I ... Input terminal, 19O ... Output terminal, 19S ... Source terminal 20 ... Measurement unit 21 ... First measurement unit 22 ... Second measurement unit 22a ... DESAT diode (diode) 22b ... Current source 22c ... Comparator 30 ... Prediction unit 40 ... Setting unit DESCRIPTION OF SYMBOLS 100,110,111 ... Semiconductor device, 120 ... Maintenance apparatus, 200 ... Maintenance apparatus, 210 ... Monitoring apparatus, 220 ... Network.

Claims (19)

A semiconductor element formed on a substrate having a polytype crystal structure;
A measurement unit for measuring a parameter including an overshoot time of the gate voltage of the semiconductor element;
A semiconductor device comprising:   The semiconductor device according to claim 1, wherein the substrate is a SiC substrate or a GaN substrate.   The semiconductor device according to claim 1, wherein the measurement unit measures a cumulative overshoot time according to switching of the semiconductor element within a measurement target period.   The semiconductor device according to claim 1, wherein the measurement unit measures a variation in a threshold voltage of the semiconductor element as at least one of the parameters.   The semiconductor device according to claim 1, wherein the measurement unit measures at least one of an on-voltage and an on-resistance of the semiconductor element as at least one of the parameters.   The semiconductor device according to claim 1, wherein the measurement unit measures the parameter during a test period of the semiconductor device.   The semiconductor device according to claim 1, further comprising a prediction unit that predicts a lifetime of the semiconductor element using the parameter.   The semiconductor device according to claim 7, wherein the prediction unit predicts a period until the parameter is out of an allowable range.   9. The semiconductor device according to claim 7, further comprising: an adjustment unit that adjusts a change rate of a gate voltage of the semiconductor element when the life predicted by the prediction unit is shorter than a target life.   The semiconductor device according to claim 9, wherein the adjustment unit changes a resistance value of a gate resistor connected between a switching terminal for inputting a switching signal from the outside and a gate of the semiconductor element, or a gate current value by a variable pulse current source. apparatus.   The semiconductor device according to claim 7, wherein the prediction unit outputs an alert signal in response to the parameter reaching an alert level. A semiconductor device according to any one of claims 1 to 11,
A monitoring device connected to the semiconductor device via a network;
A maintenance device comprising: A maintenance device for maintaining a semiconductor device including a semiconductor element,
A measurement unit that measures a parameter that is an index of characteristic variation of the semiconductor element;
A maintenance device comprising: a prediction unit that predicts the lifetime of the semiconductor element using the measured parameter.   The maintenance device according to claim 13, further comprising a setting unit that changes a set value of a change rate of a gate voltage of the semiconductor element in the semiconductor device when the life predicted by the prediction unit is shorter than a target life. .   The setting unit is configured to determine a resistance value of a gate resistor connected between a switching terminal to which the semiconductor device inputs a switching signal from the outside and a gate of the semiconductor element, or a gate current value by a variable pulse current source. The maintenance device according to claim 14, wherein the maintenance device is changed.   The maintenance device according to claim 13, wherein the maintenance device is connected to the semiconductor device via a network. A maintenance method for a semiconductor device including a semiconductor element,
A measurement step of measuring a parameter serving as an index of characteristic variation of the semiconductor element;
A prediction step of predicting the lifetime of the semiconductor element using the measured parameter.   18. The maintenance method according to claim 17, further comprising a setting step of changing a setting value of a change rate of a gate voltage of the semiconductor element in the semiconductor device when a lifetime predicted in the prediction step is shorter than a target lifetime. .   In the setting step, the setting value for determining a resistance value of a gate resistor connected between a switching terminal to which the semiconductor device inputs a switching signal from the outside and a gate of the semiconductor element, or a gate current value by a variable pulse current source is set. The maintenance method according to claim 18 to be changed.

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