JP2012229971A - Semiconductor inspection device and semiconductor inspection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely inspect a dynamic characteristic of a power semiconductor element and a saturation voltage as a static characteristic thereof in one device.SOLUTION: A semiconductor inspection device 1 inspects an electrical dynamic characteristic by switch-operating a switching element 6 being a power semiconductor element and includes a transistor 53 electrically cutting off the switching element 6 following the occurrence of a short circuit current during inspection. In the semiconductor inspection device 1, a constant current circuit 60 is configured for causing the transistor 53 to output a constant current to apply the constant current to the switching element 6 for inspection of a saturation voltage Vce(sat).

Description

  The present invention relates to a semiconductor inspection apparatus and a semiconductor inspection method for inspecting a power semiconductor element.

  In the manufacturing process of a power module for controlling a large current, it is common to inspect electrical characteristics of the power module or a power semiconductor element constituting the power module before the power module is completed. It is. As the inspection items for the electrical characteristics, there are a dynamic characteristic inspection for performing a switching test by applying a large current to the power semiconductor element and a static characteristic inspection for performing a saturation voltage measurement.

In the conventional power module manufacturing process, separate inspection apparatuses are prepared for each of the dynamic characteristic inspection and the static characteristic inspection, and the inspection is performed using the respective inspection apparatuses. In manufacturing such a power module, a production line in which a plurality of inspection devices are arranged for each inspection item is required. By enabling parallel inspection, the inspection time is shortened and the throughput is improved. When trying to plan, it is necessary to install more inspection apparatuses. For this reason, there has been a problem that the inspection apparatus and a transport apparatus that transports a device under test (so-called DUT) to be inspected between the apparatuses are required, and the cost increases.
Therefore, conventionally, various loads such as inductive load, resistance load, capacitive load, passive load, and active load required for inspection items such as switching test and thermal resistance test of power semiconductor elements are provided in one inspection device. A technique is disclosed in which individually prepared inspection apparatuses are integrated into one (see, for example, Patent Document 1).

JP 2010-107432 A

By the way, in the technique disclosed in Patent Document 1, when inspecting a power semiconductor element with a saturation voltage that is a static characteristic when inspecting a dynamic characteristic of the power semiconductor element, the saturation voltage is calculated based on an energization current applied to the power semiconductor element through an inductive load. Will be inspected.
However, at the time of dynamic characteristic inspection, since the energization current changes according to the inductive load and the energization time, it is difficult to measure the saturation voltage with high accuracy.
Therefore, for example, a configuration may be considered in which a constant current power source for making the energization current constant is separately provided in the inspection device, and the saturation voltage is inspected by supplying the current of the constant current power source to the power semiconductor element. There is a problem of increasing the cost.

  The present invention has been made in view of the above-described circumstances, and a semiconductor inspection apparatus capable of precisely inspecting a dynamic characteristic of a power semiconductor element and a saturation voltage as a static characteristic with a single apparatus, and a semiconductor inspection It aims to provide a method.

  To achieve the above object, the present invention provides a power supply circuit for supplying a current to the power semiconductor element to be inspected in a semiconductor inspection apparatus for inspecting electrical dynamic characteristics by switching the power semiconductor element. A measuring unit for supplying a control signal to the power semiconductor element and measuring electrical characteristics; a current detector for detecting a current supplied to the power semiconductor element; and the power semiconductor based on the current detected by the current detector. And an electric control circuit having a function of cutting off a current supplied to the element and a function of supplying a constant current over a predetermined time.

  According to the present invention, an electric control circuit that supplies a constant current for a predetermined time is provided. By supplying a constant current with this circuit, one unit of saturation voltage, which is a dynamic characteristic and a static characteristic of a power semiconductor element, is provided. It can be inspected precisely with this equipment.

  According to the present invention, in the semiconductor inspection apparatus, the electrical control circuit supplies a constant current for a time equal to or longer than a detection time of the measurement unit that measures the electrical characteristics.

  According to the present invention, a constant current can be supplied for a sufficient time required for measurement by the measurement unit.

  In the semiconductor inspection apparatus according to the present invention, the electrical control circuit detects a short-circuit current at the time of measurement by the measurement unit with the current detector, and supplies a cutoff signal to the transistor to cut off the current. The constant current is supplied to the power semiconductor element so that a saturation voltage can be inspected.

  According to the present invention, the constant voltage output operation of the transistor that shuts off the power semiconductor element at the time of occurrence of a short-circuit current is performed, so that the saturation voltage can be inspected by applying the constant current output by the transistor to the power semiconductor element. A constant current can be applied to the power semiconductor element without separately installing a constant current circuit in the apparatus, and dynamic characteristics and saturation voltage can be precisely inspected with a single apparatus.

  According to the present invention, the semiconductor inspection apparatus further includes a changeover switch for turning on / off the supply of a constant current in the transistor according to the inspection of the dynamic characteristics and the saturation voltage.

  According to the present invention, the dynamic characteristics and the saturation voltage can be easily switched by simply operating the changeover switch, and these can be continuously inspected. Therefore, the tact time in the inspection process is shortened and the throughput is improved. Is planned.

  In order to achieve the above object, the present invention performs a switching operation of a power semiconductor element to inspect electrical dynamic characteristics, and electrically connects the power semiconductor element with the occurrence of a short-circuit current in the power semiconductor element. In a semiconductor inspection method using a semiconductor inspection apparatus provided with a transistor that automatically shuts off, the constant current circuit configured to operate the transistor with a constant current output operation causes the transistor to perform a constant current output operation, and the constant current is A saturation voltage is inspected by applying the power semiconductor element.

  According to the present invention, as in the above-described semiconductor inspection apparatus, a constant current can be supplied by a transistor without separately installing a constant current circuit in the apparatus, and dynamic characteristics and saturation voltage can be precisely controlled by a single apparatus. Can be inspected.

According to the present invention, an electric control circuit that supplies a constant current for a predetermined time is provided. By supplying a constant current with this circuit, one unit of saturation voltage, which is a dynamic characteristic and a static characteristic of a power semiconductor element, is provided. It can be inspected precisely with this equipment.
In the present invention, the electrical control circuit includes a configuration for supplying a constant current for a time equal to or longer than a detection time of the measurement unit for measuring the electrical characteristics, so that the measurement unit has sufficient time for measurement. A constant current can be supplied.
In the present invention, the electrical control circuit detects a short-circuit current at the time of measurement by the measurement unit with the current detector, provides a cutoff signal to the transistor to cut off the current, and the transistor supplies the constant current to the power. By supplying to the semiconductor element and making it possible to inspect the saturation voltage, a constant current can be applied to the power semiconductor element without separately installing a constant current circuit in the apparatus, and dynamic characteristics and saturation voltage can be obtained with a single device. It can be inspected precisely.
Further, in the present invention, according to the dynamic characteristics and the saturation voltage inspection, by providing a changeover switch for turning on / off the supply of constant current in the transistor, just by operating the changeover switch, Since the inspection of the dynamic characteristics and the saturation voltage can be easily switched and these can be continuously inspected, the tact time in the inspection process can be shortened and the throughput can be improved.

It is a circuit diagram which shows the electrical structure of the test | inspection apparatus which concerns on embodiment of this invention. It is explanatory drawing of the time waveform change of the collector current and collector-emitter voltage at the time of the switching characteristic test | inspection which is a dynamic characteristic, (A) shows a time waveform, (B) expanded the one part period of (A). FIG. It is a figure which shows an example of the static characteristic of a transistor. It is a figure which shows the test | inspection flow of a semiconductor test | inspection apparatus.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, an arm of an inverter device that is a power conversion device that converts direct current to alternating current is illustrated as a power module, and a semiconductor inspection device that inspects the arm as a device under test (so-called DUT) will be described.

FIG. 1 is a circuit diagram showing an electrical configuration of the semiconductor inspection apparatus 1.
The semiconductor inspection apparatus 1 is an apparatus that inspects an arm 2 for one phase included in an inverter device. The arm 2 is configured by connecting in series two switching elements 6 each having a diode 4 connected in reverse parallel, and the potential is on the high voltage side (“P side”) line and the low voltage side (“N side”). The output is obtained from the midpoint P of the arm 2. The switching element 6 is an IGBT as an example of a power semiconductor element. The arm 2 is inspected in a bare chip state before being incorporated into the inverter module, and each of the switching elements 6 is provided with a gate drive circuit GD that is driven by applying a gate voltage as a control signal to the gate terminal, and a collector-emitter voltage Vce. A voltage measuring device 8 is connected to measure the voltage. The measurement unit 3 that includes the gate drive circuit GD and the voltage measuring device 8 and that measures the electrical characteristics by supplying a control signal to the switching element 6 that is a power semiconductor element is configured.

  This semiconductor inspection apparatus 1 is configured to be able to evaluate an output when each switching element 6 of the arm 2 is switched in accordance with an actual operation state by the gate drive circuit GD, and has a DC power supply 12. A power supply circuit 14; a P-side bus line 16 connected to the high-voltage side of the power supply circuit 14; an N-side bus line 18 connected to the low-voltage side; and a load circuit 19; The arm 2 is electrically connected to the N-side bus line 18.

The power supply circuit 14 includes a discharge circuit 28 having an electrolytic capacitor 20, a backflow prevention diode 22, and a switching element 24. The DC power supply 12 accumulates charges in the electrolytic capacitor 20 and outputs a large current.
The load circuit 19 includes a pseudo-inductive load 31 and a changeover switch 32 for switching the direction of the current flowing through the pseudo-inductive load 31, and simulates a load of an AC motor (for example, a vehicle drive motor of an electric vehicle) driven by the inverter device. Reappear. The middle point P of the arm 2 is connected to the load circuit 19, and a performance test when the arm 2 drives the load circuit 19 is performed as a switching characteristic test (inspection of dynamic characteristics).
A snubber circuit 48 having a snubber capacitor 46 and a resistor 47 is provided between the load circuit 19 and the arm 2.

In addition, the semiconductor inspection apparatus 1 includes a short-circuit protection circuit 50 for protecting the semiconductor inspection apparatus 1 from a short-circuit current generated when the switching element 6 constituting the arm 2 is short-circuit broken through inspection.
The short-circuit protection circuit 50 includes a current transformer 51 as a current detector that detects a current supplied to the switching element 6 through the P-side bus line 16, and a diode 52 connected in reverse parallel. When a short circuit current is detected based on the inserted transistor 53 as a semiconductor switch and the current transformer 51, the gate drive circuit GD of the transistor 53 is controlled to turn off the transistor 53, and from the P-side bus line 16 to the arm 2 And a short-circuit protection control unit 54 for electrically disconnecting. In the present embodiment, an IGBT is used for the transistor 53 because it is necessary to switch off a large current at a high speed.

By the way, when trying to measure the saturation voltage Vce () sat of the collector-emitter voltage Vce of the switching element 6 using the semiconductor inspection apparatus 1 as a static characteristic, the simplest is to the arm 2 at the time of the inspection of the switching characteristic. It is conceivable to measure the saturation voltage Vce (sat) for the switching element 6 on the N side of the arm 2 by using the energization.
However, in this case, since the energizing current is supplied to the switching element 6 on the N side from the pseudo-inductive load 31 that is a load coil through the middle point P of the arm 2, the energizing current is changed according to the energizing time. As a result, the collector current Ic flowing through the switching element 6 on the N side also changes.

2A and 2B are explanatory diagrams of changes in the time waveform of the collector current Ic and the collector-emitter voltage Vce during the inspection of the switching characteristics as dynamic characteristics. FIG. 2A shows the time waveform, and FIG. It is a figure which expands and shows a part of 2 (A) period.
When measuring the saturation voltage Vce (sat) using the collector current Ic, the collector-emitter voltage Vce with respect to the collector current Ic is measured in the period T during which the collector current Ic flows.
However, when the switching characteristic is inspected, the polarity at both ends of the pseudo inductive load 31 is alternately changed. Therefore, the current flowing through the pseudo inductive load 31 is changed, so that the collector current Ic is as shown in FIG. And the collector-emitter voltage Vce also changes accordingly. Therefore, if a time difference Δt occurs in the measurement timing of the collector current Ic, as shown in FIG. 2B, a current difference ΔIc also occurs in the collector current Ic. Vce also changes. Therefore, if the detection timing of the collector current Ic and the detection timing of the collector-emitter voltage Vce are not accurately synchronized, an error occurs in the collector-emitter voltage Vce due to a time difference Δt that is a deviation of the detection timing. As a result, accurate measurement is impossible.
Further, since the saturation voltage Vce (sat) needs to be measured in a linear region, it is necessary to apply and measure a large current (for example, 100 A) to the switching element 6. Since it changes, it is difficult to measure at the timing when such a large current flows, and it is difficult to obtain measurement accuracy.

Therefore, for example, if a constant current circuit for supplying a constant energizing current to the switching element 6 is not provided through the pseudo-inductive load 31 but a constant current circuit is separately provided, the collector current Ic is maintained constant. Therefore, an error occurring in the collector-emitter voltage Vce can be prevented.
However, since the constant current circuit is separately provided, the semiconductor inspection apparatus 1 becomes complicated and expensive.

Therefore, in the present embodiment, as shown in FIG. 1, the constant current circuit 60 is configured by using the transistor 53 provided in the short-circuit protection circuit 50.
More specifically, as shown in FIG. 3, the transistor 53 represented by the IGBT has a constant current characteristic that operates to output a constant current in the active region, and the current value (collector current) at this time is Depends on the gate voltage Vge. Therefore, by applying a predetermined gate voltage Vge through the gate drive circuit GD connected to the gate terminal of the transistor 53, a constant current having a current value required for static characteristic inspection can be output from the transistor 53.

  The constant current circuit 60 constitutes a circuit that causes the transistor 53 included in the short circuit protection circuit 50 to operate at a constant current and outputs a constant current together with the transistor 53. A gate drive circuit GD is connected to the gate terminal of the transistor 53. And a current set value output circuit 62 for setting the current value of the output current Io of the transistor 53. When the static characteristics are inspected, the constant current circuit 60 causes the transistor 53 to operate at a constant current, so that an output current Io having a constant current value based on the setting of the current set value output circuit 62 is output from the emitter terminal of the transistor 53. .

Note that the short-circuit protection control unit 54 is connected to the gate terminal of the transistor 53 and functions as the short-circuit protection circuit 50 while the transistor 53 is operating at a constant current. That is, even when the transistor 53 is operating at a constant current, if a short-circuit current occurs for some reason, the short-circuit protection control unit 54 turns off the transistor 53 and electrically disconnects the arm 2. And cut.
The short circuit protection circuit 50 and the constant current circuit 60 are included, and the function of cutting off the current supplied to the switching element 6 based on the current detected by the current transformer 51 and the current value variable over a predetermined time. An electric control circuit 80 having a function of supplying a constant current is configured.

  The constant current circuit 60 will be described in more detail. The current set value output circuit 62 inputs the set voltage Vi that defines the current value of the output current Io of the transistor 53 to the non-inverting input (+) of the operational amplifier 61. The inverting input (−) of the operational amplifier 61 is connected to the emitter terminal of the transistor 53 via the changeover switch 63. The arm 2 is connected to the changeover switch 63, and a resistor 64 is provided between the changeover switch 63 and the arm 2. The non-inverting input (+) of the operational amplifier 61 is connected to the output side of the resistor 64. When the change-over switch 63 is turned on and closed, the potential difference between the non-inverting input (+) and the inverting input (−). ΔV is expressed by the following equation.

  Potential difference ΔV = set voltage Vi− (resistance value R1 of resistor 64 × output current Io)

  The operational amplifier 61 applies the gate voltage Vge to the gate terminal of the transistor 53 through the gate drive circuit GD so as to set the potential difference ΔV to “zero”. As a result, the output current Io = (set voltage Vi / resistance value R1). A constant output current Io defined by is output.

On the other hand, the P-side bus line 16 is provided with a switch 70 that is turned on / off exclusively with the changeover switch 63 to connect / disconnect the power supply circuit 14 and the arm 2. The changeover switch 63 and the switch 70 are switched on / off depending on which of the dynamic characteristic inspection and the saturation voltage inspection is performed.
That is, at the time of dynamic characteristic inspection, the changeover switch 63 is turned off to stop the operation of the constant current circuit 60, and the switch 70 is turned on, so that the power of the power supply circuit 14 is supplied to the load circuit 19 and the arm 2 and switched. A property check is performed. On the other hand, during the saturation voltage test, the switch 70 is turned off to disconnect the power supply circuit 14 from the load circuit 19 and the arm 2, while the changeover switch 63 is turned on to operate the constant current circuit 60 and the constant current circuit 60 is turned on. The constant current output current Io is supplied from the transistor 53 to the arm 2.

FIG. 4 is a diagram showing an inspection flow of the semiconductor inspection apparatus 1.
When the arm 2 is inspected, first, in order to inspect the switching characteristics as dynamic characteristics, the semiconductor inspection apparatus 1 turns on the switch 70 and connects the power supply circuit 14 to the load circuit 19 and the arm 2, while setting the changeover switch 63. In the state where the constant current circuit 60 is turned off and the power supply circuit 14 is cut off, the arm 2 (switching element 6) is energized from the energization (step S1), and the switching characteristics are measured (step S2).
Next, in order to measure the saturation voltage as a static characteristic, the semiconductor inspection apparatus 1 turns off the switch 70 and turns on the changeover switch 63 to connect the constant current circuit 60 to the arm 2 (step S3). Then, the semiconductor inspection apparatus 1 outputs a constant output current Io based on the setting of the current set value output circuit 62 from the transistor 53 and applies it to the switching element 6 of the arm 2 (step S4), and the saturation voltage Vce (sat ) Is measured (step S5).
In this inspection flow, it is needless to say that the switching characteristics may be inspected after inspecting the saturation voltage Vce (sat).

  Thus, according to this embodiment, when a short-circuit current is generated due to a short-circuit breakdown or the like of the switching element 6 that is a power semiconductor element to be inspected, the transistor provided in the short-circuit protection circuit 50 that electrically cuts off the switching element 6 A constant current circuit 60 for causing 53 to output current at constant current is configured, and a constant current output from the transistor 53 is applied to the switching element 6 by the constant current circuit 60 to check the saturation voltage Vce (sat). Thus, a constant current can be applied to the switching element 6 without separately installing a constant current circuit in the device, and the dynamic characteristics and the saturation voltage Vce (sat) can be precisely inspected with one device. In addition, the semiconductor inspection apparatus 1 itself can be prevented from increasing in size, complexity, and cost.

  In addition, according to the present embodiment, the changeover switch 63 for turning on / off the constant current operation of the transistor 53 by the constant current circuit 60 according to the inspection of the dynamic characteristics and the saturation voltage Vce (sat) is provided. By simply operating the switch 63, the dynamic characteristics and the saturation voltage can be easily switched, and these can be continuously tested. Thereby, the tact time in the inspection process can be shortened and the throughput can be improved.

The above-described embodiment is merely an aspect of the present invention, and can be arbitrarily modified and applied without departing from the spirit of the present invention.
For example, in the above-described embodiment, the constant current circuit 60 may be any circuit as long as it is a circuit that operates the transistor 53 included in the short circuit protection circuit 50 in the active region and performs a constant current operation that outputs a constant output current Io. Can be adopted.

For example, in the above-described embodiment, the inspection device that inspects the arm 2 of the inverter device is exemplified as the device under test. However, the present invention is not limited thereto, and power semiconductor elements such as IGBTs and MOSFETs, or the power semiconductor elements are used. It can be widely used as an inspection apparatus for a configured module device.
In particular, in the above-described embodiment, the characteristics of the backflow prevention diode 4 juxtaposed to the switching element 6 can be inspected in the same manner as the switching element 6. In this case, since the diode 4 is connected in antiparallel with the switching element 6, means for changing the energization direction to the diode 4 is provided in the semiconductor inspection apparatus 1.

1 Semiconductor Inspection Equipment 2 Arm (Power Module)
3 Measurement unit 6 Switching element (power semiconductor element)
14 Power supply circuit 19 Load circuit 50 Short circuit protection circuit 51 Current transformer (current detector)
53 Transistor 54 Short-Circuit Protection Control Unit 60 Constant Current Circuit 61 Operational Amplifier 62 Current Set Value Output Circuit 63 Changeover Switch 64 Resistance 70 Switch 80 Electric Control Circuit Ic Collector Current Io Output Current (Constant Current)
Vce (sat) Saturation voltage Vge Gate voltage Vi Setting voltage

Claims (5)

In a semiconductor inspection apparatus for inspecting electrical dynamic characteristics by switching a power semiconductor element,
A power supply circuit for supplying a current to the power semiconductor element to be inspected;
A measurement unit that applies a control signal to the power semiconductor element and measures electrical characteristics;
A current detector for detecting a current supplied to the power semiconductor element;
An electric control circuit having a function of cutting off a current supplied to the power semiconductor element based on a current detected by the current detector, and a function of supplying a constant current over a predetermined time;
A semiconductor inspection apparatus comprising:   The semiconductor inspection apparatus according to claim 1, wherein the electrical control circuit supplies a constant current for a time equal to or longer than a detection time of the measurement unit that measures the electrical characteristics. The electrical control circuit detects a short-circuit current at the time of measurement by the measurement unit by the current detector, applies a cutoff signal to the transistor to cut off the current, and supplies the constant current to the power semiconductor element by the transistor. The semiconductor inspection apparatus according to claim 1, wherein the saturation voltage can be inspected.   4. The semiconductor inspection apparatus according to claim 3, further comprising a changeover switch for turning on / off the supply of a constant current in the transistor according to the inspection of the dynamic characteristic and the saturation voltage. A semiconductor inspection apparatus including a transistor that performs a switching operation of a power semiconductor element to inspect electrical dynamic characteristics and electrically shuts off the power semiconductor element when a short-circuit current is generated in the power semiconductor element is used. In the semiconductor inspection method
A semiconductor inspection method comprising: a constant current circuit configured to perform a constant current output operation of the transistor; and a constant current output operation of the transistor; .

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