TESTING METHOD AND MANUFACTURING METHOD

Provided is a testing method for testing a semiconductor device provided with a main element portion including a main transistor portion and a main diode portion, and a sensing transistor portion for current detection, the testing method having: operating an element by causing a diode operation of the sensing transistor portion in the semiconductor device in a chip or wafer state; measuring the element by measuring a voltage-current characteristic showing a relationship between a voltage between main terminals of the sensing transistor portion and a current flowing through the main terminals during the diode operation; and determining the element by determining a defectiveness of the semiconductor device based on the voltage-current characteristic.

BACKGROUND

1. Technical Field

The present invention relates to a testing method and a manufacturing method of a semiconductor device.

2. Related Art

Conventionally, a semiconductor module for accommodating a semiconductor device such as an IGBT (Insulated Gate Bipolar Transistor) is known (for example, refer to Patent Document 1).

Patent Document 1: Japanese Patent Application Publication No. 2021-16246

DESCRIPTION OF EXEMPLARY EMBODIMENTS

One side in a direction parallel to the depth direction of a semiconductor substrate (or a semiconductor device) is herein referred to as an “upper” side, and the other side is referred to as a “lower” side. One of two main surfaces of a substrate, a layer, or another member is referred to as an upper surface, and the other surface is referred to as a lower surface. “Upper” and “lower” directions are not limited to a direction of gravity, or a direction in which a semiconductor device is mounted.

In the present specification, a case where a term such as “same” or “equal” is mentioned may include a case where an error due to a variation in manufacturing or the like is included. The error is, for example, within 10%.

FIG.1illustrates a perspective cross-sectional view describing an outline of a semiconductor device100under test. InFIG.1, a partial perspective cross-sectional view of the semiconductor device100is illustrated. The semiconductor device100is an apparatus where a semiconductor element such as a transistor is formed on a semiconductor substrate10. The semiconductor substrate10is a substrate formed of a semiconductor material such as silicon. The semiconductor device100may be in a state of a wafer with a plurality of chips formed, or may be in a state of a chip cut from a wafer. The semiconductor device100includes an insulating film, electrodes and so on provided on an upper surface21and a lower surface23of the semiconductor substrate10, but inFIG.1, structures other than the semiconductor substrate10are omitted. InFIG.1, the x axis and y axis are two orthogonal axes in the plane parallel to the upper surface21of the semiconductor substrate10. And the axis perpendicular to the upper surface21is the z axis. In the present specification, the direction of the z axis may be referred to as a depth direction.

The semiconductor device100in the present example includes a main element portion150and a sensing transistor portion110. The main element portion150includes a main transistor portion70and a main diode portion80. The main transistor portion70may include, for example, IGBT element, or may include other transistors. The main diode portion80includes a reflux diode provided in anti-parallel with the main transistor portion70. The semiconductor device100in the present example is a so-called reverse conducting IGBT (RC-IGBT).

The sensing transistor portion110is provided to detect a current flowing through the main element portion150. The sensing transistor portion110has a structure similar to that of the main transistor portion70, to which a control signal (for example, a gate voltage) input into the main transistor portion70is similarly input. Note that, in the xy plane, the area occupied by the sensing transistor portion110is smaller than the area occupied by the main transistor portion70. The area of the sensing transistor portion110may be 1% or less, or may be 0.1% or less of the area of the main transistor portion70. The magnitude of the current flowing through the sensing transistor portion110is the magnitude of a current flowing through the main transistor portion70multiplied by the value corresponding to the area ratio described above. Therefore, by measuring the current flowing through the sensing transistor portion110, the magnitude of the current flowing through the main transistor portion70can be estimated.

The semiconductor device100in the present example further includes boundary portions120and a separating portion130. The boundary portions120are provided on end portions of the main transistor portion70, the main diode portion80and the sensing transistor portion110in the xy plane. Also, the separating portion130is arranged between the sensing transistor portion110and the main element portion150in the xy plane.

The semiconductor substrate10has a drift region18of an N− type. The drift region18is provided in each of the main element portion150, the sensing transistor portion110, the separating portion130and the boundary portions120.

On the upper surface21side of the semiconductor substrate10, one or more gate trench portions40and one or more dummy trench portions30are provided. In the present specification, the gate trench portion40and the dummy trench portion30may be referred to as a trench portion. Inside the trench portion, a conductive member such as polysilicon and an insulating film that insulates the conductive member and the semiconductor substrate10are provided. The gate trench portion40is electrically connected to the gate electrode arranged above the upper surface21of the semiconductor substrate10. The gate trench portion40functions as a gate electrode to which a gate voltage is applied. No gate voltage is applied to the dummy trench portion30and it does not function as a gate electrode. The emitter electrode described below may be connected to the dummy trench portion30. Each trench portion is provided in a depth direction from the upper surface21to the drift region18of the semiconductor substrate10.

A plurality of trench portions are arranged in a predetermined interval along a predetermined array direction. In the example ofFIG.1, a plurality of trench portions are arrayed along the direction parallel to the x axis. Also the trench portions extend in a predetermined direction on the upper surface21of the semiconductor substrate10. In the example ofFIG.1, the trench portions extend in the direction parallel to the y axis.

Each of the main transistor portion70and the main diode portion80has a plurality of trench portions. In the main transistor portion70of the present example, one or more gate trench portions40and one or more dummy trench portions30are provided alternately along the array direction. Note that the array of the trench portions in the main transistor portion70is not limited to this. In the main diode portion80of the present example, the plurality of dummy trench portions30are provided along the array direction. The gate trench portion40is not provided in the main diode portion80of the present example.

A mesa portion is provided between the respective trench portions in the array direction. The mesa portion of the present example is provided to extend in the y axis direction along the trench on the upper surface of the semiconductor substrate10. In the mesa portion of the main transistor portion70, emitter regions12of an N+ type and base regions14of a P type are provided in order from the upper surface21side of the semiconductor substrate10. The emitter region12has a doping concentration higher than the drift region18. The drift region18is provided below the base region14.

The emitter region12is exposed from the upper surface21of the semiconductor substrate10, and is provided to be in contact with the trench portion in the xy plane. The base region14is provided below the emitter region12and is provided to be in contact with the trench portion in the xy plane. The emitter region12and the base region14are connected electrically to the emitter electrode provided above the upper surface21of the semiconductor substrate10. The base region14may be connected to the emitter electrode via the contact region15of the P+ type provided on the upper surface21of the semiconductor substrate10. The doping concentration of the contact region15is higher than the doping concentration of the base region14. On the upper surface21of the semiconductor substrate10, the emitter regions12and the contact regions15may be arranged alternately along the y axis direction.

In the mesa portion of the main diode portion80, the base region14of the P type is provided to be in contact with the upper surface21of the semiconductor substrate10. The drift region18is provided below the base region14.

Each trench portion reaches the drift region18penetrating the base region14from the upper surface21of the semiconductor substrate10. In the region with the emitter region12provided, each trench portion may penetrate the emitter region12as well. When the predetermined gate voltage is applied to the gate trench portion40, a channel is formed by the electron inversion layer on the surface layer of the interface that is in contact with the gate trench portion40in the base regions14. A current flows through the channel between the emitter regions12and the drift region18.

In the main transistor portion70, in the region in contact with the lower surface23of the semiconductor substrate10, a collector region22of the P+ type is provided. The doping concentration of the collector region22is higher than the doping concentration of the base region14.

In the main diode portion80, in the region in contact with the lower surface23of the semiconductor substrate10, a cathode region82of the N+ type is provided. The doping concentration of the cathode region82is higher than the doping concentration of the drift region18. The collector region22and the cathode region82are connected to the collector electrode provided on the lower surface23of the semiconductor substrate10. The gate electrode, emitter electrode and collector electrode described above may be formed of a metallic material such as aluminum.

The sensing transistor portion110has a structure similar to the main transistor portion70. Note that, in the sensing transistor portion110, the dummy trench portion30may not be provided. Also above the sensing transistor portion110, the sensing electrode is provided instead of the emitter electrode. The sensing electrode has functions and structures similar to those of the emitter electrode, and is separated from the emitter electrode.

In the boundary portion120, one or more trench portions are provided. The trench portion provided in the boundary portion120may be a dummy trench portion30, or may be a gate trench portion40, or may be both of the dummy trench portion30and the gate trench portion40. In the mesa portion of the boundary portion120in the present example is provided with the contact region15and the base region14. The contact region15is exposed from the upper surface21. The base region14is provided between the contact region15and the drift region18. In the boundary portion120, the collector region22in contact with the lower surface23of the semiconductor substrate10may be provided.

In the separating portion130, a well region11of the P+ type is provided. The well region11has a doping concentration higher than the base region14. Also the well region11is provided from the upper surface21to the position deeper than the trench portion in the semiconductor substrate10. In the separating portion130, the base region14sandwiched between the well regions11in the xy plane may be provided. By providing the separating portion130, the movement of carriers between the sensing transistor portion110and the main element portion150are suppressed.

FIG.2illustrates a circuit diagram describing an outline of the semiconductor module200embedding the semiconductor device100. The semiconductor module200may have a resin case accommodating the semiconductor device100. In the resin case, the wiring pattern, terminal and electrical element that are connected to the semiconductor device100may be accommodated.

As described inFIG.1, the semiconductor device100includes a main transistor portion70, a main diode portion80and a sensing transistor portion110. The main transistor portion70and the main diode portion80are connected in anti-parallel. That is, the emitter of the main transistor portion70is connected to the anode of the main diode portion80, and the collector of the main transistor portion70is connected to the cathode of the main diode portion80. InFIG.2, the emitter electrode of the semiconductor device100is indicated by the terminal E, the collector electrode is indicated by the terminal C, the gate electrode is indicated by the terminal G, and the sensing electrode is indicated by the terminal S.

The semiconductor module200of the present example has the terminal P connected to the terminal C, the terminal N connected to the terminal E and the terminal CT connected to the terminal G. Also, the semiconductor module200has wiring connecting these terminals. Also, the semiconductor module200of the present example has a resistance210for current detection. The resistance210is connected between the terminal N and the terminal S. By measuring the drop voltage Ves in the resistance210, the magnitude of the current flowing through the sensing transistor portion110can be detected. The resistance value of the resistance210is, for example, 100Ω or more.

As the test of the semiconductor module200, it can be contemplated to detect the drop voltage Ves when a diode operation of the main element portion150is caused. The diode operation of the main element portion150refers to turning the main transistor portion70and the sensing transistor portion110to the OFF state, and causing a predetermined current to flow in the forward direction with respect to the main diode portion80. In the test of the present example, the second test current I2flows through the main diode portion80. The second test current I2is, for example, the rated current of the semiconductor device100during the diode operation.

Since the sensing transistor portion110is controlled to be in the OFF state, the current does not flow between the emitter region12and the collector region22in the sensing transistor portion110. As shown in the current path91inFIG.1, although the current flows through the base region14in the sensing transistor portion110and the cathode region82of the main diode portion80by the diode operation, since the current path91is extremely long, the current hardly flows. Accordingly, the drop voltage Ves is hardly generated.

On the other hand, when a defect93of the N type in the collector region22near the sensing transistor portion110is formed (refer toFIG.1), the current flows by the diode operation of the base region14and the defect93in the sensing transistor portion110. The current path92between the base region14and the defect93of the sensing transistor portion110is shorter than the current path91. Therefore, the current in the current path92becomes relatively large, and the drop voltage Ves becomes larger. The defect93may be a region where the donor of the N type is implanted by mistake, or may be a portion with the drift region18remained due to the damage of the collector region22. Current may flow between the defect93and the base region14of the sensing transistor portion110due to other reasons.

FIG.3illustrates measurement results of the drop voltage Ves for a plurality of semiconductor modules200. InFIG.3, a horizontal axis indicates a lot of the semiconductor module200, and a vertical axis indicates the drop voltage Ves.

In the test of the semiconductor module200, when the drop voltage Ves during the diode operation of the main element portion150exceeds a predetermined reference value Vref, the semiconductor module200may be determined as defective to be screened out. However, if defective products are screened out in the state of semiconductor module200, manufacturing costs incurred up to this point will be wasted. Therefore, it is preferred that the semiconductor device100with a portion such as the defect93can be screened out before being embedded into the semiconductor module200.

FIG.4illustrates a testing method of the semiconductor device100according to one embodiment of the present invention. In the present specification, the test of the semiconductor device100may be referred to as an element test or testing an element. The testing method in the present example includes operating an element S402, measuring an element S404and determining an element S406.

FIG.5illustrates an example of operating the element S402and measuring the element S404. During operating the element S402in the present example, in the semiconductor device100in a chip or wafer state, the diode operation of the sensing transistor portion110is caused. The chip state refers to a state of a chip singulated by cutting the semiconductor device100from the semiconductor wafer in which a plurality of semiconductor devices100are formed, and a state of not being embedded in the semiconductor module200. The wafer state also refers to a state of the semiconductor device100provided in the semiconductor wafer not being cut from the semiconductor wafer. A plurality of semiconductor devices100are formed in the semiconductor wafer. Each semiconductor device100has the structure described inFIG.1in either of the chip state or the wafer state. In the semiconductor device100, all electrodes such as an emitter electrode, a collector electrode, a gate electrode, and a sensing electrode are provided.

Also, the diode operation of the sensing transistor portion110refers to applying a gate voltage for controlling the sensing transistor portion110to be in the OFF state and causing a predetermined current to flow from the sensing electrode (terminal S) to the collector electrode (terminal C). In the example inFIG.5, the first test current I1flows through the sensing transistor portion110.

As shown inFIG.1, when the diode operation of the sensing transistor portion110of the semiconductor device100without the defect93is caused, the current flows along the current path91. On the other hand, when the diode operation of the sensing transistor portion110of the semiconductor device100with the defect93is caused, the current flows along the current path92. Since the length of the current path varies according to the presence or absence of the defect93and the position of the defect93, the diode characteristic of the sensing transistor portion110varies accordingly. Therefore, by measuring the diode characteristic of the sensing transistor portion110, similar to measuring the drop voltage Ves in the semiconductor module200, a test to determine the presence or absence of the defect93or the like can be performed. The diode characteristic refers to, for example, voltage-current characteristic showing the relationship between a voltage between main terminals of the sensing transistor portion110(Vsc) and the current flowing through the main terminal (I1). The main terminals of the sensing transistor portion110refer to the sensing electrode (terminal S) and the collector electrode (terminal C).

In measuring the element S404, the voltage-current characteristic is measured. In measuring the element S404, the current (I1) with respect to one voltage (Vsc) may be measured, or the current (I1) with respect to each of a plurality of voltages (Vsc) may be measured.

In operating the element S402, the voltage-current characteristic of the sensing transistor portion110is preferably measured while at least one of the main terminals of the main element portion150is opened. In the present example, the E terminal (emitter electrode) is in an open state. In this way, the voltage-current characteristic of the sensing transistor portion110can be measured accurately without operating the main element portion150.

FIG.6illustrates a measurement example of the voltage-current characteristic of the sensing transistor portion110in the plurality of semiconductor devices100. As described above, according to the presence or absence of the defect93and the position of the defect93and so on, the voltage-current characteristic of the sensing transistor portion110varies.

In determining the element S406, based on the voltage-current characteristic of the sensing transistor portion110, the defectiveness of the semiconductor device100is determined. In determining the element S406, by comparing a preset reference characteristic and the measured voltage-current characteristic, the defectiveness of the semiconductor device100may be determined.

For example, in determining the element S406, the defectiveness of each of the semiconductor devices100is determined based on the first test current I1when a predetermined testing voltage Vt is applied between main terminals of the sensing transistor portion110. The combination of the testing voltage Vt and the first test current I1corresponds to the voltage-current characteristic. In determining the element S406, if the first test current I1when the testing voltage Vt is applied exceeds the predetermined threshold current It, the semiconductor device100may be determined to be defective. The threshold current It corresponds to the reference characteristic described above.

The threshold current It is preferably set to be capable to distinguish the voltage-current characteristic of the semiconductor device100that is determined to be defective in the test using the drop voltage Ves (Ves: NG), and the voltage-current characteristic of the semiconductor device100that is determined to be non-defective in the test using the drop voltage Ves (Ves: OK).

It is easier for the first test current I1to flow through the semiconductor device100determined to be defective in the test using the drop voltage Ves when compared to the semiconductor device100determined to be non-defective. Therefore, the voltage-current characteristic of the defective sensing transistor portion110shifts toward the upper side (the direction of the current becoming larger) when compared to the voltage-current characteristic of the non-defective sensing transistor portion110. Therefore, by setting the threshold current It properly, similar to the test using the drop voltage Ves, the defectiveness can be detected according to the presence or absence and the position of the defect93, and so on.

Also, the threshold current It may be set to have a value corresponding to the reference value Vref that should be used in the test of the semiconductor module200. The reference value Vref may be a specification value required with respect to the semiconductor module200. By decreasing the threshold current It, the ratio of the semiconductor device100being determined as defective in the test using the voltage-current characteristic increases. Similarly, by decreasing the reference value Vref, the ratio of the semiconductor device100being determined as defective in the test using the drop voltage Ves increases. The threshold current It may be set so that the ratio of the semiconductor device determined to be defective in the test comparing the drop voltage Ves to the reference value Vref matches the ratio of the semiconductor device determined to be defective in the test using the voltage-current characteristic. The relationship between the reference value Vref and the threshold current It is preferably acquired in advance by experiments or simulations.

As described inFIG.1toFIG.6, by performing the test on the semiconductor device100in a chip or wafer state using the voltage-current characteristic of the sensing transistor portion110, the semiconductor device100in a chip or wafer state can be screened out in advance. Therefore, the defective rate can be reduced in the semiconductor module200, and the manufacturing costs can also be reduced. Also, the test using the voltage-current characteristic of the sensing transistor portion110can replace the test using the drop voltage Ves of the semiconductor module200. The test using the drop voltage Ves of the semiconductor module200may be performed, or may be omitted.

Note that the first test current I1may be smaller than a rated current of the main element portion150. The rated current of the main element portion150may be the rated current when the diode operation of the main element portion150is caused. The voltage-current characteristic of the sensing transistor portion110can still be measured even if the first test current I1is smaller than the rated current of the main element portion150. In operating the element S402and measuring the element S404, it can be contemplated to bring the probe for the test into direct contact with the C terminal and the S terminal of the semiconductor device100and apply the voltage and current. Since the relatively small first test current I1is used in the present example, even if the contact resistance between the terminal of the semiconductor device100and the probe for the test is high, it is easy to supply a current to the semiconductor device100. The first test current I1may be half or less, or may be 1/10 or less, of the rated current of the main element portion150. The first test current I1may be half or less, or may be 1/10 or less, of the second test current I2.

FIG.7illustrates an outline of a manufacturing method of the semiconductor module200. The manufacturing method in the present example includes forming an element S702, dicing S704, testing a chip S706, manufacturing a module S708and testing a module S710.

In forming the element S702, a plurality of semiconductor devices100are formed in the semiconductor substrate in a wafer state. In forming the element S702, the semiconductor device100in the wafer state may be tested. In forming the element S702, the element test described inFIG.4toFIG.6may be performed, or other tests may be performed.

In dicing S704, the plurality of semiconductor devices100are cut from the wafer and singulated (made into chips). In dicing S704, a process such as attaching a tape onto the wafer may be performed. Also, in dicing S704, the semiconductor device100determined as defective in the test in the wafer state may be sorted.

In testing the chip S706, the semiconductor device100in a chip state is tested. In testing the chip S706, the element test described inFIG.4toFIG.6may be performed, or other tests may be performed. Note that in at least one of forming the element S702or testing the chip S706, the element test described inFIG.4toFIG.6is performed. In testing the chip S706, a visual test of the semiconductor device100may also be included.

In manufacturing the module S708, the semiconductor module200is manufactured using the semiconductor device100determined to be non-defective in each test up to testing the chip S706. The semiconductor module200may include one or more semiconductor devices100, wiring, terminals, electrical elements and so on connected to the semiconductor device100, and a resin case configured to accommodate the semiconductor device100, wiring, terminals, electrical elements and so on.

In testing the module S710, the semiconductor module200is tested. In testing the module S710, the test described inFIG.2andFIG.3may be performed, or other tests may be performed. The semiconductor module200determined to be non-defective by testing the module S710may be shipped.

In the present example, in at least one of forming the element S702or testing the chip S706, the element test described inFIG.4toFIG.6is performed. Therefore, the ratio of defective semiconductor module200in testing the module S710can be reduced, and the manufacturing costs can also be reduced. Also, the test described inFIG.2andFIG.3in testing the module S710can be omitted.

FIG.8illustrates another example of the element test. The element test in the present example further includes acquiring a module characteristic S802and acquiring a correlation S804in addition to the example described inFIG.4. After acquiring the correlation S804, the processes after operating the element S402described inFIG.4may be performed.

In acquiring the module characteristic S802, information related to the drop voltage Ves described inFIG.2with the semiconductor device100being embedded in the semiconductor module200is acquired. That is, the drop voltage Ves when the test current I2flows through the main element portion150is measured in a state where a resistance210for current measurement is connected between the main terminal of the main element portion150(terminal E in the present example) and the main terminal of the sensing transistor portion110(terminal S in the present example). In acquiring the module characteristic S802, the reference semiconductor device having the same structure as the semiconductor device100under test may be embedded in the reference semiconductor module having the same structure as the semiconductor module200to measure the drop voltage Ves. In acquiring the module characteristic S802, the drop voltage Ves for each of the plurality of reference semiconductor devices may be measured. In acquiring the module characteristic S802, the drop voltage Ves may be measured for each of the reference semiconductor device in which the defect93is formed and the reference semiconductor device in which no defect93is formed.

In acquiring the correlation S804, the correlation between the drop voltage Ves and the voltage-current characteristic of the sensing transistor portion110is acquired. In acquiring the correlation S804, the voltage-current characteristic of the reference semiconductor device used in acquiring the module characteristic S802may be measured in advance to acquire the correlation with the drop voltage Ves measured in acquiring the module characteristic S802.

For example, in acquiring the correlation S804, as shown inFIG.6, the voltage-current characteristic of the reference semiconductor device where the drop voltage Ves satisfies the predetermined reference value (Ves: OK) may be distinguished from the voltage-current characteristic of the reference semiconductor device where the drop voltage Ves does not satisfy the predetermined reference value (Ves: NG).

After operating the element S402, similar to the example described inFIG.4, the semiconductor device100under test is tested. Note that in determining the element S406, based on the correlation acquired in acquiring the correlation S804, the defectiveness of the semiconductor device100is determined. In determining the element S406as described above, the voltage-current characteristic of the sensing transistor portion110is compared to the predetermined reference characteristics (for example, the threshold current It inFIG.6) to determine the defectiveness of the semiconductor device100. In determining the element S406in the present example, the threshold current It is set based on the correlation described above. In determining the element S406, as shown inFIG.6, the threshold current It is set so that the voltage-current characteristic where the drop voltage Ves satisfies the predetermined reference value (Ves: OK) can be distinguished from the voltage-current characteristic where the drop voltage Ves does not satisfy the predetermined reference value (Ves: NG). That is, the magnitude of the threshold current It is larger than the current with respect to the testing voltage Vt in the voltage-current characteristic in the non-defective case (Ves: OK), and smaller than the current with respect to the testing voltage Vt in the voltage-current characteristic in the defective case (Ves: NG). In this way, the result similar to the test using the drop voltage Ves can be obtained by the test using the voltage-current characteristic.

In operating the element S402and measuring the element S404described inFIG.4toFIG.8, the testing voltage Vt applied between main terminals of the sensing transistor portion110may be from 4V to 6V. As shown inFIG.6, the larger the testing voltage Vt, the larger the deviation between the current values of the voltage-current characteristic in the non-defective case (Ves: OK) and the voltage-current characteristic in the defective case (Ves: NG). Therefore, by increasing the testing voltage Vt, setting the threshold current It to determine the defectiveness becomes easier, also the accuracy of defectiveness determination is improved. The testing voltage Vt may be 4V or more, or may be 4.5V or more. On the other hand, if the testing voltage Vt and the first test current I1becomes larger, the heat generation at the contact portion between the terminal of the semiconductor device100and the probe for the test is increased. The testing voltage Vt may be 6V or less, or may be 5.5V or less.

Also, in determining the element S406, at least one of the voltage-current characteristic of the sensing transistor portion110or the reference characteristics (for example, the threshold current It) may be compensated based on the structure of the semiconductor device100. As an example, in determining the element S406, the threshold current It may be compensated for each lot of the semiconductor device100. The voltage-current characteristics shown inFIG.6vary according to the structure parameter showing the structure of the semiconductor device100. The structure parameter is, for example, the thickness of the semiconductor substrate10, the doping concentration of each region of the base region14, the drift region18and so on. The structure parameter may be a parameter affecting the resistance value of the current path when the sensing transistor portion110is under diode operation. When the resistance value of the current path varies, the voltage-current characteristic varies.

In determining the element S406, the value of the structure parameter in each lot of the semiconductor device100may be acquired. The value may be an average value within the lot. In determining the element S406, based on the value of the structure parameter of the lot, the threshold current It for the semiconductor device100belonging to the lot may be compensated. The relationship between the structure parameter value and the threshold current It value to be used may be acquired by experiments in advance, or may be acquired by simulations and so on. Also, instead of compensating the threshold current It, compensating the voltage-current characteristic may also obtain the similar effect.

FIG.9illustrates an example of the testing case performed in testing the module S710. In testing the module S710in the present example, the test described inFIG.2andFIG.3is performed. Testing the module S710in the present example includes operating a module S902, measuring a module S904and determining a module S906.

In operating the module S902, the semiconductor module200embedding the semiconductor device100determined to be non-defective in determining the element S406is operated as described inFIG.2. That is, in operating the module S902, the second test current I2flows through the main element portion150in a state where the resistance210for current measurement is connected between the main terminal of the main element portion150(terminal E in the present example) and the main terminal of the sensing transistor portion110(terminal S in the present example). As described inFIG.2, in operating the module S902and measuring the module S904, the main transistor portion70and the sensing transistor portion110are controlled to be in the OFF state. Also, the second test current I2is the current in the forward direction with respect to the main diode portion80.

In measuring the module S904, the drop voltage Ves in the resistance210when the second test current I2flows through the main element portion150is measured. The semiconductor module200may have a terminal for measuring the voltage between the two terminals of the resistance210.

In determining the module S906, the defectiveness of the semiconductor module200is determined based on the drop voltage Ves. In determining the module S906, as described inFIG.3, the defectiveness of the semiconductor module200may be determined based on whether the drop voltage Ves exceeds the predetermined reference value Vref. The semiconductor module200determined to be non-defective in determining the module S906may be shipped. As described inFIG.1toFIG.8, by performing the test on the semiconductor device100in the wafer state or the chip state using the voltage-current characteristic of the sensing transistor portion110, the test, which is equivalent to the test using the drop voltage Ves in the semiconductor module200, can be performed in advance. Therefore, the ratio of the semiconductor module200determined to be defective in determining the module S906can be reduced, and the manufacturing costs can also be reduced.

In the element test described inFIG.4orFIG.8, the plurality of semiconductor devices100may be tested in parallel. For example, the element test may be performed by bringing the probe for the measurement into contact with each of the plurality of semiconductor devices100in a wafer state. Since the relatively small first test current I1is used in the element test, it is relatively easy to test the plurality of semiconductor devices100in parallel.