Patent Application
20230069188
The present invention relates to a testing method and a manufacturing method of a semiconductor device.
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
Hereinafter, (some) embodiment(s) of the present invention will be described. The embodiment(s) do(es) not limit the invention according to the claims. And all the combinations of the features described in the embodiment(s) are not necessarily essential to means provided by aspects of the invention.
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%.
The semiconductor device 100 in the present example includes a main element portion 150 and a sensing transistor portion 110. The main element portion 150 includes a main transistor portion 70 and a main diode portion 80. The main transistor portion 70 may include, for example, IGBT element, or may include other transistors. The main diode portion 80 includes a reflux diode provided in anti-parallel with the main transistor portion 70. The semiconductor device 100 in the present example is a so-called reverse conducting IGBT (RC-IGBT).
The sensing transistor portion 110 is provided to detect a current flowing through the main element portion 150. The sensing transistor portion 110 has a structure similar to that of the main transistor portion 70, to which a control signal (for example, a gate voltage) input into the main transistor portion 70 is similarly input. Note that, in the xy plane, the area occupied by the sensing transistor portion 110 is smaller than the area occupied by the main transistor portion 70. The area of the sensing transistor portion 110 may be 1% or less, or may be 0.1% or less of the area of the main transistor portion 70. The magnitude of the current flowing through the sensing transistor portion 110 is the magnitude of a current flowing through the main transistor portion 70 multiplied by the value corresponding to the area ratio described above. Therefore, by measuring the current flowing through the sensing transistor portion 110, the magnitude of the current flowing through the main transistor portion 70 can be estimated.
The semiconductor device 100 in the present example further includes boundary portions 120 and a separating portion 130. The boundary portions 120 are provided on end portions of the main transistor portion 70, the main diode portion 80 and the sensing transistor portion 110 in the xy plane. Also, the separating portion 130 is arranged between the sensing transistor portion 110 and the main element portion 150 in the xy plane.
The semiconductor substrate 10 has a drift region 18 of an N− type. The drift region 18 is provided in each of the main element portion 150, the sensing transistor portion 110, the separating portion 130 and the boundary portions 120.
On the upper surface 21 side of the semiconductor substrate 10, one or more gate trench portions 40 and one or more dummy trench portions 30 are provided. In the present specification, the gate trench portion 40 and the dummy trench portion 30 may 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 substrate 10 are provided. The gate trench portion 40 is electrically connected to the gate electrode arranged above the upper surface 21 of the semiconductor substrate 10. The gate trench portion 40 functions as a gate electrode to which a gate voltage is applied. No gate voltage is applied to the dummy trench portion 30 and it does not function as a gate electrode. The emitter electrode described below may be connected to the dummy trench portion 30. Each trench portion is provided in a depth direction from the upper surface 21 to the drift region 18 of the semiconductor substrate 10.
A plurality of trench portions are arranged in a predetermined interval along a predetermined array direction. In the example of
Each of the main transistor portion 70 and the main diode portion 80 has a plurality of trench portions. In the main transistor portion 70 of the present example, one or more gate trench portions 40 and one or more dummy trench portions 30 are provided alternately along the array direction. Note that the array of the trench portions in the main transistor portion 70 is not limited to this. In the main diode portion 80 of the present example, the plurality of dummy trench portions 30 are provided along the array direction. The gate trench portion 40 is not provided in the main diode portion 80 of 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 substrate 10. In the mesa portion of the main transistor portion 70, emitter regions 12 of an N+ type and base regions 14 of a P type are provided in order from the upper surface 21 side of the semiconductor substrate 10. The emitter region 12 has a doping concentration higher than the drift region 18. The drift region 18 is provided below the base region 14.
The emitter region 12 is exposed from the upper surface 21 of the semiconductor substrate 10, and is provided to be in contact with the trench portion in the xy plane. The base region 14 is provided below the emitter region 12 and is provided to be in contact with the trench portion in the xy plane. The emitter region 12 and the base region 14 are connected electrically to the emitter electrode provided above the upper surface 21 of the semiconductor substrate 10. The base region 14 may be connected to the emitter electrode via the contact region 15 of the P+ type provided on the upper surface 21 of the semiconductor substrate 10. The doping concentration of the contact region 15 is higher than the doping concentration of the base region 14. On the upper surface 21 of the semiconductor substrate 10, the emitter regions 12 and the contact regions 15 may be arranged alternately along the y axis direction.
In the mesa portion of the main diode portion 80, the base region 14 of the P type is provided to be in contact with the upper surface 21 of the semiconductor substrate 10. The drift region 18 is provided below the base region 14.
Each trench portion reaches the drift region 18 penetrating the base region 14 from the upper surface 21 of the semiconductor substrate 10. In the region with the emitter region 12 provided, each trench portion may penetrate the emitter region 12 as well. When the predetermined gate voltage is applied to the gate trench portion 40, a channel is formed by the electron inversion layer on the surface layer of the interface that is in contact with the gate trench portion 40 in the base regions 14. A current flows through the channel between the emitter regions 12 and the drift region 18.
In the main transistor portion 70, in the region in contact with the lower surface 23 of the semiconductor substrate 10, a collector region 22 of the P+ type is provided. The doping concentration of the collector region 22 is higher than the doping concentration of the base region 14.
In the main diode portion 80, in the region in contact with the lower surface 23 of the semiconductor substrate 10, a cathode region 82 of the N+ type is provided. The doping concentration of the cathode region 82 is higher than the doping concentration of the drift region 18. The collector region 22 and the cathode region 82 are connected to the collector electrode provided on the lower surface 23 of the semiconductor substrate 10. The gate electrode, emitter electrode and collector electrode described above may be formed of a metallic material such as aluminum.
The sensing transistor portion 110 has a structure similar to the main transistor portion 70. Note that, in the sensing transistor portion 110, the dummy trench portion 30 may not be provided. Also above the sensing transistor portion 110, 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 portion 120, one or more trench portions are provided. The trench portion provided in the boundary portion 120 may be a dummy trench portion 30, or may be a gate trench portion 40, or may be both of the dummy trench portion 30 and the gate trench portion 40. In the mesa portion of the boundary portion 120 in the present example is provided with the contact region 15 and the base region 14. The contact region 15 is exposed from the upper surface 21. The base region 14 is provided between the contact region 15 and the drift region 18. In the boundary portion 120, the collector region 22 in contact with the lower surface 23 of the semiconductor substrate 10 may be provided.
In the separating portion 130, a well region 11 of the P+ type is provided. The well region 11 has a doping concentration higher than the base region 14. Also the well region 11 is provided from the upper surface 21 to the position deeper than the trench portion in the semiconductor substrate 10. In the separating portion 130, the base region 14 sandwiched between the well regions 11 in the xy plane may be provided. By providing the separating portion 130, the movement of carriers between the sensing transistor portion 110 and the main element portion 150 are suppressed.
As described in
The semiconductor module 200 of 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 module 200 has wiring connecting these terminals. Also, the semiconductor module 200 of the present example has a resistance 210 for current detection. The resistance 210 is connected between the terminal N and the terminal S. By measuring the drop voltage Ves in the resistance 210, the magnitude of the current flowing through the sensing transistor portion 110 can be detected. The resistance value of the resistance 210 is, for example, 100Ω or more.
As the test of the semiconductor module 200, it can be contemplated to detect the drop voltage Ves when a diode operation of the main element portion 150 is caused. The diode operation of the main element portion 150 refers to turning the main transistor portion 70 and the sensing transistor portion 110 to the OFF state, and causing a predetermined current to flow in the forward direction with respect to the main diode portion 80. In the test of the present example, the second test current I2 flows through the main diode portion 80. The second test current I2 is, for example, the rated current of the semiconductor device 100 during the diode operation.
Since the sensing transistor portion 110 is controlled to be in the OFF state, the current does not flow between the emitter region 12 and the collector region 22 in the sensing transistor portion 110. As shown in the current path 91 in
On the other hand, when a defect 93 of the N type in the collector region 22 near the sensing transistor portion 110 is formed (refer to
In the test of the semiconductor module 200, when the drop voltage Ves during the diode operation of the main element portion 150 exceeds a predetermined reference value Vref, the semiconductor module 200 may be determined as defective to be screened out. However, if defective products are screened out in the state of semiconductor module 200, manufacturing costs incurred up to this point will be wasted. Therefore, it is preferred that the semiconductor device 100 with a portion such as the defect 93 can be screened out before being embedded into the semiconductor module 200.
Also, the diode operation of the sensing transistor portion 110 refers to applying a gate voltage for controlling the sensing transistor portion 110 to 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 in
As shown in
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 portion 110 is preferably measured while at least one of the main terminals of the main element portion 150 is 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 portion 110 can be measured accurately without operating the main element portion 150.
In determining the element S406, based on the voltage-current characteristic of the sensing transistor portion 110, the defectiveness of the semiconductor device 100 is determined. In determining the element S406, by comparing a preset reference characteristic and the measured voltage-current characteristic, the defectiveness of the semiconductor device 100 may be determined.
For example, in determining the element S406, the defectiveness of each of the semiconductor devices 100 is determined based on the first test current I1 when a predetermined testing voltage Vt is applied between main terminals of the sensing transistor portion 110. The combination of the testing voltage Vt and the first test current I1 corresponds to the voltage-current characteristic. In determining the element S406, if the first test current I1 when the testing voltage Vt is applied exceeds the predetermined threshold current It, the semiconductor device 100 may 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 device 100 that is determined to be defective in the test using the drop voltage Ves (Ves: NG), and the voltage-current characteristic of the semiconductor device 100 that is determined to be non-defective in the test using the drop voltage Ves (Ves: OK).
It is easier for the first test current I1 to flow through the semiconductor device 100 determined to be defective in the test using the drop voltage Ves when compared to the semiconductor device 100 determined to be non-defective. Therefore, the voltage-current characteristic of the defective sensing transistor portion 110 shifts toward the upper side (the direction of the current becoming larger) when compared to the voltage-current characteristic of the non-defective sensing transistor portion 110. 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 defect 93, 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 module 200. The reference value Vref may be a specification value required with respect to the semiconductor module 200. By decreasing the threshold current It, the ratio of the semiconductor device 100 being determined as defective in the test using the voltage-current characteristic increases. Similarly, by decreasing the reference value Vref, the ratio of the semiconductor device 100 being 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 in
Note that the first test current I1 may be smaller than a rated current of the main element portion 150. The rated current of the main element portion 150 may be the rated current when the diode operation of the main element portion 150 is caused. The voltage-current characteristic of the sensing transistor portion 110 can still be measured even if the first test current I1 is smaller than the rated current of the main element portion 150. In operating the element S402 and 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 device 100 and apply the voltage and current. Since the relatively small first test current I1 is used in the present example, even if the contact resistance between the terminal of the semiconductor device 100 and the probe for the test is high, it is easy to supply a current to the semiconductor device 100. The first test current I1 may be half or less, or may be 1/10 or less, of the rated current of the main element portion 150. The first test current I1 may be half or less, or may be 1/10 or less, of the second test current I2.
In forming the element S702, a plurality of semiconductor devices 100 are formed in the semiconductor substrate in a wafer state. In forming the element S702, the semiconductor device 100 in the wafer state may be tested. In forming the element S702, the element test described in
In dicing S704, the plurality of semiconductor devices 100 are 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 device 100 determined as defective in the test in the wafer state may be sorted.
In testing the chip S706, the semiconductor device 100 in a chip state is tested. In testing the chip S706, the element test described in
In manufacturing the module S708, the semiconductor module 200 is manufactured using the semiconductor device 100 determined to be non-defective in each test up to testing the chip S706. The semiconductor module 200 may include one or more semiconductor devices 100, wiring, terminals, electrical elements and so on connected to the semiconductor device 100, and a resin case configured to accommodate the semiconductor device 100, wiring, terminals, electrical elements and so on.
In testing the module S710, the semiconductor module 200 is tested. In testing the module S710, the test described in
In the present example, in at least one of forming the element S702 or testing the chip S706, the element test described in
In acquiring the module characteristic S802, information related to the drop voltage Ves described in
In acquiring the correlation S804, the correlation between the drop voltage Ves and the voltage-current characteristic of the sensing transistor portion 110 is acquired. In acquiring the correlation S804, the voltage-current characteristic of the reference semiconductor device used in acquiring the module characteristic S802 may 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 in
After operating the element S402, similar to the example described in
In operating the element S402 and measuring the element S404 described in
Also, in determining the element S406, at least one of the voltage-current characteristic of the sensing transistor portion 110 or the reference characteristics (for example, the threshold current It) may be compensated based on the structure of the semiconductor device 100. As an example, in determining the element S406, the threshold current It may be compensated for each lot of the semiconductor device 100. The voltage-current characteristics shown in
In determining the element S406, the value of the structure parameter in each lot of the semiconductor device 100 may 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 device 100 belonging 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.
In operating the module S902, the semiconductor module 200 embedding the semiconductor device 100 determined to be non-defective in determining the element S406 is operated as described in
In measuring the module S904, the drop voltage Ves in the resistance 210 when the second test current I2 flows through the main element portion 150 is measured. The semiconductor module 200 may have a terminal for measuring the voltage between the two terminals of the resistance 210.
In determining the module S906, the defectiveness of the semiconductor module 200 is determined based on the drop voltage Ves. In determining the module S906, as described in
In the element test described in
While the embodiments of the present invention have been described, the technical scope of the invention is not limited to the above described embodiments. It is apparent to persons skilled in the art that various alterations and improvements can be added to the above-described embodiments. It is also apparent from the scope of the claims that the embodiments added with such alterations or improvements can be included in the technical scope of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-142337 | Sep 2021 | JP | national |
