Test circuit and test method of power device

Abstract

The invention provides a test circuit for a power device, and the circuit comprises a first excitation and measurement module which has a first end connected with the gate end of a to-be-tested power device through a first switching device, has a second end connected with the source end of the to-be-tested power device, and is used for applying a voltage to the gate end of the to-be-tested power device; the first end of the second excitation and measurement module is connected with the drain end of the to-be-tested power device through a second switching device, the second end of the second excitation and measurement module is connected with the source end of the to-be-tested power device, and the second excitation and measurement module is used for applying first test current to the drain end and the source end of the to-be-tested power device and measuring drain-source voltage of the to-be-tested power device to obtain on resistance of the to-be-tested power device; the first end of the third excitation and measurement module is connected with the drain end of the to-be-measured power device through a third switching device, the second end of the third excitation and measurement module is connected with the source end of the to-be-measured power device, and the third excitation and measurement module is used for applying bias high voltage to the drain end and the source end of the to-be-measured power device and measuring drain end leakage current of the to-be-measured power device. According to the invention, the problems of complex test circuit, long test time and the like of the existing test scheme are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic circuits, and in particular to a test circuit and a test method for a power device. Background Art

[0002] As a new generation of power devices, GaN devices have always attracted much attention. Due to their excellent performance, they are now increasingly used in high-frequency and high-power fields. However, due to various stress conditions encountered during the switching process, some charges are captured, resulting in current collapse, causing higher losses, making their actual performance lower than the theoretical performance, affecting reliability, and causing hidden dangers in practical applications. Research on the dynamic characteristics of GaN devices has always been the focus of technicians, and screening out problematic devices through electrical testing is even more important.

[0003] Currently, a double pulse test is used to implement dynamic resistance testing of GaN devices. The principle is as follows: first, in the ON state, a current is applied to the GaN device and the voltage of the GaN device is tested, and the on-resistance is calculated by Ohm's law; then, the device enters the OFF state and a high voltage bias is applied to both ends of the source and drain of the GaN device; finally, the device enters the ON state and the on-resistance is tested again.

[0004] The dynamic resistance of GaN devices is a transient phenomenon and needs to be tested under pulse conditions. This places very strict requirements on the design of the test circuit and the test cost is relatively high. Moreover, the existing test circuits are complex, the test time is long, and the test efficiency is low, which will seriously affect production capacity during the mass production stage. In addition, the existing test circuits need to be used with external circuits or pulse generators at the board level, which is only suitable for small-scale or single-station testing. It is not feasible when multiple chips are tested simultaneously, such as reliability testing and application-end testing. Summary of the invention

[0005] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a test circuit and a test method for a power device, so as to solve the problems of complex test circuit and long test time when the dynamic resistance test of gallium nitride devices is performed by the existing double pulse test.

[0006] To achieve the above-mentioned object and other related objects, the present invention provides a test circuit for a power device, the test circuit comprising:

[0007] A first excitation and measurement module, a second excitation and measurement module, a third excitation and measurement module, a first switching device, a second switching device and a third switching device;

[0008] The first end of the first excitation and measurement module is connected to the gate end of the power device to be measured through the first switch device, and the second end is connected to the source end of the power device to be measured, so as to apply a voltage to the gate end of the power device to be measured;

[0009] The first end of the second excitation and measurement module is connected to the drain end of the power device to be tested through the second switch device, and the second end is connected to the source end of the power device to be tested, and is used to apply a first test current to both ends of the drain and source of the power device to be tested, and measure the drain-source voltage of the power device to be tested to obtain the on-resistance of the power device to be tested;

[0010] The first end of the third excitation and measurement module is connected to the drain end of the power device to be tested through the third switching device, and the second end is connected to the source end of the power device to be tested, and is used to apply a bias high voltage to both ends of the drain and source of the power device to be tested, and measure the drain leakage current of the power device to be tested.

[0011] Optionally, the test circuit further comprises: a load resistor and a clamping and measuring module;

[0012] The load resistor is connected between the third excitation and measurement module and the third switch device, and is used to set a second test current;

[0013] The clamping and measuring module is connected between the drain-source and source terminals of the power device to be tested, and is used to obtain the on-resistance of the power device to be tested by measuring the drain-source voltage of the power device to be tested when the voltage across the drain-source of the power device to be tested is less than the clamping voltage.

[0014] Optionally, the third excitation and measurement module includes: a high-voltage excitation and measurement unit, a fourth switching device and a first capacitor, the high-voltage excitation and measurement unit is connected in series with the fourth switching device and then connected in parallel with the first capacitor; the power device to be measured includes a gallium nitride device.

[0015] Optionally, the test circuit further includes:

[0016] a fifth switch device, connected between the gate terminal and the drain terminal of the power device to be tested; at this time, the voltage applied by the first excitation and measurement module to the gate terminal of the power device to be tested includes a step-by-step increasing driving voltage, and the first excitation and measurement module is also used to measure the drain-source current of the power device to be tested to obtain the threshold voltage of the power device to be tested;

[0017] And / or, a sixth switching device is connected between the drain terminal and the source terminal of the power device to be tested; at this time, the voltage applied to the gate terminal of the power device to be tested by the first excitation and measurement module includes a bias voltage, and the first excitation and measurement module is also used to measure the gate leakage current of the power device to be tested.

[0018] Optionally, the first switch device, the second switch device, the third switch device, the fifth switch device and the sixth switch device are implemented using gallium nitride devices; in this case, the test circuit further includes: a gate control module for controlling the on and off of each gallium nitride device.

[0019] The present invention also provides a method for testing a power device, based on the test circuit as described in any one of the above items, at least a dynamic on-resistance test is performed on the power device to be tested, and the test method comprises:

[0020] Before bias is applied, performing an on-resistance test on the power device to be tested;

[0021] After the test is completed, applying a bias to the power device to be tested;

[0022] After the bias is applied, an on-resistance test is performed on the power device to be tested.

[0023] Optionally, before or after bias is applied, the method for performing an on-resistance test on the power device to be tested includes:

[0024] Control the first switching device and the second switching device to be turned on, apply a turn-on voltage to the gate terminal of the power device to be tested through the first excitation and measurement module to put the power device to be tested in a turn-on state, apply a first test current to the drain-source terminals of the power device to be tested through the second excitation and measurement module, and measure the drain-source voltage of the power device to be tested to obtain the on-resistance of the power device to be tested.

[0025] Optionally, the method for applying a bias to the power device to be tested includes:

[0026] Control the first switching device and the third switching device to be turned on, apply zero voltage to the gate terminal of the power device to be tested through the first excitation and measurement module, apply bias high voltage to the drain-source terminals of the power device to be tested through the third excitation and measurement module, and measure the drain leakage current of the power device to be tested.

[0027] Optionally, when the test circuit includes a load resistor and a clamp and measurement module, after bias is applied, the method for performing an on-resistance test on the power device to be tested includes:

[0028] Keep the first switching device and the third switching device turned on, apply a turn-on voltage to the gate terminal of the power device to be tested through the first excitation and measurement module to turn on the power device to be tested, and measure the drain-source voltage of the power device to be tested through the clamping and measurement module to obtain the on-resistance of the power device to be tested.

[0029] Optionally, when the test circuit includes a fifth switch device, the test method further includes: a step of performing a dynamic threshold voltage test on the power device to be tested;

[0030] And / or, when the test circuit includes a sixth switching device, the test method further includes: a step of performing a gate leakage test on the power device to be tested.

[0031] Optionally, the method for performing a dynamic threshold voltage test on the power device to be tested includes:

[0032] Before bias is applied, a threshold voltage test is performed on the power device to be tested;

[0033] After the test is completed, applying a bias to the power device to be tested;

[0034] After the bias is applied, a threshold voltage test is performed on the power device to be tested.

[0035] Optionally, before or after bias is applied, the method for performing a threshold voltage test on the power device to be tested includes:

[0036] Controlling the fifth switch device to be turned on, short-circuiting the gate terminal and the drain terminal of the power device to be tested, and controlling the first switch device to be turned on, applying a driving voltage to the gate terminal of the power device to be tested through the first excitation and measurement module, wherein the driving voltage increases step by step from a preset value; measuring the drain-source current of the power device to be tested through the first excitation and measurement module, and stopping the increase of the driving voltage when the drain-source current reaches a set current, so as to obtain the threshold voltage of the power device to be tested based on the current driving voltage;

[0037] The method of applying bias to the power device to be tested comprises:

[0038] Control the first switching device and the third switching device to be turned on, apply zero voltage to the gate terminal of the power device to be tested through the first excitation and measurement module, apply bias high voltage to the drain-source terminals of the power device to be tested through the third excitation and measurement module, and measure the drain leakage current of the power device to be tested.

[0039] Optionally, the method for performing a gate leakage test on the power device to be tested includes:

[0040] The sixth switch device is controlled to be turned on, the drain and source terminals of the power device to be tested are short-circuited, and the first switch device is controlled to be turned on, a bias voltage is applied to the gate terminal of the power device to be tested through the first excitation and measurement module, and the gate leakage current of the power device to be tested is measured.

[0041] As described above, the test circuit and test method of the power device of the present invention utilize high-frequency switching devices to complete rapid circuit switching in a very short time, and can simulate the effect of a similar pulse test in the DC test stage. The dynamic characteristics of the power device can be tested without complex pulse testing, which is convenient for screening out failed devices. At the same time, conventional DC testing of the power device can be taken into account, saving test time and cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It shows a schematic diagram of the structure of the test circuit in the first embodiment of the present invention.

[0043] Figure 2 Shown is a flow chart of the testing method in Embodiment 1 of the present invention.

[0044] Figure 3 It shows a schematic diagram of the structure of the test circuit in the second embodiment of the present invention.

[0045] Figure 4 It shows a schematic diagram of the structure of the test circuit in the third embodiment of the present invention.

[0046] Figure 5 Shown is a flow chart of the testing method in Embodiment 3 of the present invention.

[0047] Figure 6 It shows a schematic diagram of the structure of the test circuit in the fourth embodiment of the present invention.

[0048] Figure 7 Shown is a flow chart of the testing method in Embodiment 4 of the present invention.

[0049] Figure 8 It shows a schematic diagram of the structure of the test circuit in the fifth embodiment of the present invention.

[0050] Fig. 9 Shown is a flow chart of the testing method in Embodiment 5 of the present invention.

[0051] Component number description

[0052] 100 Test Circuit

[0053] 110 First Excitation and Measurement Module

[0054] 120 Second excitation and measurement module

[0055] 130 Third Excitation and Measurement Module

[0056] DETAILED DESCRIPTION

[0057] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0058] See also Figures 1 to 9 It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner, and the illustrations only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the form, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0059] Embodiment 1

[0060] like Figure 1 As shown, this embodiment provides a power device test circuit 100, including: a first excitation and measurement module 110, a second excitation and measurement module 120, a third excitation and measurement module 130, a first switch device K1, a second switch device K2 and a third switch device K3. Wherein:

[0061] The first end of the first excitation and measurement module 110 is connected to the gate terminal of the power device DUT under test through the first switch device K1, and the second end is connected to the source terminal of the power device DUT under test, for applying a voltage to the gate terminal of the power device DUT under test, such as a turn-on voltage or zero voltage.

[0062] In this embodiment, the first excitation and measurement module 110 applies a turn-on voltage to the gate terminal of the power device DUT to be tested, so as to cooperate with the second excitation and measurement module 120 to perform an on-resistance test on the power device DUT to be tested; the first excitation and measurement module 110 applies a zero voltage to the gate terminal of the power device DUT to be tested, so as to cooperate with the third excitation and measurement module 130 to apply a bias high voltage to both ends of the drain and source of the power device DUT to be tested. It should be noted that the value of the turn-on voltage is determined by the type of the power device DUT to be tested. For example, when the power device DUT to be tested is a gallium nitride device, its turn-on voltage is usually 5V-6V.

[0063] As an example, the first excitation and measurement module 110 can be implemented by an excitation source or by an SMU (SourceMeasure Unit), which has no substantial effect on this embodiment. For SMU, it is used as a voltage source when working in FV (Force Voltage) mode, as a current source when working in FI (Force Current) mode, can measure voltage when working in MV (Measure Voltage) mode, and can measure current when working in MI (Measure Current) mode. By combining the above working modes, SMU can have multiple functions; in this embodiment, if the first excitation and measurement module 110 is implemented by SMU, it mainly works in FV mode.

[0064] The first end of the second excitation and measurement module 120 is connected to the drain end of the power device DUT to be tested through the second switching device K2, and the second end is connected to the source end of the power device DUT to be tested, and is used to apply a first test current to the drain and source ends of the power device DUT to be tested, and measure the drain-source voltage of the power device DUT to be tested to obtain the on-resistance of the power device DUT to be tested; wherein the on-resistance is equal to the ratio of the drain-source voltage to the first test current.

[0065] As an example, the second excitation and measurement module 120 is implemented using SMU, which mainly works in FI mode and MV mode, namely FIMV mode; in practical applications, since the actual current provided by SMU may have an error with the theoretical current, such as the actual current is slightly smaller than the theoretical current, SMU is usually used to measure the drain-source current of the power device DUT to obtain the actual value of the first test current and thereby obtain the on-resistance of the power device DUT to be tested. At this time, SMU mainly works in FI mode, MV mode and MI mode, namely FIMVMI mode. It should be noted that the theoretical value of the first test current should be set according to actual needs, and this embodiment does not limit this.

[0066] The first end of the third excitation and measurement module 130 is connected to the drain end of the power device DUT under test through the third switching device K3, and the second end is connected to the source end of the power device DUT under test, and is used to apply a bias high voltage to both ends of the drain and source of the power device DUT under test, and measure the drain leakage current of the power device DUT under test.

[0067] Specifically, the third excitation and measurement module 130 includes: a high-voltage excitation and measurement unit 131, a fourth switch device K4 and a first capacitor C1. The high-voltage excitation and measurement unit 131 is connected in series with the fourth switch device K4 and then connected in parallel with the first capacitor C1 between the third switch device K3 and the source end of the power device DUT to be tested.

[0068] As an example, the high voltage excitation and measurement unit 131 is implemented by SMU, which mainly works in FV mode and MI mode, namely FVMI mode; the fourth switch device K4 is implemented by a relay. It should be noted that the value of the bias high voltage is determined by the withstand voltage of the power device DUT to be tested, for example, the value of the bias high voltage should be equal to or slightly greater than the maximum withstand voltage value of the power device DUT to be tested.

[0069] As an example, the first switch device K1, the second switch device K2 and the third switch device K3 are implemented by gallium nitride devices; in this case, the test circuit 100 further includes: a gate control module 140 for controlling the on and off of each gallium nitride device. Using gallium nitride devices as switch devices can achieve ultra-fast on and off of the switch devices (operating frequency can reach GHz), which is conducive to the rapid testing of the test circuit; in addition, each switch device is controlled by a unified gate control module 140, which can achieve high-precision control of the switch devices.

[0070] In this embodiment, when the third switch device K3 is turned off and the fourth switch device K4 is turned on, the high-voltage excitation and measurement unit 131 charges the first capacitor C1, and after the third switch device K3 is turned on, the first capacitor C1 is discharged to apply a bias high voltage to both ends of the drain source of the power device to be tested DUT, and the leakage current of the drain end of the power device to be tested DUT is measured by the high-voltage excitation and measurement unit 131. By replacing the high-voltage source with a capacitor to apply a bias high voltage to both ends of the drain source of the power device to be tested DUT, the test speed of the test circuit can be further improved by using the fast discharge performance of the capacitor.

[0071] The power device DUT to be tested may be a gallium nitride device or a silicon device, etc. This has no substantial impact on this embodiment. This embodiment takes the case where the power device DUT to be tested is a gallium nitride device as an example. In practical applications, the source end of the power device DUT to be tested is connected to the reference ground.

[0072] like Figure 2 As shown, this embodiment also provides a power device testing method, including steps S11 to S13; the testing method is implemented based on the test circuit 100 as described above, for example, a dynamic on-resistance test is performed on the power device DUT based on the test circuit 100 as described above. Wherein:

[0073] Step S11: before bias is applied, an on-resistance test is performed on the power device under test DUT.

[0074] Specifically, the method for conducting an on-resistance test on the power device DUT to be tested includes: controlling the first switch device K1 and the second switch device K2 to be turned on, applying a turn-on voltage to the gate terminal of the power device DUT to be tested through the first excitation and measurement module 110, so that the power device DUT to be tested is in an on state, applying a first test current to the drain-source terminals of the power device DUT to be tested through the second excitation and measurement module 120, and measuring the drain-source voltage of the power device DUT to be tested to obtain the on-resistance of the power device DUT to be tested; thereafter, controlling the first switch device K1 and the second switch device K2 to be turned off. Of course, in order to improve the test accuracy, the second excitation and measurement module 120 can also obtain the actual value of the first test current by measuring the drain-source current of the power device DUT to be tested and thereby obtain the on-resistance of the power device DUT to be tested. Step S12: After the test is completed, bias the power device DUT to be tested.

[0075] Specifically, the method for applying bias to the power device DUT under test includes: controlling the first switch device K1 and the third switch device K3 to be turned on, applying zero voltage to the gate terminal of the power device DUT under test through the first excitation and measurement module 110, applying bias high voltage to the drain-source terminals of the power device DUT under test through the third excitation and measurement module 130, and measuring the drain leakage current of the power device DUT under test; thereafter, controlling the first switch device K1 and the third switch device K3 to be turned off.

[0076] In this step, when the third excitation and measurement module 130 includes a high-voltage excitation and measurement unit 131, a fourth switch device K4 and a first capacitor C1, the fourth switch device K4 is turned on at the beginning of the test and turned off after the bias application is completed, so that the high-voltage excitation and measurement unit 131 has sufficient time to charge the first capacitor C1, and can perform current testing on the power device DUT under test during the bias application process.

[0077] It should be noted that, since the power device DUT to be tested in this embodiment is a gallium nitride device, it is impossible to perform a BV test (high-voltage bias test) directly. Therefore, the BV test is characterized by an IDSS test (drain current test at zero gate voltage). Of course, when the power device DUT to be tested is a non-gallium nitride device such as a silicon device, the BV test can also be directly used. At this time, the third excitation and measurement module 130 does not need to perform a current test, and the fourth switch device K4 can be turned off when this step is executed. However, for the IDSS test and the VB test, the time for applying the bias high voltage is set by controlling the on-time of the third switch device K3 to complete the bias application.

[0078] Step S13: After the bias is applied, an on-resistance test is performed on the power device under test DUT; the method of the on-resistance test in this step is the same as that in step S11, and will not be repeated here.

[0079] In this embodiment, the dynamic on-resistance of the device is characterized based on a ratio. The on-resistance of the device measured in step S11 is RDSON1, and the on-resistance of the device measured in step S13 is RDSON2. Then the dynamic on-resistance ΔRDSON=(RDSON2-RDSON1) / RDSON1.

[0080] The test circuit 100 of this embodiment can realize fast testing, so it can simulate similar pulse testing through DC testing, so as to realize the testing of dynamic characteristics of power devices. In fact, the above test method can be performed in the conventional DC test stage, such as in the CP test (mid-terminal electrical test) or FT test (terminal electrical test) stage.

[0081] Furthermore, before executing step S11, the test method of this embodiment further includes step S01 and step S02; after executing step S13, the test method of this embodiment further includes step S4. Among them:

[0082] Step S01: performing an open circuit / short circuit test on a power device under test DUT to determine whether there is an open circuit or short circuit problem in the circuit connection of the power device under test DUT.

[0083] Step S02: perform DC parameter test on the power device DUT to be tested; for example, perform on-resistance test and IDSS test on the power device DUT to be tested; of course, since step S1 and step S2 are on-resistance test and IDSS test, the parameter test of on-resistance can be completed by step S1, and the parameter test of IDSS can be completed by step S2.

[0084] Step S4: Conduct an electrical inspection on the power device DUT to determine whether the device is damaged; for example, conduct an on-resistance test and a low-voltage IDSS test on the power device DUT in sequence (the only difference from the above IDSS test is the bias size).

[0085] Embodiment 2

[0086] like Figure 3 As shown, the difference between this embodiment and the first embodiment is that the test circuit 100 further includes: a load resistor R1 and a clamping and measuring module 150. Among them:

[0087] The load resistor R1 is connected between the third excitation and measurement module 130 and the third switch device K3, and is used to set the second test current; wherein the second test current is equal to the ratio of the bias high voltage to the load resistor. By reasonably designing the value of the load resistor R1, the desired second test current can be obtained.

[0088] The clamping and measuring module 150 is connected between the drain-source and source terminals of the power device DUT to be tested, and is used to obtain the on-resistance of the power device DUT to be tested by measuring the drain-source voltage of the power device DUT to be tested when the voltage across the drain-source terminals of the power device DUT to be tested is less than the clamping voltage. Specifically, when the voltage across the drain-source terminals of the power device DUT to be tested is greater than or equal to the clamping voltage, the clamping and measuring module 150 clamps the voltage to make it equal to the clamping voltage; when the voltage across the drain-source terminals of the power device DUT to be tested is less than the clamping voltage, the clamping and measuring module 150 measures the voltage to obtain the drain-source voltage to obtain the on-resistance of the power device DUT to be tested; wherein the on-resistance is equal to the ratio of the drain-source voltage to the second test current.

[0089] The difference between the test method of this embodiment and the first embodiment lies in step S13. The first embodiment involves a soft switch form on-resistance test, while the present embodiment involves a hard switch form on-resistance test. In order to perform this test, after step S12 is performed, it is not necessary to control the first switch device K1 and the third switch device K3 to be turned off, that is, the first switch device K1 and the third switch device K3 are kept turned on. At this time,

[0090] The method for performing on-resistance test on the power device DUT to be tested in step S13 includes: applying a turn-on voltage to the gate terminal of the power device DUT to be tested through the first excitation and measurement module 110 to put the power device DUT to be tested in an on state, and measuring the drain-source voltage of the power device DUT to be tested through the clamping and measurement module 150 to obtain the on-resistance of the power device DUT to be tested; thereafter, controlling the first switch device K1 and the third switch device K3 to be turned off.

[0091] In this embodiment, when the power device DUT to be tested is in the on state, the voltage across the load resistor R1 can be approximately regarded as the bias high voltage, and the current flowing through the load resistor R1 is the second test current; since the voltage applied to the gate terminal of the power device DUT to be tested is switched from zero voltage to the on voltage, the voltage across its drain and source will drop from the bias high voltage to a voltage close to zero. When measuring its drain-source voltage through the clamping and measuring module 150, there is no need to use a large-range measurement circuit. Only a small-range measurement circuit is needed to measure the drain-source voltage, thereby improving the measurement accuracy (for example, the bias high voltage is 650V and the clamping voltage is 5V. When there is no clamping function, a large range of 0-700V is required to measure the drain-source voltage, and when there is a clamping function, only a small range of 0-6V is needed, thereby greatly improving the measurement accuracy).

[0092] Embodiment 3

[0093] like Figure 4As shown, the difference between this embodiment and the first and second embodiments is that the test circuit 100 also includes a fifth switching device K5, which is connected between the gate and drain terminals of the power device DUT to be tested; at this time, the voltage applied to the gate terminal of the power device DUT to be tested by the first excitation and measurement module 110 also includes a step-by-step increasing driving voltage, and the first excitation and measurement module 110 is also used to measure the drain-source current of the power device DUT to be tested to obtain the threshold voltage of the power device DUT to be tested.

[0094] Specifically, after measuring the drain-source current of the power device DUT to be tested, the first excitation and measurement module 110 also compares the drain-source current with the set current, and stops increasing the driving voltage when the drain-source current reaches the set current, so as to obtain the threshold voltage of the power device DUT to be tested based on the current driving voltage, such as using the current driving voltage as the threshold voltage of the power device DUT to be tested. It should be noted that the so-called current driving voltage refers to the voltage value maintained by the driving voltage after stopping the increase.

[0095] In a possible implementation, the first excitation and measurement module 110 controls the value of the driving voltage to increase step by step from a preset value based on the step value. For example, the value of the driving voltage initially output by the first excitation and measurement module 110 is the preset value; after the first comparison, the drain-source current does not reach the set current, and the output driving voltage value is the preset value + the step value; after the second comparison, the drain-source current still does not reach the set current, and the output driving voltage value is the preset value + 2 times the step value; and so on, until the drain-source current reaches the set current, at which time, the first excitation and measurement module 110 controls the value of the driving voltage to stop increasing and remain unchanged.

[0096] In this implementation, the preset value can be zero or other values ​​greater than zero, which is determined by the threshold voltage of the power device DUT to be tested; if the threshold voltage of the power device DUT to be tested is small, the preset value is usually designed to be zero; if the threshold voltage of the power device DUT to be tested is large, the preset value is usually designed to be a value greater than zero, so that the test time can be shortened. In addition, the size of the step value should be set according to actual needs, and there is no restriction on this.

[0097] As an example, the first excitation and measurement module 110 is implemented by SMU, which mainly works in FVMI mode; the fifth switch device K5 is implemented by a gallium nitride device and is controlled by a unified gate control module 140 .

[0098] like Figure 5 As shown, the difference between the test method of this embodiment and the first and second embodiments is that the test method of this embodiment further includes the step of performing a dynamic threshold voltage test on the power device DUT to be tested, including steps S21 to S23; in practical applications, the dynamic threshold voltage test is usually performed after the dynamic on-resistance test. Among them:

[0099] Step S21: before bias is applied, a threshold voltage test is performed on the power device under test DUT.

[0100] Specifically, the method for performing a threshold voltage test on a power device DUT to be tested includes: controlling the fifth switch device K5 to be turned on, short-circuiting the gate terminal and the drain terminal of the power device DUT to be tested, and controlling the first switch device K1 to be turned on, applying a driving voltage to the gate terminal of the power device DUT to be tested through the first excitation and measurement module 110, wherein the driving voltage increases step by step from a preset value; measuring the drain-source current of the power device DUT to be tested through the first excitation and measurement module 110, and stopping the increase of the driving voltage when the drain-source current reaches a set current, so as to obtain the threshold voltage of the power device DUT to be tested based on the current driving voltage; thereafter, controlling the first switch device K1 and the fifth switch device K5 to be turned off.

[0101] Step S22: After the test is completed, a bias is applied to the power device under test DUT; the method of applying the bias in this step is the same as that in step S12 in the first embodiment, and will not be repeated here.

[0102] Step S23: After the bias is applied, a threshold voltage test is performed on the power device under test DUT; the method of the threshold voltage test in this step is the same as that in step S21, and will not be repeated here.

[0103] In this embodiment, the dynamic threshold voltage of the device is characterized based on the difference method, and the threshold voltage of the device measured in step S21 is VTH1, and the threshold voltage of the device measured in step S23 is VTH2, then the dynamic threshold voltage ΔVTH=VTH2-VTH1; the dynamic leakage current of the device is characterized based on the difference method, and the leakage current of the drain end of the device measured in step S12 is IDSS1, and the leakage current of the drain end of the device measured in step S22 is IDSS2, then the dynamic leakage current ΔIDSS=IDSS2-IDSS1. By associating multiple dynamic parameters, failed devices can be screened out more accurately.

[0104] It should be noted that in the test method of this embodiment, step S02 and step S4 are slightly different from those in embodiment 1, and both add a threshold voltage test; for step S02, the threshold voltage test is performed before the on-resistance test; for step S4, the threshold voltage test is performed before the on-resistance test.

[0105] Embodiment 4

[0106] like Figure 6As shown, the difference between this embodiment and the first and second embodiments is that the test circuit 100 also includes a sixth switching device K6, which is connected between the drain and source terminals of the power device DUT to be tested; at this time, the voltage applied to the gate terminal of the power device DUT to be tested by the first excitation and measurement module 110 also includes a bias voltage, and the first excitation and measurement module 110 is also used to measure the gate leakage current of the power device DUT to be tested.

[0107] As an example, the first excitation and measurement module 110 is implemented by SMU, which mainly works in FVMI mode; the sixth switch device K6 is implemented by a gallium nitride device and is controlled by a unified gate control module 140. It should be noted that the bias voltage can be a forward bias voltage or a reverse bias voltage; taking the power device DUT to be tested as a gallium nitride device as an example, the absolute value of the bias voltage is usually less than 10V.

[0108] like Figure 7 As shown, the difference between the test method of this embodiment and the first and second embodiments is that the test method of this embodiment further includes the step of performing a gate leakage test on the power device DUT to be tested.

[0109] The method for performing a gate leakage test on a power device DUT to be tested includes: controlling the sixth switch device K6 to be turned on, short-circuiting the drain and source terminals of the power device DUT to be tested, and controlling the first switch device K1 to be turned on, applying a bias voltage to the gate terminal of the power device DUT to be tested through the first excitation and measurement module 110, and measuring the gate leakage current of the power device DUT to be tested; thereafter, controlling the first switch device K1 and the sixth switch device K6 to be turned off.

[0110] It should be noted that in the testing method of this embodiment, step S02 and step S4 are slightly different from those in embodiment 1, and both add a gate leakage test; for step S02, the gate leakage test is performed before the on-resistance test; for step S4, the gate leakage test is performed before the on-resistance test.

[0111] Embodiment 5

[0112] like Figure 8As shown, the difference between this embodiment and the first and second embodiments is that the test circuit 100 also includes a fifth switch device K5 and a sixth switch device K6, the fifth switch device K5 is connected between the gate terminal and the drain terminal of the power device DUT to be tested, and the sixth switch device K6 is connected between the drain terminal and the source terminal of the power device DUT to be tested; at this time, the voltage applied to the gate terminal of the power device DUT to be tested by the first excitation and measurement module 110 also includes a bias voltage and a step-by-step increasing driving voltage; when the first excitation and measurement module 100 applies a bias voltage to the gate terminal of the power device DUT to be tested, the first excitation and measurement module 110 is also used to measure the gate terminal leakage current of the power device to be tested; when the first excitation and measurement module 110 applies a step-by-step increasing driving voltage to the gate terminal of the power device DUT to be tested, the first excitation and measurement module 110 is also used to measure the drain-source current of the power device DUT to be tested, so as to obtain the threshold voltage of the power device DUT to be tested.

[0113] Specifically, when the first excitation and measurement module 100 applies a bias voltage to the gate terminal of the power device DUT to be tested, the bias voltage may be a forward bias voltage or a reverse bias voltage; taking the power device DUT to be tested as a gallium nitride device as an example, the absolute value of the bias voltage is usually less than 10V.

[0114] When the first excitation and measurement module 110 applies a step-by-step increasing driving voltage to the gate terminal of the power device DUT to be tested, the first excitation and measurement module 110 measures the drain-source current of the power device DUT to be tested, and then compares the drain-source current with the set current, and stops increasing the driving voltage when the drain-source current reaches the set current, so as to obtain the threshold voltage of the power device DUT to be tested based on the current driving voltage, such as using the current driving voltage as the threshold voltage of the power device DUT to be tested. It should be noted that the so-called current driving voltage refers to the voltage value maintained by the driving voltage after stopping the increase.

[0115] In a possible implementation, the first excitation and measurement module 110 controls the value of the driving voltage to increase step by step from a preset value based on the step value. For example, the value of the driving voltage initially output by the first excitation and measurement module 110 is the preset value; after the first comparison, the drain-source current does not reach the set current, and the output driving voltage value is the preset value + the step value; after the second comparison, the drain-source current still does not reach the set current, and the output driving voltage value is the preset value + 2 times the step value; and so on, until the drain-source current reaches the set current, at which time, the first excitation and measurement module 110 controls the value of the driving voltage to stop increasing and remain unchanged.

[0116] In this implementation, the preset value can be zero or other values ​​greater than zero, which is determined by the threshold voltage of the power device DUT to be tested; if the threshold voltage of the power device DUT to be tested is small, the preset value is usually designed to be zero; if the threshold voltage of the power device DUT to be tested is large, the preset value is usually designed to be a value greater than zero, so that the test time can be shortened. In addition, the size of the step value should be set according to actual needs, and there is no restriction on this.

[0117] As an example, the first excitation and measurement module 110 is implemented by SMU, which mainly works in FVMI mode; the fifth switch device K5 and the sixth switch device K6 are implemented by gallium nitride devices and are controlled by a unified gate control module 140 .

[0118] like Fig. 9 As shown, the difference between the testing method of this embodiment and embodiments 1 and 2 is that the testing method of this embodiment also includes: the step of performing a dynamic threshold voltage test on the power device DUT to be tested and the step of performing a gate leakage test on the power device DUT to be tested; in actual applications, the dynamic threshold voltage test is usually performed after the dynamic on-resistance test.

[0119] The method for performing a dynamic threshold voltage test on a power device under test DUT comprises steps S21 to S23. In which:

[0120] Step S21: before bias is applied, a threshold voltage test is performed on the power device under test DUT.

[0121] Specifically, the method for performing a threshold voltage test on a power device DUT to be tested includes: controlling the fifth switch device K5 to be turned on, short-circuiting the gate terminal and the drain terminal of the power device DUT to be tested, and controlling the first switch device K1 to be turned on, applying a driving voltage to the gate terminal of the power device DUT to be tested through the first excitation and measurement module 110, wherein the driving voltage increases step by step from a preset value; measuring the drain-source current of the power device DUT to be tested through the first excitation and measurement module 110, and stopping the increase of the driving voltage when the drain-source current reaches a set current, so as to obtain the threshold voltage of the power device DUT to be tested based on the current driving voltage; thereafter, controlling the first switch device K1 and the fifth switch device K5 to be turned off.

[0122] Step S22: After the test is completed, a bias is applied to the power device under test DUT; the method of applying the bias in this step is the same as that in step S12 in the first embodiment, and will not be repeated here.

[0123] Step S23: After the bias is applied, a threshold voltage test is performed on the power device under test DUT; the method of the threshold voltage test in this step is the same as that in step S21, and will not be repeated here.

[0124] In this embodiment, the dynamic threshold voltage of the device is characterized based on the difference method, and the threshold voltage of the device measured in step S21 is VTH1, and the threshold voltage of the device measured in step S23 is VTH2, then the dynamic threshold voltage ΔVTH=VTH2-VTH1; the dynamic leakage current of the device is characterized based on the difference method, and the leakage current of the drain end of the device measured in step S12 is IDSS1, and the leakage current of the drain end of the device measured in step S22 is IDSS2, then the dynamic leakage current ΔIDSS=IDSS2-IDSS1. By associating multiple dynamic parameters, failed devices can be screened out more accurately.

[0125] The method for performing a gate leakage test on a power device DUT to be tested includes: controlling the sixth switch device K6 to be turned on, short-circuiting the drain and source terminals of the power device DUT to be tested, and controlling the first switch device K1 to be turned on, applying a bias voltage to the gate terminal of the power device DUT to be tested through the first excitation and measurement module 110, and measuring the gate leakage current of the power device DUT to be tested; thereafter, controlling the first switch device K1 and the sixth switch device K6 to be turned off.

[0126] It should be noted that in the testing method of this embodiment, step S02 and step S4 are slightly different from those in embodiment 1, and both add a threshold voltage test and a gate leakage test; for step S02, the gate leakage test is performed before the threshold voltage test, and the threshold voltage test is performed before the on-resistance test; for step S4, the gate leakage test is performed before the threshold voltage test, and the threshold voltage test is performed before the on-resistance test.

[0127] In summary, the test circuit and test method of a power device of the present invention utilizes a high-frequency switch device to complete the rapid switching of the circuit in a very short time, can simulate the effect of a pulse test in the DC test stage, and can realize the test of the dynamic characteristics of the power device without complex pulse testing, which is convenient for screening out failed devices; at the same time, it can also take into account the conventional DC test of the power device, saving test time and cost. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has a high industrial utilization value.

[0128] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A test circuit for a power device, characterized in that: The test circuit comprises: A first excitation and measurement module, a second excitation and measurement module, a third excitation and measurement module, a first switching device, a second switching device and a third switching device; The first end of the first excitation and measurement module is connected to the gate end of the power device to be measured through the first switch device, and the second end is connected to the source end of the power device to be measured, so as to apply a voltage to the gate end of the power device to be measured; The first end of the second excitation and measurement module is connected to the drain end of the power device to be tested through the second switch device, and the second end is connected to the source end of the power device to be tested, and is used to apply a first test current to both ends of the drain and source of the power device to be tested, and measure the drain-source voltage of the power device to be tested to obtain the on-resistance of the power device to be tested; The first end of the third excitation and measurement module is connected to the drain end of the power device to be tested through the third switching device, and the second end is connected to the source end of the power device to be tested, and is used to apply a bias high voltage to both ends of the drain and source of the power device to be tested, and measure the drain leakage current of the power device to be tested.

2. The test circuit according to claim 1, characterized in that: The test circuit also includes: a load resistor and a clamp and measurement module; The load resistor is connected between the third excitation and measurement module and the third switch device, and is used to set a second test current; The clamping and measuring module is connected between the drain-source and source terminals of the power device to be tested, and is used to obtain the on-resistance of the power device to be tested by measuring the drain-source voltage of the power device to be tested when the voltage across the drain-source of the power device to be tested is less than the clamping voltage.

3. The test circuit according to claim 1, characterized in that: The third excitation and measurement module includes: a high-voltage excitation and measurement unit, a fourth switch device and a first capacitor. The high-voltage excitation and measurement unit is connected in series with the fourth switch device and then connected in parallel with the first capacitor. The power device to be measured includes a gallium nitride device.

4. The test circuit according to any one of claims 1 to 3, characterized in that: The test circuit further comprises: a fifth switch device, connected between the gate terminal and the drain terminal of the power device to be tested; at this time, the voltage applied by the first excitation and measurement module to the gate terminal of the power device to be tested includes a step-by-step increasing driving voltage, and the first excitation and measurement module is also used to measure the drain-source current of the power device to be tested to obtain the threshold voltage of the power device to be tested; And / or, a sixth switching device is connected between the drain terminal and the source terminal of the power device to be tested; at this time, the voltage applied to the gate terminal of the power device to be tested by the first excitation and measurement module includes a bias voltage, and the first excitation and measurement module is also used to measure the gate leakage current of the power device to be tested.

5. The test circuit according to claim 4, characterized in that: The first switch device, the second switch device, the third switch device, the fifth switch device and the sixth switch device are implemented by gallium nitride devices; at this time, the test circuit also includes: a gate control module, which is used to control the on and off of each gallium nitride device.

6. A method for testing a power device, characterized in that: Based on the test circuit according to any one of claims 1 to 5, at least a dynamic on-resistance test is performed on the power device to be tested, and the test method comprises: Before bias is applied, performing an on-resistance test on the power device to be tested; After the test is completed, applying a bias to the power device to be tested; After the bias is applied, an on-resistance test is performed on the power device to be tested.

7. The testing method according to claim 6, characterized in that: The method of performing an on-resistance test on the power device to be tested before or after bias is applied includes: Control the first switching device and the second switching device to be turned on, apply a turn-on voltage to the gate terminal of the power device to be tested through the first excitation and measurement module to put the power device to be tested in a turn-on state, apply a first test current to the drain-source terminals of the power device to be tested through the second excitation and measurement module, and measure the drain-source voltage of the power device to be tested to obtain the on-resistance of the power device to be tested.

8. The testing method according to claim 6, characterized in that: The method of applying bias to the power device to be tested comprises: Control the first switching device and the third switching device to be turned on, apply zero voltage to the gate terminal of the power device to be tested through the first excitation and measurement module, apply bias high voltage to the drain-source terminals of the power device to be tested through the third excitation and measurement module, and measure the drain leakage current of the power device to be tested.

9. The testing method according to claim 8, characterized in that: When the test circuit includes a load resistor and a clamp and measurement module, after bias is applied, the method for performing an on-resistance test on the power device to be tested includes: Keep the first switching device and the third switching device turned on, apply a turn-on voltage to the gate terminal of the power device to be tested through the first excitation and measurement module to turn on the power device to be tested, and measure the drain-source voltage of the power device to be tested through the clamping and measurement module to obtain the on-resistance of the power device to be tested.

10. The testing method according to claim 6, characterized in that: When the test circuit includes a fifth switch device, the test method further includes: a step of performing a dynamic threshold voltage test on the power device to be tested; And / or, when the test circuit includes a sixth switching device, the test method further includes: a step of performing a gate leakage test on the power device to be tested.

11. The testing method according to claim 10, characterized in that: The method for performing a dynamic threshold voltage test on the power device to be tested comprises: Before bias is applied, a threshold voltage test is performed on the power device to be tested; After the test is completed, applying a bias to the power device to be tested; After the bias is applied, a threshold voltage test is performed on the power device to be tested.

12. The testing method according to claim 11, characterized in that: The method of performing a threshold voltage test on the power device to be tested before or after bias is applied includes: Controlling the fifth switch device to be turned on, short-circuiting the gate terminal and the drain terminal of the power device to be tested, and controlling the first switch device to be turned on, applying a driving voltage to the gate terminal of the power device to be tested through the first excitation and measurement module, wherein the driving voltage increases step by step from a preset value; measuring the drain-source current of the power device to be tested through the first excitation and measurement module, and stopping the increase of the driving voltage when the drain-source current reaches a set current, so as to obtain the threshold voltage of the power device to be tested based on the current driving voltage; The method of applying bias to the power device to be tested comprises: Control the first switching device and the third switching device to be turned on, apply zero voltage to the gate terminal of the power device to be tested through the first excitation and measurement module, apply bias high voltage to the drain-source terminals of the power device to be tested through the third excitation and measurement module, and measure the drain leakage current of the power device to be tested.

13. The testing method according to claim 10, characterized in that: The method for performing a gate leakage test on the power device to be tested comprises: The sixth switch device is controlled to be turned on, the drain and source terminals of the power device to be tested are short-circuited, and the first switch device is controlled to be turned on, a bias voltage is applied to the gate terminal of the power device to be tested through the first excitation and measurement module, and the gate leakage current of the power device to be tested is measured.

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