Bipolar degradation screening method, device and system for silicon carbide device

Abstract

The invention relates to a bipolar degradation screening method, device and system for a silicon carbide device. The bipolar degradation screening method comprises the following steps: performing a direct-current stress test on a to-be-tested silicon carbide device to obtain a first test result; under the condition that the first test result is unqualified, determining that the bipolar degradation screening result of the silicon carbide device to be tested is unqualified; under the condition that the first test result is qualified, performing a pulse stress test on the silicon carbide device to be tested to obtain a second test result; and determining a bipolar degradation screening result of the silicon carbide device to be tested according to the second test result. By adopting the bipolar degradation screening method provided by the invention, rapid screening of the silicon carbide device with a bipolar degradation phenomenon can be realized.

Description

Technical Field

[0001] The present application relates to the technical field of silicon carbide device testing, and in particular to a bipolar degradation screening method, device and system for silicon carbide devices. Background Art

[0002] In silicon carbide devices, the phenomenon of the body diode's on-state voltage drop and the device's forward resistance increasing over time is called bipolar degradation. Bipolar degradation is primarily triggered by defects in the SiC crystal. When current flows through the body diode, the energy released by the recombination of electrons and holes induces stacking faults (SFs) to propagate along basal plane dislocations (BPDs). These SFs stop propagating until they reach the chip surface, at which point bipolar degradation reaches saturation.

[0003] Devices from different manufacturers experience different rates of bipolar degradation under DC and pulse conditions. For some manufacturers' devices, pulse stress may accelerate bipolar degradation more than DC stress, while for other manufacturers' devices, DC stress accelerates bipolar degradation more than pulse stress. If it is unknown which condition degrades faster, using a single condition for bipolar degradation screening may increase screening time and damage the device. Summary of the Invention

[0004] Based on this, it is necessary to provide a bipolar degradation screening method, device and system for silicon carbide devices that can achieve rapid screening.

[0005] In a first aspect, the present application provides a bipolar degradation screening method for a silicon carbide device, comprising:

[0006] Performing a DC stress test on the silicon carbide device to be tested to obtain a first test result;

[0007] In a case where the first test result is unqualified, determining that the bipolar degradation screening result of the silicon carbide device to be tested is unqualified;

[0008] If the first test result is qualified, performing a pulse stress test on the silicon carbide device to be tested to obtain a second test result;

[0009] According to the second test result, a bipolar degradation screening result of the silicon carbide device to be tested is determined.

[0010] In one embodiment, performing a DC stress test on the silicon carbide device to be tested to obtain a first test result includes:

[0011] Obtaining initial electrical parameters of the silicon carbide device to be tested;

[0012] Applying a drive signal to the gate of the silicon carbide device to be tested, and applying a DC voltage to the first electrode and the second electrode of the silicon carbide device to be tested, so as to apply a DC stress to the silicon carbide device to be tested; the drive signal is used to put the silicon carbide device to be tested in an off state;

[0013] Obtaining a first degradation electrical parameter of the silicon carbide device to be tested under the DC stress;

[0014] The first test result is determined according to the initial electrical parameter and the first degraded electrical parameter.

[0015] In one embodiment, performing a pulse stress test on the silicon carbide device to be tested to obtain a second test result includes:

[0016] Obtaining initial electrical parameters of the silicon carbide device to be tested;

[0017] Applying a driving signal to the gate of the silicon carbide device to be tested, and applying a pulse voltage to the first electrode and the second electrode of the silicon carbide device to be tested, so as to apply a pulse stress to the silicon carbide device to be tested; the driving signal is used to put the silicon carbide device in an off state;

[0018] Obtaining a second degradation electrical parameter of the silicon carbide device to be tested under the pulse stress;

[0019] The second test result is determined according to the initial electrical parameter and the second degraded electrical parameter.

[0020] In one embodiment, the method further comprises:

[0021] Obtaining a first temperature of the silicon carbide device to be tested during the DC stress test, and / or obtaining a second temperature of the silicon carbide device to be tested during the pulse stress test;

[0022] In a case where the first test result is unqualified, determining a bipolar degradation screening result of the silicon carbide device to be tested according to the first temperature and the first test result;

[0023] Determining the bipolar degradation screening result of the silicon carbide device to be tested according to the second test result includes:

[0024] A bipolar degradation screening result of the silicon carbide device to be tested is determined according to the second temperature and the second test result.

[0025] In a second aspect, the present application further provides a bipolar degradation screening device for a silicon carbide device, comprising:

[0026] A DC test module, used for performing a DC stress test on at least one silicon carbide device to be tested;

[0027] A pulse test module, used for performing a pulse stress test on the silicon carbide device to be tested;

[0028] A monitoring module is used to obtain a first test result, and when the first test result is unqualified, determine that the bipolar degradation screening result of the silicon carbide device to be tested is unqualified; and when the first test result is qualified, control the pulse test module to perform a pulse stress test on the silicon carbide device to be tested, obtain a second test result, and determine the bipolar degradation screening result of the silicon carbide device to be tested based on the second test result.

[0029] In one embodiment, the DC test module includes:

[0030] a first power supply, connected to the first electrode and the second electrode of the silicon carbide device to be tested, respectively, for providing a DC voltage to the first electrode and the second electrode of the silicon carbide device to be tested, so as to apply a DC stress to the silicon carbide device to be tested;

[0031] a first driving circuit connected to the gate of the silicon carbide device to be tested, and configured to provide a driving signal to the gate of the silicon carbide device to be tested, wherein the driving signal is configured to turn off the silicon carbide device to be tested;

[0032] The monitoring module is also used to obtain the initial electrical parameters of the silicon carbide device to be tested, and detect the first degradation electrical parameters of the silicon carbide device to be tested under the DC stress, and determine the first test result based on the initial electrical parameters and the first degradation electrical parameters.

[0033] In one embodiment, the pulse test module includes:

[0034] a second power supply, connected to the first electrode of the silicon carbide device to be tested, and configured to provide a DC voltage;

[0035] a switch assembly, connected to the second power supply and the second electrode of the silicon carbide device to be tested, respectively, for converting the DC voltage into a pulse voltage, and outputting the pulse voltage to the second electrode of the silicon carbide device to be tested, so as to apply pulse stress to the silicon carbide device to be tested;

[0036] a second driving circuit, connected to the gate of the silicon carbide device to be tested, and configured to provide a driving signal to the gate of the silicon carbide device to be tested, wherein the driving signal is configured to turn off the silicon carbide device to be tested;

[0037] The monitoring module is also used to obtain the initial electrical parameters of the silicon carbide device to be tested, and detect the second degradation electrical parameters of the silicon carbide device to be tested under the pulse stress, and determine the second test result based on the initial electrical parameters and the second degradation electrical parameters.

[0038] In one embodiment, there are multiple silicon carbide devices to be tested, and the multiple silicon carbide devices to be tested are connected in series.

[0039] In one embodiment, the monitoring module is further used to obtain a first temperature of the silicon carbide device to be tested during the DC stress test, and when the first test result is unqualified, determine a bipolar degradation screening result of the silicon carbide device to be tested based on the first temperature and the first test result;

[0040] The monitoring module is also used to obtain the second temperature of the silicon carbide device to be tested during the pulse stress test when the first test result is qualified, and determine the bipolar degradation screening result of the silicon carbide device to be tested based on the second temperature and the second test result.

[0041] In a third aspect, the present application further provides a bipolar degradation screening system for silicon carbide devices, comprising a silicon carbide device to be tested and a bipolar degradation screening apparatus for silicon carbide devices provided by any of the above embodiments.

[0042] In the above-mentioned bipolar degradation screening method, apparatus, and system for silicon carbide devices, a DC stress test is performed on the silicon carbide device to be tested to obtain a first test result. If the first test result is unqualified, the bipolar degradation screening result of the silicon carbide device to be tested is determined to be unqualified, and preliminary screening of silicon carbide devices with high BPD density is performed. Since the bipolar degradation rate of silicon carbide devices with higher BPD density is faster when DC stress is applied than when pulse stress is applied, test time can be saved. Furthermore, if the first test result is qualified, a pulse stress test is performed on the silicon carbide device to be tested to obtain a second test result. Based on the second test result, the bipolar degradation screening result of the silicon carbide device to be tested is determined. Since the bipolar degradation rate of silicon carbide devices with low BPD density is faster when pulse stress is applied than when DC stress is applied, the total time required for performing the DC stress test and the pulse stress test is much shorter than the time required for performing only the DC stress test, further saving test time and achieving rapid screening of silicon carbide devices with bipolar degradation. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the conventional technology, the following briefly introduces the drawings required for use in the embodiments or the conventional technology descriptions. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0044] Figure 1 A flow chart of a bipolar degradation screening method for a silicon carbide device provided in one embodiment;

[0045] Figure 2 A flow chart of performing a DC stress test on a silicon carbide device to be tested and obtaining a first test result in a bipolar degradation screening method for a silicon carbide device provided in one embodiment;

[0046] Figure 3 A flow chart of performing a pulse stress test on a silicon carbide device to be tested and obtaining a second test result in a bipolar degradation screening method for a silicon carbide device provided in one embodiment;

[0047] Figure 4 A flowchart of a bipolar degradation screening method for a silicon carbide device provided in a specific embodiment;

[0048] Figure 5 A structural block diagram of a bipolar degradation screening device for a silicon carbide device provided in one embodiment;

[0049] Figure 6 A structural block diagram of a DC test module provided in one embodiment;

[0050] Figure 7 A structural block diagram of a pulse test module provided in one embodiment;

[0051] Figure 8 A structural block diagram of a DC test module provided in another embodiment;

[0052] Figure 9 A structural block diagram of a pulse test module provided in another embodiment. DETAILED DESCRIPTION

[0053] To facilitate understanding of the present application, the present application will be described more fully below with reference to the accompanying drawings. The accompanying drawings provide embodiments of the present application. However, the present application may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to make the disclosure of the present application more thorough and comprehensive.

[0054] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0055] It can be understood that the “connection” in the following embodiments should be understood as “electrical connection”, “communication connection”, etc. if there is transmission of electrical signals or data between the connected circuits, modules, units, etc.

[0056] It is understood that “at least one” refers to one or more, “a plurality” refers to two or more, and “at least a portion of an element” refers to a portion or all of an element.

[0057] As used herein, the singular forms "a," "an," and "the" may also include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include," "comprising," "having," and the like specify the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof. Furthermore, the term "and / or" as used in this specification includes any and all combinations of the relevant listed items.

[0058] In one embodiment, Figure 1 As shown, the present application provides a bipolar degradation screening method for silicon carbide devices, including steps S102-S108.

[0059] S102: Perform a DC stress test on the silicon carbide device to be tested to obtain a first test result.

[0060] The DC stress test refers to applying DC stress to the body diode of the silicon carbide device to be tested to detect whether bipolar degradation occurs, for example, whether the forward voltage drop of the body diode and the forward resistance of the device are significantly increased. The first test results include qualified and unqualified. After the DC stress test is performed on the silicon carbide device to be tested, if bipolar degradation occurs in the silicon carbide device to be tested, the first test result is unqualified. If no bipolar degradation occurs in the silicon carbide device to be tested, the first test result is qualified. For example, the test duration of the DC stress test can be 24 hours.

[0061] The bipolar degradation rate varies across devices, and this phenomenon is related to the epitaxial growth process. For SiC devices with a higher BPD density, the bipolar degradation rate is faster when DC stress is applied than when pulse stress is applied. When the epitaxial growth process is poor, the BPD density in the drift layer of the SiC device is high. Applying DC stress to the SiC device causes electrons and holes to be continuously injected into the drift layer, resulting in enhanced carrier recombination near the BPDs and promoting dislocation slip and expansion. Furthermore, at high BPD density, multiple dislocations are simultaneously impacted by carriers, significantly accelerating the degradation rate. Furthermore, the DC stress is continuous, and the continuous accumulation of Joule heat in the device causes a local temperature increase, further accelerating dislocation expansion.

[0062] S104 , when the first test result is unqualified, determining that the bipolar degradation screening result of the silicon carbide device to be tested is unqualified.

[0063] S106 , when the first test result is qualified, performing a pulse stress test on the silicon carbide device to be tested to obtain a second test result.

[0064] Pulse stress testing involves applying pulse stress to the body diode of a SiC device under test to detect bipolar degradation. When DC stress is applied to a SiC device with a low BPD concentration in the drift layer, the recombination energy after carrier injection is dispersed, making it difficult to form large-scale stacking faults (SFs). While there is sustained heating under DC stress, the small number of BPDs limits the propagation of dislocation slip, making it difficult to detect bipolar degradation within a short test time. When pulse stress is applied to a SiC device with a low BPD concentration in the drift layer, the transient current density under pulse stress is far higher than the device's rated current. The high peak current causes a sharp increase in the local carrier concentration, resulting in higher carrier recombination energy around a single dislocation, which accelerates dislocation propagation. Furthermore, the rising and falling edges of the pulse generate transient temperature gradients near the BPDs, further promoting dislocation slip. Therefore, for SiC devices with low BPD density, the bipolar degradation rate under pulse stress is faster than that under DC stress.

[0065] The second test result can be either qualified or unqualified. After the pulse stress test on the silicon carbide device under test, if bipolar degradation occurs in the silicon carbide device under test, the second test result is unqualified. If no bipolar degradation occurs in the silicon carbide device under test, the second test result is qualified. For example, the pulse stress test can last for 24 hours.

[0066] S108 , determining a bipolar degradation screening result of the silicon carbide device to be tested according to the second test result.

[0067] If the second test result is qualified, the bipolar degradation screening result of the silicon carbide device to be tested is determined to be qualified; if the second test result is unqualified, the bipolar degradation screening result of the silicon carbide device to be tested is determined to be unqualified.

[0068] In an embodiment of the present application, a DC stress test is performed on the silicon carbide device to be tested to obtain a first test result. If the first test result is unqualified, the bipolar degradation screening result of the silicon carbide device to be tested is determined to be unqualified, and a preliminary screening of silicon carbide devices with high BPD density is performed. Since the bipolar degradation rate when DC stress is applied is faster than the bipolar degradation rate when pulse stress is applied for silicon carbide devices with higher BPD density, test time can be saved. Furthermore, if the first test result is qualified, a pulse stress test is performed on the silicon carbide device to be tested to obtain a second test result. Based on the second test result, a bipolar degradation screening result of the silicon carbide device to be tested is determined. Since the bipolar degradation rate when pulse stress is applied is faster than the bipolar degradation rate when DC stress is applied for silicon carbide devices with low BPD density, the total time required for performing the DC stress test and the pulse stress test is much less than the time required for performing only the DC stress test, further saving test time and achieving rapid screening of silicon carbide devices with bipolar degradation.

[0069] In one embodiment, Figure 2 As shown, a DC stress test is performed on the silicon carbide device to be tested to obtain a first test result, including steps S202-S208.

[0070] S202: Obtain initial electrical parameters of the silicon carbide device to be tested.

[0071] For example, the initial electrical parameters may include an initial voltage drop of a body diode, an initial on-resistance of a silicon carbide device, and other electrical parameters.

[0072] S204 , applying a driving signal to the gate of the silicon carbide device to be tested, and applying a DC voltage to the first electrode and the second electrode of the silicon carbide device to be tested, so as to apply a DC stress to the silicon carbide device to be tested.

[0073] The driving signal is used to turn off the silicon carbide device under test. The DC voltage may be approximately the rated voltage of the silicon carbide device.

[0074] S206: Obtain a first degradation electrical parameter of the silicon carbide device to be tested under DC stress.

[0075] For example, the first degradation electrical parameter may include a real-time voltage drop of a body diode under DC stress, and an on-resistance of the silicon carbide device after a DC stress test.

[0076] S208 : Determine a first test result according to the initial electrical parameter and the first degraded electrical parameter.

[0077] After the DC stress test, the difference between the first degraded electrical parameter and the initial electrical parameter can be calculated. If the difference exceeds a preset value, the silicon carbide device under test is considered to have bipolar degradation and the first test result is considered unqualified. If the difference does not exceed the preset value, the first test result is considered qualified. Different preset values ​​correspond to different parameters and can be reasonably set based on the actual operating characteristics of the device, without any limitation here.

[0078] In this embodiment, by obtaining initial electrical parameters of the silicon carbide device to be tested, applying a drive signal to the gate of the silicon carbide device to be tested to put the silicon carbide device to be tested into an off state, applying a DC voltage to the first electrode and the second electrode of the silicon carbide device to be tested to apply DC stress to the silicon carbide device to be tested, obtaining first degradation electrical parameters of the silicon carbide device to be tested under DC stress, and determining a first test result based on the initial electrical parameters and the first degradation electrical parameters, a DC stress test of the silicon carbide device to be tested is implemented. Silicon carbide devices with bipolar degradation can be preliminarily screened based on the first test result.

[0079] In one embodiment, Figure 3 As shown, a pulse stress test is performed on the silicon carbide device to be tested to obtain a second test result, including steps S302-S308.

[0080] S302: Obtain initial electrical parameters of the silicon carbide device to be tested.

[0081] S304 , applying a driving signal to the gate of the silicon carbide device to be tested, and applying a pulse voltage to the first electrode and the second electrode of the silicon carbide device to be tested, so as to apply a pulse stress to the silicon carbide device to be tested.

[0082] The driving signal is used to turn off the silicon carbide device. For example, the pulse voltage may be three times the rated voltage.

[0083] S306 , obtaining a second degradation electrical parameter of the silicon carbide device to be tested under pulse stress.

[0084] For example, the second degradation electrical parameter may include a real-time voltage drop of a body diode under pulse stress, and an on-resistance of the silicon carbide device after a pulse stress test.

[0085] S308 : Determine a second test result according to the initial electrical parameter and the second degraded electrical parameter.

[0086] After the pulse stress test, the difference between the second degraded electrical parameter and the initial electrical parameter can be calculated. If the difference exceeds a preset value, the silicon carbide device under test is considered to have bipolar degradation and the second test result is considered unqualified. If the difference does not exceed the preset value, the second test result is qualified. Different parameters correspond to different preset values, and the preset values ​​can be reasonably set based on the actual operating characteristics of the device, without any limitation here.

[0087] In one embodiment, the bipolar degradation screening method for silicon carbide devices further includes obtaining a first temperature of the silicon carbide device to be tested during a DC stress test, and determining a bipolar degradation screening result of the silicon carbide device to be tested based on the first temperature and the first test result when the first test result is unqualified.

[0088] Thermal effects can accelerate the aging of the SiC device under test, increasing its on-resistance. Therefore, when performing bipolar degradation screening, it is necessary to eliminate the interference of thermal effects. Therefore, it is necessary to obtain the first temperature of the SiC device under test during the DC stress test. If the first test result is unqualified and the first temperature does not exceed the preset temperature range, the bipolar degradation screening result of the SiC device under test is determined to be unqualified.

[0089] In one embodiment, the bipolar degradation screening method for silicon carbide devices further includes obtaining a first temperature of the silicon carbide device to be tested during a DC stress test, and if the first test result is qualified, obtaining a second temperature of the silicon carbide device to be tested during a pulse stress test, and determining a bipolar degradation screening result of the silicon carbide device to be tested based on the second temperature and the second test result.

[0090] It can be understood that the second temperature of the silicon carbide device to be tested during the pulse stress test is obtained. When the second test result is unqualified and the second temperature does not exceed the preset temperature range, the bipolar degradation screening result of the silicon carbide device to be tested is determined to be unqualified; when the second test result is unqualified and the second temperature exceeds the preset temperature range, the silicon carbide device to be tested can be marked, and it cannot be determined whether the phenomenon is caused by thermal effects or bipolar degradation; when the second test result is qualified, the bipolar degradation screening result of the silicon carbide device to be tested is determined to be qualified.

[0091] In order to better illustrate the bipolar degradation screening method of the silicon carbide device of the present application, a more specific embodiment is given. Figure 4As shown, the initial electrical parameters of the silicon carbide device under test are first obtained, including the initial voltage drop of the body diode and the initial on-resistance of the device. A DC stress is applied to the silicon carbide device under test for 24 hours, and the first voltage drop of the body diode and the first on-resistance of the silicon carbide device after the DC stress are applied are measured. If the first voltage drop is significantly increased compared to the initial voltage drop, and the first on-resistance is significantly increased compared to the initial on-resistance, bipolar degradation is determined to be present, and the silicon carbide device under test fails. If the first voltage drop or the first on-resistance does not significantly increase, a pulse stress of 3 times the rated current is applied to the silicon carbide device under test for 24 hours, and the second voltage drop of the body diode and the second on-resistance of the silicon carbide device after the pulse stress are measured. If the second voltage drop is significantly increased compared to the initial voltage drop, and the second on-resistance is significantly increased compared to the initial on-resistance, bipolar degradation is determined to be present, and the silicon carbide device under test fails. If the second voltage drop or the second on-resistance does not significantly increase, bipolar degradation is not present, and the silicon carbide device under test passes.

[0092] Based on the same inventive concept, in one embodiment, Figure 5 As shown, the present application also provides a bipolar degradation screening device for silicon carbide devices, including a DC test module 502 , a pulse test module 504 and a monitoring module 506 .

[0093] The DC test module 502 is used to perform a DC stress test on at least one silicon carbide device to be tested.

[0094] The pulse test module 504 is used to perform a pulse stress test on the silicon carbide device to be tested.

[0095] The monitoring module 506 may include a voltage detection circuit, an oscilloscope, an analyzer, and the like. The monitoring module 506 may be connected to the first and second electrodes of the silicon carbide device to be tested, respectively. The monitoring module 506 is configured to obtain a first test result, and if the first test result is unqualified, determine that the bipolar degradation screening result of the silicon carbide device to be tested is unqualified. If the first test result is qualified, the monitoring module 506 controls the pulse test module 504 to perform a pulse stress test on the silicon carbide device to be tested, obtain a second test result, and determine the bipolar degradation screening result of the silicon carbide device to be tested based on the second test result.

[0096] The specific description of the functions of each module can be found in the description of the bipolar degradation screening method for silicon carbide devices provided in the above embodiments, and will not be repeated here.

[0097] In this embodiment, a DC stress test is performed on at least one silicon carbide device to be tested by the DC test module 502, and a first test result is obtained by the monitoring module 506. If the first test result is unqualified, the bipolar degradation screening result of the silicon carbide device to be tested is determined to be unqualified, and a preliminary screening is performed on silicon carbide devices with high BPD density. Since the bipolar degradation rate of silicon carbide devices with high BPD density when DC stress is applied is faster than the bipolar degradation rate when pulse stress is applied, test time can be saved. Furthermore, if the first test result is qualified, the monitoring module 506 The controllable pulse test module 504 performs a pulse stress test on the silicon carbide device to be tested. Afterwards, the monitoring module 506 obtains a second test result and determines the bipolar degradation screening result of the silicon carbide device to be tested based on the second test result. Since the bipolar degradation rate of silicon carbide devices with low-density BPD when pulse stress is applied is faster than the bipolar degradation rate when DC stress is applied, the total time required for DC stress testing and pulse stress testing is much shorter than the time required for only DC stress testing, which further saves test time and realizes rapid screening of silicon carbide devices with bipolar degradation.

[0098] In one embodiment, Figure 6 As shown, the DC test module includes a first power supply 602 and a first drive circuit 604 .

[0099] The first power supply 602 is connected to the first electrode and the second electrode of the silicon carbide device under test, respectively, and is used to provide a DC voltage to the first electrode and the second electrode of the silicon carbide device under test to apply a DC stress to the silicon carbide device under test. The first power supply 602 can be a constant voltage source.

[0100] The first driving circuit 604 is connected to the gate of the silicon carbide device under test, and is used to provide a driving signal to the gate of the silicon carbide device under test, and the driving signal is used to put the silicon carbide device under test into an off state.

[0101] The monitoring module 506 is further configured to obtain initial electrical parameters of the silicon carbide device under test, detect first degraded electrical parameters of the silicon carbide device under test under DC stress, and determine a first test result based on the initial electrical parameters and the first degraded electrical parameters.

[0102] In one embodiment, Figure 6 As shown, the DC test module may further include a capacitor C1 and a diode D1. The diode D1 is used to ensure unidirectional flow of electrical signals on the line. The capacitor C1 is connected in parallel with the first power supply 602 to smooth ripples.

[0103] In one embodiment, the DC test module further includes a first heat dissipation component. For example, the first heat dissipation component may be a cooling fan, a water-cooling plate, or the like.

[0104] In one embodiment, Figure 7 As shown, the pulse test module includes a second power supply 702 , a switch component and a second drive circuit 706 .

[0105] The second power supply 702 is connected to the first electrode of the silicon carbide device to be tested and is used to provide a DC voltage. The second power supply 702 is a constant voltage source.

[0106] The switch assembly is connected to the second power supply and the second terminal of the silicon carbide device under test, respectively, and is configured to convert a DC voltage into a pulse voltage and output the pulse voltage to the second terminal of the silicon carbide device under test to apply a pulse stress to the silicon carbide device under test. The switch assembly includes a switch tube K and a switch tube drive circuit 7042. The switch tube drive circuit 7042 is connected to the gate of the switch tube K and is configured to drive the switch tube K to periodically conduct.

[0107] The second driving circuit 706 is connected to the gate of the silicon carbide device under test, and is used to provide a driving signal to the gate of the silicon carbide device under test, and the driving signal is used to turn off the silicon carbide device under test.

[0108] The monitoring module 506 is further configured to obtain initial electrical parameters of the silicon carbide device under test, detect second degraded electrical parameters of the silicon carbide device under test under pulse stress, and determine a second test result based on the initial electrical parameters and the second degraded electrical parameters.

[0109] In one embodiment, Figure 7 As shown, the pulse test module may further include a capacitor C2 and a diode D2. The diode D2 is used to ensure unidirectional flow of electrical signals on the line. The capacitor C2 is connected in parallel with the second power supply 702 to smooth ripples.

[0110] In one embodiment, the pulse test module further includes a second heat dissipation component. For example, the second heat dissipation component may be a cooling fan, a heat sink, or the like.

[0111] In one embodiment, there are multiple silicon carbide devices to be tested, and the multiple silicon carbide devices to be tested are connected in series. For example, Figure 8-Figure 9 As shown, the number of silicon carbide devices to be tested is 3, wherein the first electrode of the second silicon carbide device to be tested DUT2 is connected to the second electrode of the first silicon carbide device to be tested DUT1, and the second electrode of the second silicon carbide device to be tested DUT2 is connected to the first electrode of the third silicon carbide device to be tested DUT3. Figure 8 As shown, when performing a DC stress test, the first power supply 602 is connected to the first electrode of the first silicon carbide device under test DUT1 and the second electrode of the third silicon carbide device under test DUT3 respectively. Each silicon carbide device under test is provided with a first driving circuit 604, and the monitoring module is connected to the first electrode and the second electrode of each silicon carbide device under test respectively. Figure 9As shown, when performing a pulse stress test, the second power supply 702 is connected to the first pole of the first silicon carbide device to be tested DUT1, the switch component is connected to the second pole of the third silicon carbide device to be tested DUT3, each silicon carbide device to be tested is respectively provided with a second driving circuit 706, and the monitoring module is respectively connected to the first pole and the second pole of each silicon carbide device to be tested.

[0112] In one embodiment, the monitoring module is further configured to obtain a first temperature of the silicon carbide device under test during a DC stress test. For example, the monitoring module may include a thermocouple, which may be attached to a housing of the silicon carbide device under test. The first temperature may be determined by the resistance of the thermocouple during the DC stress test. The monitoring module is further configured to determine a bipolar degradation screening result for the silicon carbide device under test based on the first temperature and the first test result if the first test result is unqualified.

[0113] The monitoring module is also used to obtain the second temperature of the silicon carbide device to be tested during the pulse stress test when the first test result is qualified. For example, the second temperature can be determined by the resistance value of the thermocouple during the pulse stress test. Furthermore, the monitoring module can determine the bipolar degradation screening result of the silicon carbide device to be tested based on the second temperature and the second test result.

[0114] In one embodiment, the present application further provides a bipolar degradation screening system for silicon carbide devices, comprising a silicon carbide device to be tested and the bipolar degradation screening apparatus for silicon carbide devices provided by any of the above embodiments.

[0115] In the description of this specification, reference to the terms "some embodiments" or "other embodiments" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example.

[0116] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0117] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be determined by the appended claims.

Claims

1. A bipolar degradation screening method for silicon carbide devices, characterized in that: include: Performing a DC stress test on the silicon carbide device to be tested to obtain a first test result; In a case where the first test result is unqualified, determining that the bipolar degradation screening result of the silicon carbide device to be tested is unqualified; If the first test result is qualified, performing a pulse stress test on the silicon carbide device to be tested to obtain a second test result; According to the second test result, a bipolar degradation screening result of the silicon carbide device to be tested is determined.

2. The method according to claim 1, characterized in that The performing a DC stress test on the silicon carbide device to be tested to obtain a first test result includes: Obtaining initial electrical parameters of the silicon carbide device to be tested; Applying a drive signal to the gate of the silicon carbide device to be tested, and applying a DC voltage to the first electrode and the second electrode of the silicon carbide device to be tested, so as to apply a DC stress to the silicon carbide device to be tested; the drive signal is used to put the silicon carbide device to be tested in an off state; Obtaining a first degradation electrical parameter of the silicon carbide device to be tested under the DC stress; The first test result is determined according to the initial electrical parameter and the first degraded electrical parameter.

3. The method according to claim 1, characterized in that The performing a pulse stress test on the silicon carbide device to be tested to obtain a second test result includes: Obtaining initial electrical parameters of the silicon carbide device to be tested; Applying a driving signal to the gate of the silicon carbide device to be tested, and applying a pulse voltage to the first electrode and the second electrode of the silicon carbide device to be tested, so as to apply a pulse stress to the silicon carbide device to be tested; the driving signal is used to put the silicon carbide device in an off state; Obtaining a second degradation electrical parameter of the silicon carbide device to be tested under the pulse stress; The second test result is determined according to the initial electrical parameter and the second degraded electrical parameter.

4. The method according to any one of claims 1 to 3, characterized in that The method further comprises: Obtaining a first temperature of the silicon carbide device to be tested during the DC stress test, and / or obtaining a second temperature of the silicon carbide device to be tested during the pulse stress test; In a case where the first test result is unqualified, determining a bipolar degradation screening result of the silicon carbide device to be tested according to the first temperature and the first test result; Determining the bipolar degradation screening result of the silicon carbide device to be tested according to the second test result includes: A bipolar degradation screening result of the silicon carbide device to be tested is determined according to the second temperature and the second test result.

5. A bipolar degradation screening device for silicon carbide devices, characterized in that: include: A DC test module, used for performing a DC stress test on at least one silicon carbide device to be tested; A pulse test module, used for performing a pulse stress test on the silicon carbide device to be tested; A monitoring module is used to obtain a first test result, and when the first test result is unqualified, determine that the bipolar degradation screening result of the silicon carbide device to be tested is unqualified; and when the first test result is qualified, control the pulse test module to perform a pulse stress test on the silicon carbide device to be tested, obtain a second test result, and determine the bipolar degradation screening result of the silicon carbide device to be tested based on the second test result.

6. The bipolar degradation screening device for silicon carbide devices according to claim 5, characterized in that: The DC test module includes: a first power supply, connected to the first electrode and the second electrode of the silicon carbide device to be tested, respectively, for providing a DC voltage to the first electrode and the second electrode of the silicon carbide device to be tested, so as to apply a DC stress to the silicon carbide device to be tested; a first driving circuit connected to the gate of the silicon carbide device to be tested, and configured to provide a driving signal to the gate of the silicon carbide device to be tested, wherein the driving signal is configured to turn off the silicon carbide device to be tested; The monitoring module is also used to obtain the initial electrical parameters of the silicon carbide device to be tested, and detect the first degradation electrical parameters of the silicon carbide device to be tested under the DC stress, and determine the first test result based on the initial electrical parameters and the first degradation electrical parameters.

7. The bipolar degradation screening device for silicon carbide devices according to claim 5, characterized in that: The pulse test module includes: a second power supply, connected to the first electrode of the silicon carbide device to be tested, and configured to provide a DC voltage; a switch assembly, connected to the second power supply and the second electrode of the silicon carbide device to be tested, respectively, for converting the DC voltage into a pulse voltage, and outputting the pulse voltage to the second electrode of the silicon carbide device to be tested, so as to apply pulse stress to the silicon carbide device to be tested; a second driving circuit, connected to the gate of the silicon carbide device to be tested, and configured to provide a driving signal to the gate of the silicon carbide device to be tested, wherein the driving signal is configured to turn off the silicon carbide device to be tested; The monitoring module is also used to obtain the initial electrical parameters of the silicon carbide device to be tested, and detect the second degradation electrical parameters of the silicon carbide device to be tested under the pulse stress, and determine the second test result based on the initial electrical parameters and the second degradation electrical parameters.

8. The bipolar degradation screening device for silicon carbide devices according to claim 5, characterized in that: There are multiple silicon carbide devices to be tested, and the multiple silicon carbide devices to be tested are connected in series.

9. The bipolar degradation screening device for silicon carbide devices according to claim 5, characterized in that: The monitoring module is further configured to obtain a first temperature of the silicon carbide device to be tested during the DC stress test, and determine a bipolar degradation screening result of the silicon carbide device to be tested based on the first temperature and the first test result when the first test result is unqualified; The monitoring module is also used to obtain the second temperature of the silicon carbide device to be tested during the pulse stress test when the first test result is qualified, and determine the bipolar degradation screening result of the silicon carbide device to be tested based on the second temperature and the second test result.

10. A bipolar degradation screening system for silicon carbide devices, characterized in that: A bipolar degradation screening device comprising a silicon carbide device to be tested and the silicon carbide device according to any one of claims 5 to 9.

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