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

Abstract

The present application provides a bipolar degradation test method, silicon carbide device and system for a silicon carbide device. The initial pulse current applied to the target silicon carbide device for the first time is a preset pulse current corresponding to the specification of the target silicon carbide device, so that the initial pulse current applied to the target silicon carbide device for the first time is more in line with the actual working condition. The target silicon carbide device is subjected to a bipolar degradation test using a second flow time and a maximum pulse current, and is allowed to stand after the test. After the standing, whether the target silicon carbide device has failed is determined based on the size of a first static characteristic indicator. Compared with the existing scheme, the determination of whether the target silicon carbide device has failed is more accurate, thereby solving the problem that the bipolar degradation test of the silicon carbide device in the prior art only considers the DC current stress applied during the experiment, and it is difficult to assess the reliability of the bipolar degradation under high-frequency pulse current conditions in actual applications.

Description

Technical Field

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

[0002] Silicon carbide (SiC) materials have been widely studied and applied in the fields of high temperature, high frequency and high power due to their excellent properties such as wide bandgap, high critical breakdown electric field strength, high electron saturation drift velocity and high thermal conductivity. However, there are basal plane dislocations (BPDs) in SiC substrates and epitaxial materials. During the operation of SiC bipolar devices, the energy released by the recombination of electrons and holes causes stacking faults to propagate at the BPD. The stacking fault propagation area will reduce the carrier lifetime and cannot conduct current. This phenomenon is called bipolar degradation. For example, bipolar degradation of SiC diodes under forward working conditions will increase their on-state voltage drop, increase power loss, and affect the electrothermal characteristics and reliability of the device. For example, when the body diode of a silicon carbide metal oxide semiconductor field effect transistor (SiC MOSFET) is in freewheeling working conditions, the bipolar degradation of the body diode will increase the forward voltage drop of the body diode, affecting its application in the freewheeling circuit. It will also cause the forward forward voltage drop and on-resistance of the SiC MOSFET device to increase, seriously affecting the forward characteristics and reliability of the device.

[0003] Due to the limitations of the silicon carbide epitaxial wafer manufacturing process, the generation of base crystal plane dislocations cannot be completely avoided. There are great differences in the occurrence of base crystal plane dislocations in silicon carbide epitaxial wafers from different manufacturers, and the density of base crystal plane dislocation defects in different batches of products from the same manufacturer is also slightly different. Therefore, manufacturers and users need to evaluate the bipolar degradation of silicon carbide devices.

[0004] At present, the bipolar degradation test of SiC devices only considers the DC current stress applied during the experiment, which makes it difficult to assess the bipolar degradation reliability under high-frequency pulse current conditions in actual applications. Summary of the invention

[0005] The main purpose of the present application is to provide a bipolar degradation test method, silicon carbide device and system for a silicon carbide device, so as to at least solve the problem that the bipolar degradation test of the silicon carbide device in the prior art only considers the DC current stress applied during the experiment, and it is difficult to assess the reliability of bipolar degradation under high-frequency pulse current conditions in actual applications.

[0006] In order to achieve the above object, according to one aspect of the present application, a bipolar degradation test method for a silicon carbide device is provided, the method comprising:

[0007] Applying pulse currents of different magnitudes to a target silicon carbide device until the temperature of the target silicon carbide device reaches a target maximum withstand junction temperature, and determining that the corresponding pulse current applied is a maximum pulse current, wherein an initial pulse current applied to the target silicon carbide device for the first time is a preset pulse current corresponding to the specification of the target silicon carbide device;

[0008] Acquire a second current flow time, where the second current flow time is the current flow time of the target silicon carbide device when the maximum pulse current is applied;

[0009] After performing a bipolar degradation test on the target silicon carbide device using the second flow time and the maximum pulse current, the target silicon carbide device is left to stand, and after the target silicon carbide device is left to stand for a preset period of time, the current static characteristic index of the target silicon carbide device is obtained to obtain a first static characteristic index, and whether the target silicon carbide device has failed is determined based on the size of the first static characteristic index, wherein the first static characteristic index includes threshold voltage, on-resistance, on-voltage drop, drain-source leakage current, gate-source leakage current, body diode voltage drop, maximum withstand voltage, and thermal resistance.

[0010] Optionally, determining the second current flow time according to the initial pulse current, the target pulse current and the first current flow time includes:

[0011] Determining a bipolar degradation pulse current acceleration factor according to the initial pulse current and the target pulse current, wherein the bipolar degradation pulse current acceleration factor is an intermediate constant;

[0012] The second on-time is determined according to the bipolar degradation pulse current acceleration factor and the first on-time, where the first on-time is the on-time of the target silicon carbide device when the initial pulse current is applied.

[0013] Optionally, determining a bipolar degradation pulse current acceleration factor according to the initial pulse current and the target pulse current includes:

[0014] According to I AF =exp[β×(I stress -I normal )], determine the bipolar degradation pulse current acceleration factor, where I AF is the bipolar degenerate pulse current acceleration factor, β is the acceleration rate constant of the pulse current, I stress is the target pulse current, I normal is the initial pulse current.

[0015] Optionally, before determining the bipolar degradation pulse current acceleration factor according to the initial pulse current and the target pulse current, the method further includes:

[0016] The acceleration rate constant of the pulse current is determined to be a preset acceleration rate constant corresponding to the specification of the target silicon carbide device.

[0017] Optionally, determining the second flow time according to the bipolar degradation pulse current acceleration factor and the first flow time includes:

[0018] According to t stress =t normal / I AF , determine the second flow time, where t stress is the second flow time, t normal is the first flow time, I AF is the bipolar degradation pulse current acceleration factor.

[0019] Optionally, determining whether the target silicon carbide device has failed according to the magnitude of the first static characteristic indicator includes:

[0020] When the absolute value of the change rate of any one of the on-resistance, on-voltage drop, body diode voltage drop, and maximum withstand voltage in the first static characteristic indicator is greater than or equal to a first preset percentage, and / or the absolute value of the change rate of any one of the threshold voltage, drain-source leakage current, gate-source leakage current, and thermal resistance in the first static characteristic indicator is greater than or equal to a second preset percentage, it is determined that the target silicon carbide device has failed, and the second preset percentage is greater than the first preset percentage;

[0021] When the absolute values ​​of the change rates of the on-resistance, the on-voltage drop, the body diode voltage drop and the maximum withstand voltage in the first static characteristic indicator are all less than the first preset percentage, and the absolute values ​​of the change rates of the threshold voltage, the drain-source leakage current, the gate-source leakage current and the thermal resistance in the first static characteristic indicator are all less than the second preset percentage, it is determined that the target silicon carbide device is valid.

[0022] Optionally, applying pulse currents of different magnitudes to a target silicon carbide device until a temperature of the target silicon carbide device reaches a target maximum withstand junction temperature to determine a maximum pulse current includes:

[0023] The pulse current is continuously increased in a RAMP manner, and pulse currents of different magnitudes are applied to the target silicon carbide device until the temperature of the target silicon carbide device reaches the target maximum tolerance junction temperature, so as to determine the maximum pulse current.

[0024] Optionally, applying pulse currents of different magnitudes to a target silicon carbide device until a temperature of the target silicon carbide device reaches a target maximum withstand junction temperature to determine a maximum pulse current includes:

[0025] The pulse current is continuously increased with a preset step size, and pulse currents of different magnitudes are applied to the target silicon carbide device until the temperature of the target silicon carbide device reaches the target maximum tolerance junction temperature, so as to determine the maximum pulse current.

[0026] Optionally, before applying pulse currents of different magnitudes to the target silicon carbide device until the temperature of the target silicon carbide device reaches a target maximum withstand junction temperature to determine the maximum pulse current, the method further includes:

[0027] Performing a static test on each silicon carbide device to obtain a second static characteristic index, wherein the second static characteristic index includes a threshold voltage, an on-resistance, an on-voltage drop, a drain-source leakage current, a gate-source leakage current, a body diode voltage drop, a maximum withstand voltage, and a thermal resistance;

[0028] When all parameters in the second static characteristic index of the silicon carbide device are within corresponding preset ranges, determining that the silicon carbide device is a target silicon carbide device;

[0029] When at least one parameter in the second static characteristic index of the silicon carbide device is not within a corresponding preset range, it is determined that the silicon carbide device is a non-target silicon carbide device.

[0030] Optionally, in the process of applying pulse currents of different magnitudes to the target silicon carbide device until the temperature of the target silicon carbide device reaches a target maximum withstand junction temperature to determine the maximum pulse current, the method further includes:

[0031] The pulse current is adjusted by adjusting the current pulse width and the current duty cycle.

[0032] Optionally, in the process of applying pulse currents of different magnitudes to the target silicon carbide device until the temperature of the target silicon carbide device reaches a target maximum withstand junction temperature to determine the maximum pulse current, the method further includes:

[0033] The temperature of the target silicon carbide device at the current moment is determined according to the temperature forward conduction voltage mapping relationship and the forward conduction voltage of the target silicon carbide device at the current moment, wherein the temperature forward conduction voltage mapping relationship is a mapping relationship between the temperature and the forward conduction voltage of the target silicon carbide device.

[0034] Optionally, in the process of applying pulse currents of different magnitudes to the target silicon carbide device until the temperature of the target silicon carbide device reaches a target maximum withstand junction temperature to determine the maximum pulse current, the method further includes:

[0035] In the case where the target silicon carbide device is a MOS tube, the temperature of the target silicon carbide device at the current moment is determined according to a temperature-body diode voltage drop mapping relationship and the body diode voltage drop of the target silicon carbide device at the current moment, wherein the temperature-body diode voltage drop mapping relationship is a mapping relationship between the temperature of the target silicon carbide device and the body diode voltage drop.

[0036] According to another aspect of the present application, a silicon carbide device is provided, and the silicon carbide device is tested by using any one of the bipolar degradation test methods for the silicon carbide device.

[0037] According to another aspect of the present application, a bipolar degradation test system for a silicon carbide device is provided, and the bipolar degradation test system for a silicon carbide device comprises:

[0038] A silicon carbide device, wherein the silicon carbide device is tested by using any of the bipolar degradation test methods for the silicon carbide device;

[0039] A power supply device, electrically connected to the silicon carbide device, and configured to output different pulse currents;

[0040] A detection device is electrically connected to the silicon carbide device, and the detection device is used for real-time testing and collecting current and voltage.

[0041] Optionally, the bipolar degradation test system for the silicon carbide device further includes:

[0042] The cooling device is used to absorb the heat generated by the silicon carbide device during the flow process by using molten salt heat storage technology to ensure that the junction temperature of the silicon carbide device is kept constant during the flow process. The heat stored in the cooling device is used to heat up the silicon carbide device.

[0043] By applying the technical solution of the present application, the initial pulse current applied to the target silicon carbide device for the first time is a preset pulse current corresponding to the specification of the target silicon carbide device, so that the initial pulse current applied to the target silicon carbide device for the first time is more in line with the actual working conditions, and pulse currents of different sizes are applied to the target silicon carbide device until the temperature of the target silicon carbide device reaches the target maximum tolerance junction temperature, and the corresponding applied pulse current is determined to be the maximum pulse current, so that the maximum pulse current can be determined more accurately; based on the initial pulse current, the target pulse current and the flow time of the target silicon carbide device when the initial pulse current is applied, the flow time of the target silicon carbide device when the maximum pulse current is applied is determined time, so as to facilitate the subsequent bipolar degradation of the target silicon carbide device based on the second flow time and the maximum pulse current; the target silicon carbide device is subjected to a bipolar degradation test using the second flow time and the maximum pulse current, and is allowed to stand after the test, and after standing, whether the target silicon carbide device has failed is determined according to the size of the first static characteristic index, thereby making a more accurate determination of whether the target silicon carbide device has failed than the existing scheme, taking into account the bipolar degradation reliability under high-frequency pulse current conditions in actual applications, thereby solving the problem that the bipolar degradation test of silicon carbide devices in the prior art only considers the DC current stress applied during the experiment, and it is difficult to assess the bipolar degradation reliability under high-frequency pulse current conditions in actual applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The drawings constituting part of the present application are used to provide a further understanding of the present application. The exemplary embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0045] Figure 1 A schematic flow chart of a bipolar degradation testing method for a silicon carbide device provided according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0046] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0047] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present application.

[0048] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present application described here. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0049] For the convenience of description, some nouns or terms involved in the embodiments of the present application are explained below:

[0050] The on-time refers to the time that the device passes current in the on state. The on-time depends on the device's conduction characteristics, voltage and current, and is usually measured in microseconds or nanoseconds. The shorter the on-time, the faster the device responds, making it suitable for high-frequency and high-speed circuit applications. The on-time is also related to the device's conduction loss and thermal stability, and has an important impact on the device's performance and reliability.

[0051] Thermal resistance refers to the ease with which heat is transferred between materials inside a device when the device is working. The smaller the thermal resistance, the easier it is to transfer heat between materials inside the device, and the heat generated when the device is working can be dissipated more effectively, thereby maintaining the stability and performance of the device. Silicon carbide devices usually have lower thermal resistance, which can dissipate heat more effectively, improving the working efficiency and reliability of the device.

[0052] The molten salt heat storage technology is to heat the molten salt energy storage system with high-temperature and high-pressure steam to store the heat of high-grade steam, or use valley electricity to heat the molten salt energy storage system to generate high-parameter steam when releasing heat, which can be used for power generation, industrial steam supply or civil heating.

[0053] As introduced in the background technology, due to the limitations of the silicon carbide epitaxial wafer manufacturing process, the generation of basal plane dislocations cannot be completely avoided. There are great differences in the occurrence of basal plane dislocations in silicon carbide epitaxial wafers from different manufacturers, and the density of basal plane dislocation defects in different batches of products from the same manufacturer is also slightly different. Therefore, manufacturers and users need to evaluate the bipolar degradation of silicon carbide devices. In order to solve the problem that the bipolar degradation test of silicon carbide devices in the prior art only considers the DC current stress applied during the experiment, and it is difficult to assess the reliability of bipolar degradation under high-frequency pulse current conditions in actual applications, the embodiments of the present application provide a bipolar degradation test method for silicon carbide devices, silicon carbide devices and systems.

[0054] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0055] Figure 1 FIG. 1 is a flow chart of a bipolar degradation test method for a silicon carbide device provided according to an embodiment of the present application. Figure 1 As shown, the method comprises the following steps:

[0056] Step S101, applying pulse currents of different magnitudes to a target silicon carbide device until the temperature of the target silicon carbide device reaches a target maximum withstand junction temperature, and determining that the corresponding pulse current applied is a maximum pulse current, wherein an initial pulse current applied to the target silicon carbide device for the first time is a preset pulse current corresponding to the specification of the target silicon carbide device;

[0057] Specifically, the initial pulse current applied to the target silicon carbide device for the first time is a preset pulse current corresponding to the specification of the target silicon carbide device, so that the initial pulse current applied to the target silicon carbide device for the first time is more in line with actual working conditions.

[0058] Step S102, obtaining a second flow time, where the second flow time is the flow time of the target silicon carbide device when the maximum pulse current is applied;

[0059] Determine the second flow time according to the initial pulse current, one of all the pulse currents applied except the initial pulse current, and the first flow time, wherein the first flow time is the flow time of the target silicon carbide device when the initial pulse current is applied, and the second flow time is the flow time of the target silicon carbide device when the maximum pulse current is applied;

[0060] Specifically, the flow time of the target silicon carbide device when the above-mentioned maximum pulse current is applied is determined based on the above-mentioned initial pulse current, one of all the applied pulse currents except the above-mentioned initial pulse current, and the flow time of the above-mentioned target silicon carbide device when the above-mentioned initial pulse current is applied, so as to facilitate the subsequent bipolar degradation test of the above-mentioned target silicon carbide device based on the second flow time and the maximum pulse current, and the target pulse current is any pulse current among all the applied pulse currents except the above-mentioned initial pulse current.

[0061] The step S102 of determining the second flow time according to the initial pulse current, one of all applied pulse currents except the initial pulse current, and the first flow time includes:

[0062] Determine a bipolar degradation pulse current acceleration factor according to the initial pulse current and one of all pulse currents applied except the initial pulse current, wherein the bipolar degradation pulse current acceleration factor is an intermediate constant;

[0063] The second flow time is determined according to the bipolar degradation pulse current acceleration factor and the first flow time.

[0064] In one embodiment of the present application, the bipolar degradation pulse current acceleration factor is determined according to the initial pulse current and one of all applied pulse currents except the initial pulse current, including:

[0065] According to I AF =exp[β×(I stress -I normal )], determine the above bipolar degradation pulse current acceleration factor, where I AF is the above bipolar degenerate pulse current acceleration factor, β is the acceleration rate constant of the pulse current, I stress is one of all the pulse currents applied except the initial pulse current, I normal is the initial pulse current mentioned above.

[0066] Specifically, one of all the applied pulse currents except the initial pulse current may be the maximum pulse current, or may be a pulse current that is closest to the maximum pulse current among all the applied pulse currents.

[0067] In one embodiment of the present application, before determining the bipolar degradation pulse current acceleration factor according to the initial pulse current and one of all applied pulse currents except the initial pulse current, the method further includes:

[0068] The acceleration rate constant of the pulse current is determined to be a preset acceleration rate constant corresponding to the specification of the target silicon carbide device.

[0069] Specifically, by setting the specifications of the target silicon carbide device and the preset acceleration rate constant mapping relationship table, the acceleration rate constant of the pulse current is made more consistent with the actual working condition.

[0070] In one embodiment of the present application, determining the second flow time according to the bipolar degradation pulse current acceleration factor and the first flow time includes:

[0071] According to t stress =t normal / I AF , determine the second flow time mentioned above, where t stress is the second flow time mentioned above, t normalis the first flow time mentioned above, I AF is the above bipolar degradation pulse current acceleration factor.

[0072] Specifically, the flow time of the target silicon carbide device obtained when the above-mentioned maximum pulse current is applied is more in line with actual working conditions.

[0073] Step S103, after performing a bipolar degradation test on the target silicon carbide device using the second flow time and the maximum pulse current, the target silicon carbide device is left to stand, and after the target silicon carbide device is left to stand for a preset time, the current static characteristic index of the target silicon carbide device is obtained to obtain the first static characteristic index, and whether the target silicon carbide device has failed is determined according to the size of the first static characteristic index, wherein the first static characteristic index includes threshold voltage, on-resistance, on-voltage drop, drain-source leakage current, gate-source leakage current, body diode voltage drop, maximum withstand voltage, and thermal resistance.

[0074] The preset duration range is within 48 hours.

[0075] In the above steps, the initial pulse current applied to the target silicon carbide device for the first time is a preset pulse current corresponding to the specification of the target silicon carbide device, so that the initial pulse current applied to the target silicon carbide device for the first time is more in line with the actual working conditions, and pulse currents of different sizes are applied to the target silicon carbide device until the temperature of the target silicon carbide device reaches the target maximum withstand junction temperature, and the corresponding pulse current applied is determined to be the maximum pulse current, so that the maximum pulse current can be determined more accurately; according to the initial pulse current, one of all the pulse currents applied except the initial pulse current, and the flow time of the target silicon carbide device when the initial pulse current is applied, the target silicon carbide device is determined to be subjected to the maximum pulse current when the maximum pulse current is applied. The flow time of the current when the impulse current is applied is determined, so that it is convenient to perform bipolar degradation on the target silicon carbide device based on the second flow time and the maximum pulse current in the subsequent process; the target silicon carbide device is subjected to a bipolar degradation test using the second flow time and the maximum pulse current, and the device is allowed to stand after the test, and whether the target silicon carbide device has failed is determined according to the size of the first static characteristic index after the device is allowed to stand. Compared with the existing scheme, the determination of whether the target silicon carbide device has failed is more accurate, and the reliability of bipolar degradation under high-frequency pulse current conditions in actual applications is taken into account, thereby solving the problem that the bipolar degradation test of silicon carbide devices in the prior art only considers the DC current stress applied during the experiment, and it is difficult to assess the reliability of bipolar degradation under high-frequency pulse current conditions in actual applications.

[0076] In one embodiment of the present application, determining whether the target silicon carbide device fails according to the magnitude of the first static characteristic indicator includes:

[0077] When the absolute value of the change rate of any one of the on-resistance, the on-voltage drop, the body diode voltage drop, and the maximum withstand voltage in the first static characteristic index is greater than or equal to a first preset percentage, and / or the absolute value of the change rate of any one of the threshold voltage, the drain-source leakage current, the gate-source leakage current, and the thermal resistance in the first static characteristic index is greater than or equal to a second preset percentage, it is determined that the target silicon carbide device has failed, and the second preset percentage is greater than the first preset percentage;

[0078] When the absolute values ​​of the change rates of the on-resistance, the on-voltage drop, the body diode voltage drop and the maximum withstand voltage in the first static characteristic indicator are all less than the first preset percentage, and the absolute values ​​of the change rates of the threshold voltage, the drain-source leakage current, the gate-source leakage current and the thermal resistance in the first static characteristic indicator are all less than the second preset percentage, it is determined that the target silicon carbide device is effective.

[0079] Specifically, compared with the initial test value, if the change rate of on-resistance, on-voltage drop, body diode voltage drop, and maximum withstand voltage exceeds 5%, or the change rate of threshold voltage, drain-source leakage, gate-source leakage, and thermal resistance exceeds 20%, the device is judged to have failed. The first preset percentage can be 5% and the second preset percentage can be 20%.

[0080] In one embodiment of the present application, pulse currents of different magnitudes are applied to a target silicon carbide device until the temperature of the target silicon carbide device reaches a target maximum withstand junction temperature to determine a maximum pulse current, including:

[0081] The pulse current is continuously increased in a RAMP manner, and pulse currents of different magnitudes are applied to the target silicon carbide device until the temperature of the target silicon carbide device reaches the target maximum tolerance junction temperature, so as to determine the maximum pulse current.

[0082] Specifically, the pulse current is continuously increased in a RAMP manner, thereby achieving application of pulse currents of different magnitudes to the target silicon carbide device.

[0083] In one embodiment of the present application, pulse currents of different magnitudes are applied to a target silicon carbide device until the temperature of the target silicon carbide device reaches a target maximum withstand junction temperature to determine a maximum pulse current, including:

[0084] The pulse current is continuously increased with a preset step size, and pulse currents of different sizes are applied to the target silicon carbide device until the temperature of the target silicon carbide device reaches the target maximum tolerance junction temperature, so as to determine the maximum pulse current.

[0085] Specifically, the preset compensation may be 1. Compared with the RAMP method, continuously increasing the pulse current by a preset step size may more accurately find the maximum pulse current.

[0086] In one embodiment of the present application, before applying pulse currents of different magnitudes to the target silicon carbide device until the temperature of the target silicon carbide device reaches the target maximum withstand junction temperature to determine the maximum pulse current, the method further includes:

[0087] Performing a static test on each silicon carbide device to obtain a second static characteristic index, wherein the second static characteristic index includes a threshold voltage, an on-resistance, an on-voltage drop, a drain-source leakage current, a gate-source leakage current, a body diode voltage drop, a maximum withstand voltage, and a thermal resistance;

[0088] When all parameters of the second static characteristic index of the silicon carbide device are within corresponding preset ranges, determining the silicon carbide device as a target silicon carbide device;

[0089] When at least one parameter of the second static characteristic index of the silicon carbide device is not within a corresponding preset range, it is determined that the silicon carbide device is a non-target silicon carbide device.

[0090] Specifically, by setting the corresponding preset range, silicon carbide devices suitable for testing are screened. Since the threshold voltage, on-resistance, on-voltage drop, drain-source leakage current, gate-source leakage current, body diode voltage drop, maximum withstand voltage, and thermal resistance are taken into consideration, the screening results are more in line with actual working conditions.

[0091] In one embodiment of the present application, in the process of applying pulse currents of different magnitudes to the target silicon carbide device until the temperature of the target silicon carbide device reaches the target maximum tolerance junction temperature to determine the maximum pulse current, the method further includes:

[0092] The pulse current is adjusted by adjusting the current pulse width and the current duty cycle.

[0093] The pulse current is adjusted by adjusting the current pulse width and the current duty cycle, thereby achieving the purpose of applying pulse currents of different sizes to the target silicon carbide device.

[0094] In one embodiment of the present application, in the process of applying pulse currents of different magnitudes to the target silicon carbide device until the temperature of the target silicon carbide device reaches the target maximum tolerance junction temperature to determine the maximum pulse current, the method further includes:

[0095] The temperature of the target silicon carbide device at the current moment is determined according to the temperature forward conduction voltage mapping relationship and the forward conduction voltage of the target silicon carbide device at the current moment. The temperature forward conduction voltage mapping relationship is a mapping relationship between the temperature and the forward conduction voltage of the target silicon carbide device.

[0096] The forward conduction voltage in the mapping relationship between the temperature of the target silicon carbide device and the forward conduction voltage is the forward conduction voltage when a current of 0 to 200 mA is applied to the target silicon carbide device. The temperature of the target silicon carbide device at the current moment is determined based on the forward conduction voltage of the target silicon carbide device at the current moment, and the maximum tolerable junction temperature can be determined.

[0097] In one embodiment of the present application, in the process of applying pulse currents of different magnitudes to the target silicon carbide device until the temperature of the target silicon carbide device reaches the target maximum tolerance junction temperature to determine the maximum pulse current, the method further includes:

[0098] In the case where the target silicon carbide device is a MOS tube, the temperature of the target silicon carbide device at the current moment is determined according to the temperature-body diode voltage drop mapping relationship and the body diode voltage drop of the target silicon carbide device at the current moment. The temperature-body diode voltage drop mapping relationship is a mapping relationship between the temperature of the target silicon carbide device and the body diode voltage drop.

[0099] When the target silicon carbide device is a MOS tube, the body diode voltage drop can be used as a criterion for determining the temperature of the target silicon carbide device at the current moment. The body diode voltage drop in the mapping relationship between the temperature of the target silicon carbide device and the body diode voltage drop is the body diode voltage drop when a current of 0 to 200 mA is applied to the target silicon carbide device.

[0100] According to another aspect of the present application, a silicon carbide device is provided, and any one of the above-mentioned bipolar degradation test methods for silicon carbide devices is used to test the silicon carbide device. The initial pulse current applied to the above-mentioned target silicon carbide device for the first time is a preset pulse current corresponding to the specification of the above-mentioned target silicon carbide device, so that the initial pulse current applied to the above-mentioned target silicon carbide device for the first time is more in line with the actual working conditions, and pulse currents of different sizes are applied to the target silicon carbide device until the temperature of the above-mentioned target silicon carbide device reaches the target maximum tolerance junction temperature, and the corresponding pulse current applied is determined to be the maximum pulse current, so that the maximum pulse current can be determined more accurately; according to the above-mentioned initial pulse current, one of all the pulse currents applied except the above-mentioned initial pulse current, and the flow time of the above-mentioned target silicon carbide device when the above-mentioned initial pulse current is applied, the target silicon carbide device is determined to be subjected to the above-mentioned maximum pulse current when the above-mentioned maximum pulse current is applied. The current flow time is set at 100 ms, so that it is convenient to perform bipolar degradation on the target silicon carbide device based on the second current flow time and the maximum pulse current; the target silicon carbide device is subjected to bipolar degradation test using the second current flow time and the maximum pulse current, and is allowed to stand after the test, and whether the target silicon carbide device has failed is determined according to the size of the first static characteristic index after standing still, so that the determination of whether the target silicon carbide device has failed is more accurate than that of the existing scheme, and the reliability of bipolar degradation under high-frequency pulse current conditions in actual applications is taken into account, thereby solving the problem that the bipolar degradation test of silicon carbide devices in the prior art only considers the DC current stress applied during the experiment, and it is difficult to assess the reliability of bipolar degradation under high-frequency pulse current conditions in actual applications.

[0101] According to another aspect of the present application, a bipolar degradation test system for a silicon carbide device is provided, and the bipolar degradation test system for a silicon carbide device comprises:

[0102] A silicon carbide device, wherein the silicon carbide device is tested by any of the above-mentioned bipolar degradation test methods for the silicon carbide device;

[0103] A power supply device, electrically connected to the silicon carbide device, and configured to output different pulse currents;

[0104] A detection device is electrically connected to the silicon carbide device, and the detection device is used for real-time testing and collecting current and voltage.

[0105] By using the preset pulse current corresponding to the specification of the target silicon carbide device as the initial pulse current applied to the target silicon carbide device for the first time, the initial pulse current applied to the target silicon carbide device for the first time is more in line with the actual working conditions, and applying pulse currents of different sizes to the target silicon carbide device until the temperature of the target silicon carbide device reaches the target maximum withstand junction temperature, and determining that the corresponding pulse current applied is the maximum pulse current, so as to more accurately determine the maximum pulse current; determining the target silicon carbide device when applying the maximum pulse current based on the initial pulse current, one of all the pulse currents applied except the initial pulse current, and the flow time of the target silicon carbide device when applying the initial pulse current The current flow time is set at 100 ms, so that it is convenient to perform bipolar degradation on the target silicon carbide device based on the second current flow time and the maximum pulse current; the target silicon carbide device is subjected to bipolar degradation test using the second current flow time and the maximum pulse current, and is allowed to stand after the test, and whether the target silicon carbide device has failed is determined according to the size of the first static characteristic index after standing still, so that the determination of whether the target silicon carbide device has failed is more accurate than that of the existing scheme, and the reliability of bipolar degradation under high-frequency pulse current conditions in actual applications is taken into account, thereby solving the problem that the bipolar degradation test of silicon carbide devices in the prior art only considers the DC current stress applied during the experiment, and it is difficult to assess the reliability of bipolar degradation under high-frequency pulse current conditions in actual applications.

[0106] In one embodiment of the present application, the bipolar degradation test system for the silicon carbide device further includes:

[0107] The cooling device is used to absorb the heat generated by the above-mentioned silicon carbide device during the flow process by adopting the hot molten salt heat storage technology to ensure that the junction temperature of the above-mentioned silicon carbide device is maintained at a constant level during the flow process. The heat stored in the above-mentioned cooling device is used to heat up the above-mentioned silicon carbide device.

[0108] Specifically, a cooling device is provided to absorb the heat generated by the silicon carbide device during the current flow process by using molten salt heat storage technology to ensure that the junction temperature of the silicon carbide device is kept constant during the current flow process, thereby ensuring that the junction temperature of the device is kept constant during the current flow process.

[0109] It should be noted that the above electrical connection can be a direct electrical connection or an indirect electrical connection. Direct electrical connection means that two devices are directly connected, and indirect electrical connection means that other devices such as capacitors and resistors are also connected between the connected A and B.

[0110] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0111] From the above description, it can be seen that the above embodiments of the present application achieve the following technical effects:

[0112] 1) The bipolar degradation test method for silicon carbide devices of the present application makes the initial pulse current applied to the target silicon carbide device for the first time a preset pulse current corresponding to the specification of the target silicon carbide device, so that the initial pulse current applied to the target silicon carbide device for the first time is more in line with the actual working conditions, and applies pulse currents of different sizes to the target silicon carbide device until the temperature of the target silicon carbide device reaches the target maximum tolerance junction temperature, and determines that the corresponding pulse current applied is the maximum pulse current, so that the maximum pulse current can be determined more accurately; the target silicon carbide device is determined based on the initial pulse current, one of all the pulse currents applied except the initial pulse current, and the flow time of the target silicon carbide device when the initial pulse current is applied. The current flow time when the above-mentioned maximum pulse current is applied is used to facilitate the subsequent bipolar degradation of the above-mentioned target silicon carbide device based on the second current flow time and the maximum pulse current; the above-mentioned target silicon carbide device is subjected to a bipolar degradation test using the above-mentioned second current flow time and the above-mentioned maximum pulse current, and is allowed to stand after the test, and after standing, it is determined whether the above-mentioned target silicon carbide device has failed according to the size of the above-mentioned first static characteristic index, thereby more accurately determining whether the target silicon carbide device has failed than the existing scheme, taking into account the bipolar degradation reliability under high-frequency pulse current conditions in actual applications, and thus solving the problem that the bipolar degradation test of silicon carbide devices in the prior art only considers the DC current stress applied during the experiment, and it is difficult to assess the bipolar degradation reliability under high-frequency pulse current conditions in actual applications.

[0113] 2) The bipolar degradation test system for silicon carbide devices of the present application makes the initial pulse current applied to the target silicon carbide device for the first time a preset pulse current corresponding to the specification of the target silicon carbide device, so that the initial pulse current applied to the target silicon carbide device for the first time is more in line with the actual working conditions, applies pulse currents of different sizes to the target silicon carbide device until the temperature of the target silicon carbide device reaches the target maximum tolerance junction temperature, and determines that the corresponding pulse current applied is the maximum pulse current, so that the maximum pulse current can be determined more accurately; determines the target silicon carbide device based on the initial pulse current, one of all the pulse currents applied except the initial pulse current, and the flow time of the target silicon carbide device when the initial pulse current is applied. The current flow time when the above-mentioned maximum pulse current is applied is used to facilitate the subsequent bipolar degradation of the above-mentioned target silicon carbide device based on the second current flow time and the maximum pulse current; the above-mentioned target silicon carbide device is subjected to a bipolar degradation test using the above-mentioned second current flow time and the above-mentioned maximum pulse current, and is allowed to stand after the test, and after standing, it is determined whether the above-mentioned target silicon carbide device has failed according to the size of the above-mentioned first static characteristic index, thereby more accurately determining whether the target silicon carbide device has failed than the existing scheme, taking into account the bipolar degradation reliability under high-frequency pulse current conditions in actual applications, and thus solving the problem that the bipolar degradation test of silicon carbide devices in the prior art only considers the DC current stress applied during the experiment, and it is difficult to assess the bipolar degradation reliability under high-frequency pulse current conditions in actual applications.

[0114] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A bipolar degradation test method for a silicon carbide device, characterized in that: include: Applying pulse currents of different magnitudes to a target silicon carbide device until the temperature of the target silicon carbide device reaches a target maximum withstand junction temperature, and determining that the corresponding pulse current applied is a maximum pulse current, wherein an initial pulse current applied to the target silicon carbide device for the first time is a preset pulse current corresponding to the specification of the target silicon carbide device; Acquire a second current flow time, where the second current flow time is the current flow time of the target silicon carbide device when the maximum pulse current is applied; After performing a bipolar degradation test on the target silicon carbide device using the second current-passing time and the maximum pulse current, the target silicon carbide device is left to stand, and after the target silicon carbide device is left to stand for a preset time, a current static characteristic index of the target silicon carbide device is obtained to obtain a first static characteristic index, and whether the target silicon carbide device has failed is determined based on the size of the first static characteristic index.

2. The method according to claim 1, characterized in that Get the second flow time, including: Determine a bipolar degradation pulse current acceleration factor according to the initial pulse current and the target pulse current, wherein the bipolar degradation pulse current acceleration factor is an intermediate constant, and the target pulse current is any pulse current among all pulse currents applied except the initial pulse current; The second on-time is determined according to the bipolar degradation pulse current acceleration factor and the first on-time, wherein the first on-time is the on-time of the target silicon carbide device when the initial pulse current is applied.

3. The method according to claim 2, characterized in that Determining a bipolar degradation pulse current acceleration factor according to the initial pulse current and the target pulse current includes: According to I AF =exp[β×(I stress -I normal )], determine the bipolar degradation pulse current acceleration factor, where I AF is the bipolar degenerate pulse current acceleration factor, β is the acceleration rate constant of the pulse current, I stress is the target pulse current, I normal is the initial pulse current, and the target pulse current is any pulse current among all the applied pulse currents except the initial pulse current.

4. The method according to claim 2, characterized in that: Determining the second flow time according to the bipolar degradation pulse current acceleration factor and the first flow time includes: According to t stress =t normal / I AF , determine the second flow time, where t stress is the second flow time, t normal is the first flow time, I AF is the bipolar degradation pulse current acceleration factor.

5. The method according to claim 1, characterized in that Determining whether the target silicon carbide device fails according to the magnitude of the first static characteristic indicator includes: When the absolute value of the change rate of any one of the on-resistance, on-voltage drop, body diode voltage drop, and maximum withstand voltage in the first static characteristic indicator is greater than or equal to a first preset percentage, and / or the absolute value of the change rate of any one of the threshold voltage, drain-source leakage current, gate-source leakage current, and thermal resistance in the first static characteristic indicator is greater than or equal to a second preset percentage, it is determined that the target silicon carbide device has failed, and the second preset percentage is greater than the first preset percentage; When the absolute values ​​of the change rates of the on-resistance, the on-voltage drop, the body diode voltage drop and the maximum withstand voltage in the first static characteristic indicator are all less than the first preset percentage, and the absolute values ​​of the change rates of the threshold voltage, the drain-source leakage current, the gate-source leakage current and the thermal resistance in the first static characteristic indicator are all less than the second preset percentage, it is determined that the target silicon carbide device is valid.

6. The method according to claim 1, characterized in that Applying pulse currents of different magnitudes to a target silicon carbide device until the temperature of the target silicon carbide device reaches a target maximum withstand junction temperature to determine a maximum pulse current, including: The pulse current is continuously increased with a preset step size, and pulse currents of different magnitudes are applied to the target silicon carbide device until the temperature of the target silicon carbide device reaches the target maximum tolerance junction temperature, so as to determine the maximum pulse current.

7. The method according to claim 1, characterized in that Before applying pulse currents of different magnitudes to the target silicon carbide device until the temperature of the target silicon carbide device reaches a target maximum withstand junction temperature to determine the maximum pulse current, the method further includes: Performing a static test on each silicon carbide device to obtain a second static characteristic index, wherein the second static characteristic index includes a threshold voltage, an on-resistance, an on-voltage drop, a drain-source leakage current, a gate-source leakage current, a body diode voltage drop, a maximum withstand voltage, and a thermal resistance; When all parameters in the second static characteristic index of the silicon carbide device are within corresponding preset ranges, determining that the silicon carbide device is a target silicon carbide device; When at least one parameter in the second static characteristic index of the silicon carbide device is not within a corresponding preset range, it is determined that the silicon carbide device is a non-target silicon carbide device.

8. The method according to claim 1, characterized in that In the process of applying pulse currents of different magnitudes to the target silicon carbide device until the temperature of the target silicon carbide device reaches the target maximum withstand junction temperature to determine the maximum pulse current, the method further includes: The pulse current is adjusted by adjusting the current pulse width and the current duty cycle.

9. The method according to claim 1, characterized in that: In the process of applying pulse currents of different magnitudes to the target silicon carbide device until the temperature of the target silicon carbide device reaches the target maximum withstand junction temperature to determine the maximum pulse current, the method further includes: The temperature of the target silicon carbide device at the current moment is determined according to the temperature forward conduction voltage mapping relationship and the forward conduction voltage of the target silicon carbide device at the current moment, wherein the temperature forward conduction voltage mapping relationship is a mapping relationship between the temperature and the forward conduction voltage of the target silicon carbide device.

10. The method according to claim 1, characterized in that In the process of applying pulse currents of different magnitudes to the target silicon carbide device until the temperature of the target silicon carbide device reaches the target maximum withstand junction temperature to determine the maximum pulse current, the method further includes: In the case where the target silicon carbide device is a MOS tube, the temperature of the target silicon carbide device at the current moment is determined according to a temperature-body diode voltage drop mapping relationship and the body diode voltage drop of the target silicon carbide device at the current moment, wherein the temperature-body diode voltage drop mapping relationship is a mapping relationship between the temperature of the target silicon carbide device and the body diode voltage drop.

11. A silicon carbide device, characterized in that: in, The silicon carbide device is tested by using the bipolar degradation test method for the silicon carbide device according to any one of claims 1 to 10.

12. A bipolar degradation test system for silicon carbide devices, characterized in that: include: A silicon carbide device, wherein the silicon carbide device is tested by using the bipolar degradation test method for the silicon carbide device according to any one of claims 1 to 10; A power supply device, electrically connected to the silicon carbide device, and configured to output different pulse currents; A detection device is electrically connected to the silicon carbide device, and the detection device is used for real-time testing and collecting current and voltage.

13. The bipolar degradation test system for silicon carbide devices according to claim 12, characterized in that: The bipolar degradation test system of the silicon carbide device also includes: The cooling device is used to absorb the heat generated by the silicon carbide device during the flow process by using molten salt heat storage technology to ensure that the junction temperature of the silicon carbide device is kept constant during the flow process. The heat stored in the cooling device is used to heat up the silicon carbide device.

Images