Method and system for determining high temperature withstand voltage limit value of silicon carbide device

Abstract

The present application provides a method and system for determining a high-temperature withstand voltage limit value of a silicon carbide device. The method adjusts the temperature of a high-temperature oven to a preset maximum operating junction temperature, and continuously applies a reverse bias to a test group based on continuously increasing the reverse bias output by a DC source module, thereby achieving the purpose of testing the high-temperature withstand voltage limit value. In addition, after each application of the reverse bias to the test group for a first preset time, it is determined whether the high-temperature withstand voltage limit value of the test group is the current reverse bias according to the magnitude of current electrical performance parameters of the test group, and the current electrical performance parameters of the test group include the current gate leakage current, the current threshold voltage, and the current drain leakage current of the silicon carbide device of the test group, thereby making the determination of the high-temperature withstand voltage limit value of the test group more in line with actual working conditions, thereby solving the problem of low efficiency of the existing solution in determining the high-temperature withstand voltage limit value of SiC MOSFET.

Description

Technical Field

[0001] The present application relates to the technical field of testing silicon carbide devices, and in particular to a method and system for determining a high-temperature withstand voltage limit value of a silicon carbide device. Background Art

[0002] Silicon carbide (SiC) MOSFET is a metal-oxide-semiconductor field-effect transistor made of SiC semiconductor material. Compared with traditional silicon (Si) MOSFET, SiC MOSFET has the advantages of voltage resistance, high temperature resistance, fast switching speed and low resistance, and can be widely used in railway traction converters, photovoltaic inverters, wind power generation devices, electric vehicle drive systems and aerospace power supplies.

[0003] Performance, cost and reliability are three important dimensions that determine the commercialization process of SiC MOSFET, among which reliability is closely related to the actual service life of the device. Faced with increasingly stringent reliability requirements, the reliability design of devices should change from "simply meeting contract requirements" to "increasing the device's stress tolerance margin as much as possible to ensure that there are no failures during use." For device users, understanding the range and limits of SiC MOSFET's stress tolerance and clarifying the margin between the device's actual capabilities and the capabilities marked in the product data sheet will help users select suppliers with strong product quality assurance capabilities and ensure the application reliability of the selected devices; for device manufacturers, in the engineering development stage, based on the early failure modes exposed during the investigation of SiC MOSFET's actual capabilities, they can locate the device's weak links, evaluate product risks, and then optimize the process flow and structural design to achieve a steady increase in device reliability.

[0004] In actual applications, SiC MOSFET will be subjected to severe electrical and thermal coupling stresses brought by variable and complex working conditions such as surge, radiation or electrostatic damage, which puts forward more stringent high-temperature withstand voltage reliability requirements for the device. At present, the evaluation of SiC MOSFET's high-temperature withstand voltage capability is mainly based on constant stress tests. At the maximum operating junction temperature, a constant reverse bias slightly lower than the device's rated voltage is applied for 1000 hours to verify the stability of the device's performance under long-term blocking conditions.

[0005] According to this traditional method, it takes several months to find out the actual high-temperature withstand voltage range and limit of SiC MOSFET, which is time-consuming and inefficient. The evaluation time can be shortened by increasing the reverse bias voltage, but there is still a lack of standardized reverse voltage stress selection standards for the evaluation of the high-temperature withstand voltage limit of SiC devices. Blindly using too high a reverse bias voltage may cause the device to burn out instantly, which not only fails to achieve the purpose of mastering the actual capabilities of SiC MOSFET, but also causes unnecessary waste of devices. Therefore, it is necessary to provide an efficient and reliable SiC MOSFET high-temperature withstand voltage capability limit evaluation method and system to determine the actual withstand stress range of SiC MOSFET in a short time and low loss manner.

[0006] That is, the existing solution is less efficient in determining the high temperature withstand voltage limit of SiC MOSFET. Summary of the invention

[0007] The main purpose of the present application is to provide a method and system for determining a high temperature withstand voltage limit value of a silicon carbide device, so as to at least solve the problem that the existing solution is inefficient in determining the high temperature withstand voltage limit value of SiC MOSFET.

[0008] In order to achieve the above-mentioned object, according to one aspect of the present application, a method for determining a high-temperature withstand voltage limit value of a silicon carbide device is provided. The system for determining a high-temperature withstand voltage limit value of a silicon carbide device comprises a silicon carbide device, a high-temperature oven and a DC source module. The high-temperature oven is used to place the silicon carbide device. The first end of the DC source module is used to be electrically connected to the drain of the silicon carbide device. The second end of the DC source module is grounded. The method comprises:

[0009] A plurality of silicon carbide devices are used as a test group, and the temperature of the high-temperature oven is adjusted to a preset maximum operating junction temperature, and a reverse bias is continuously applied to the test group based on continuously increasing the reverse bias voltage output by the DC source module, wherein the preset maximum operating junction temperature is a temperature determined according to the specifications of the silicon carbide device, and the source and gate of the silicon carbide device are short-circuited;

[0010] After each application of a reverse bias voltage to the test group for a first preset time, obtaining current electrical performance parameters of the test group, the current electrical performance parameters of the test group including a current gate leakage current, a current threshold voltage, and a current drain leakage current of the silicon carbide device of the test group;

[0011] According to the magnitude of the current electrical performance parameter of the test group, it is determined whether the high temperature withstand voltage limit value of the test group is the current reverse bias voltage.

[0012] Optionally, determining whether the high temperature withstand voltage limit value of the test group is the current reverse bias voltage according to the current electrical performance parameter of the test group includes:

[0013] The silicon carbide device is determined to be a valid device when the current gate leakage current of the silicon carbide device is less than the product of the corresponding initial value and a first preset percentage, and the current drain leakage current is less than the product of the corresponding initial value and the first preset percentage, and the current threshold voltage is within a first preset range, the first preset range represents a range from the product of the initial value corresponding to the threshold voltage and the second preset percentage to the product of the initial value corresponding to the threshold voltage and a sixth preset percentage, and the sixth preset percentage is greater than the second preset percentage;

[0014] When the current gate leakage current of the silicon carbide device is greater than or equal to the product of the corresponding initial value and the first preset percentage, and / or the current drain leakage current is greater than or equal to the product of the corresponding initial value and the first preset percentage, and / or the current threshold voltage is not within the first preset range, determine that the silicon carbide device is a failed device;

[0015] When the first failure component ratio is greater than or equal to a third preset percentage, determining the high temperature withstand voltage limit value of the test group to be the last reverse bias voltage, and the first failure component ratio is the ratio of the failure components in the test group;

[0016] When the proportion of the first failed components is less than the third preset percentage, the reverse bias is continuously applied to the test group based on continuously increasing the reverse bias output by the DC source module.

[0017] Optionally, determining the high temperature withstand voltage limit value of the test group as the reverse bias voltage of the last time includes:

[0018] According to V max =V DSini +(n-1)×∆V d , determine the high temperature withstand voltage limit value of the test group, where V max is the high temperature withstand voltage limit value of the test group, V DSini is the starting value of the reverse bias, ∆V d is a preset step size, n is the current time, the preset step size is the product of the rated operating voltage of the test group and the fifth preset percentage, and the starting value of the reverse bias voltage is the product of the rated operating voltage of the test group and the fourth preset percentage.

[0019] Optionally, the DC source module includes a DC source and a resistor, a first end of the resistor serves as a first end of the DC source module, a second end of the resistor is electrically connected to the first end of the DC source, and the second end of the DC source is grounded, the current electrical performance parameter of the test group also includes a current resistance value, and in the process of determining whether the high temperature withstand voltage limit value of the test group is the current reverse bias voltage according to the magnitude of the current electrical performance parameter of the test group, the method further includes:

[0020] In the case where the current gate leakage current of the silicon carbide device is less than the product of the corresponding initial value and a first preset percentage, and the current drain leakage current is less than the product of the corresponding initial value and the first preset percentage, and the current threshold voltage is within a first preset range, and the current resistance value is within a second preset range, the silicon carbide device is determined to be a valid device, the first preset range represents a range from the product of the initial value corresponding to the threshold voltage and the second preset percentage to the product of the initial value corresponding to the threshold voltage and a sixth preset percentage, the sixth preset percentage is greater than the second preset percentage, and the second preset range represents a range from the product of the initial value corresponding to the resistance value and the second preset percentage to the product of the initial value corresponding to the resistance value and the sixth preset percentage;

[0021] When the current gate leakage current of the silicon carbide device is greater than or equal to the product of the corresponding initial value and the first preset percentage, and / or the current drain leakage current is greater than or equal to the product of the corresponding initial value and the first preset percentage, and / or the current threshold voltage is not within the first preset range, and / or the current resistance value is not within the second preset range, the silicon carbide device is determined to be a failed device.

[0022] Optionally, in the process of continuously applying the reverse bias to the test group based on continuously increasing the reverse bias output by the DC source module, the method further includes:

[0023] When the reverse bias is applied to the test group for the first time, the initial value of the reverse bias is determined to be the product of the rated operating voltage of the test group and a fourth preset percentage.

[0024] Optionally, the reverse bias is continuously applied to the test group based on continuously increasing the reverse bias output by the DC source module, including:

[0025] Reverse bias is continuously applied to the test group based on continuously increasing the reverse bias output by the DC source module with a preset step size, wherein the preset step size is the product of the rated operating voltage of the test group and a fifth preset percentage, and the fifth preset percentage is less than the fourth preset percentage.

[0026] Optionally, after determining whether the high temperature withstand voltage limit value of the test group is the current reverse bias voltage, the method further includes:

[0027] Using a plurality of additional silicon carbide devices as a verification group, adjusting the temperature of the high-temperature oven to a preset maximum operating junction temperature, and continuously applying a reverse bias to the verification group based on continuously increasing the reverse bias output by the DC source module;

[0028] After each application of a reverse bias voltage to the verification group for the first preset time, obtaining again the current electrical performance parameters of the verification group, the current electrical performance parameters of the verification group including the current gate leakage current, the current threshold voltage and the current drain leakage current of the silicon carbide device of the verification group;

[0029] Whether the high temperature withstand voltage limit value of the test group is valid is determined based on the magnitude of the current electrical performance parameter of the verification group.

[0030] Optionally, determining whether the high temperature withstand voltage limit value of the test group is valid according to the magnitude of the current electrical performance parameter of the verification group includes:

[0031] The silicon carbide device is determined to be a valid device when the current gate leakage current of the silicon carbide device is less than the product of the corresponding initial value and a first preset percentage, and the current drain leakage current is less than the product of the corresponding initial value and the first preset percentage, and the current threshold voltage is within a first preset range, the first preset range represents a range from the product of the initial value corresponding to the threshold voltage and the second preset percentage to the product of the initial value corresponding to the threshold voltage and a sixth preset percentage, and the sixth preset percentage is greater than the second preset percentage;

[0032] When the current gate leakage current of the silicon carbide device is greater than or equal to the product of the corresponding initial value and the first preset percentage, and / or the current drain leakage current is greater than or equal to the product of the corresponding initial value and the first preset percentage, and / or the current threshold voltage is not within the first preset range, determine that the silicon carbide device is a failed device;

[0033] In the case where the second failure component ratio is greater than or equal to a third preset percentage, determining that the high temperature withstand voltage limit value of the test group is invalid, the second failure component ratio being the ratio of the failure components in the verification group;

[0034] When the proportion of the second failed devices is less than the third preset percentage, the high temperature withstand voltage limit value of the test group is determined to be valid, and the reverse bias is continuously applied to the verification group based on continuously increasing the reverse bias output by the DC source module.

[0035] Optionally, the DC source module includes a DC source and a resistor, the first end of the resistor serves as the first end of the DC source module, the second end of the resistor is electrically connected to the first end of the DC source, the second end of the DC source is grounded, the current electrical performance parameter also includes a current resistance value, and in the process of determining whether the high temperature withstand voltage limit value of the test group is valid according to the magnitude of the current electrical performance parameter of the verification group, the method further includes:

[0036] In the case where the current gate leakage current of the silicon carbide device is less than the product of the corresponding initial value and a first preset percentage, and the current drain leakage current is less than the product of the corresponding initial value and the first preset percentage, and the current threshold voltage is within a first preset range, and the current resistance value is within a second preset range, the silicon carbide device is determined to be a valid device, the first preset range represents a range from the product of the initial value corresponding to the threshold voltage and the second preset percentage to the product of the initial value corresponding to the threshold voltage and a sixth preset percentage, the sixth preset percentage is greater than the second preset percentage, and the second preset range represents a range from the product of the initial value corresponding to the resistance value and the second preset percentage to the product of the initial value corresponding to the resistance value and the sixth preset percentage;

[0037] When the current gate leakage current of the silicon carbide device is greater than or equal to the product of the corresponding initial value and the first preset percentage, and / or the current drain leakage current is greater than or equal to the product of the corresponding initial value and the first preset percentage, and / or the current threshold voltage is not within the first preset range, and / or the current resistance value is not within the second preset range, the silicon carbide device is determined to be a failed device.

[0038] Optionally, after determining that the high temperature withstand voltage limit value of the test group is invalid, the method further includes:

[0039] According to V rmax =V max +(n-1)×∆V d , determine the high temperature withstand voltage limit value of the verification group, where V rmax is the high temperature withstand voltage limit value of the verification group, V max is the high temperature withstand voltage limit value of the test group, ∆V dis a preset step length, n is the current time, the preset step length is the product of the rated operating voltage of the test group and the fifth preset percentage, and the starting value of the reverse bias voltage is the product of the rated operating voltage of the test group and the fourth preset percentage;

[0040] A final high temperature withstand voltage limit value is determined to be the high temperature withstand voltage limit value of the verification group.

[0041] Optionally, in the process of continuously applying the reverse bias voltage to the verification group based on continuously increasing the reverse bias voltage output by the DC source module, the method further includes:

[0042] In the case where the reverse bias is applied to the verification group for the first time, a starting value of the reverse bias is determined as a product of a rated operating voltage of the verification group and a fourth preset percentage.

[0043] Optionally, in the process of continuously applying the reverse bias voltage to the verification group based on continuously increasing the reverse bias voltage output by the DC source module, the method further includes:

[0044] Reverse bias is continuously applied to the verification group based on continuously increasing the reverse bias output by the DC source module with a preset step size, wherein the preset step size is the product of the rated operating voltage of the verification group and the fifth preset percentage, and the fifth preset percentage is less than the fourth preset percentage.

[0045] According to another aspect of the present application, a system for determining a high-temperature withstand voltage limit value of a silicon carbide device is provided, the system for determining a high-temperature withstand voltage limit value of a silicon carbide device comprising: a silicon carbide device, a high-temperature oven and a direct current source module, the high-temperature oven being used to place the silicon carbide device, the first end of the direct current source module being used to be electrically connected to the drain of the silicon carbide device, the source and gate of the silicon carbide device being short-circuited, wherein the silicon carbide device is tested by using any one of the methods for determining a high-temperature withstand voltage limit value of a silicon carbide device.

[0046] Optionally, the DC source module includes a DC source and a resistor, the first end of the resistor serves as the first end of the DC source module, the second end of the resistor is electrically connected to the first end of the DC source, and the second end of the DC source is grounded.

[0047] Optionally, the silicon carbide device is an insulated gate field effect transistor.

[0048] By applying the technical solution of the present application, the temperature of the high-temperature oven is adjusted to a preset maximum operating junction temperature, and the reverse bias is continuously applied to the test group based on the continuous increase in the reverse bias output by the DC source module, thereby achieving the purpose of testing the high-temperature withstand voltage limit value. In addition, after each application of the reverse bias to the test group for a first preset time, it is determined whether the high-temperature withstand voltage limit value of the test group is the current reverse bias according to the size of the current electrical performance parameters of the test group, and the current electrical performance parameters of the test group include the current gate leakage current, the current threshold voltage and the current drain leakage current of the silicon carbide device of the test group, thereby making the determination of the high-temperature withstand voltage limit value of the test group more in line with actual working conditions, thereby solving the problem of low efficiency of the existing solution in determining the high-temperature withstand voltage limit value of SiC MOSFET. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] 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:

[0050] Figure 1 A schematic diagram of a system for determining a high temperature withstand voltage limit value of a silicon carbide device provided in an embodiment of the present application is shown;

[0051] Figure 2 A schematic flow chart of a method for determining a high temperature withstand voltage limit value of a silicon carbide device provided in accordance with an embodiment of the present application is shown;

[0052] Figure 3 A schematic diagram of setting parameters for a SiC MOSFET high temperature withstand voltage limit evaluation test provided in accordance with an embodiment of the present application is shown;

[0053] Figure 4 A schematic diagram showing a curve of a change in on-resistance of a device in a preliminary test group with a step reverse bias voltage during a high-temperature withstand voltage limit evaluation process provided by an embodiment of the present application;

[0054] Figure 5 A schematic diagram showing a curve of a change in on-resistance of a post-evaluation verification group device versus aging time during an estimation result verification process provided in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0055] 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.

[0056] 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.

[0057] 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.

[0058] As introduced in the background technology, in practical applications, SiC MOSFET will be subjected to severe electrical and thermal coupling stresses brought by variable and complex working conditions such as surge, radiation or electrostatic damage, which puts forward more stringent high-temperature withstand voltage reliability requirements for the device. At present, the evaluation of SiC MOSFET's high-temperature withstand voltage capability is mainly based on constant stress test. At the maximum operating junction temperature, a constant reverse bias slightly lower than the rated voltage of the device is applied for 1000 hours to verify the stability of the device's performance under long-term blocking conditions. According to this traditional method, it takes several months to find out the actual high-temperature withstand voltage range and limit of SiC MOSFET, which is time-consuming and inefficient; the evaluation time can be shortened by increasing the reverse bias, but due to the lack of standardized reverse voltage stress selection standards for the evaluation of the high-temperature withstand voltage limit of SiC devices, blindly using too high a reverse bias may cause the device to burn out instantly, which not only fails to achieve the purpose of mastering the actual capabilities of SiC MOSFET, but also causes unnecessary waste of devices. Therefore, it is necessary to provide an efficient and reliable method and system for evaluating the high-temperature withstand voltage capability limit of SiC MOSFET, so as to determine the actual withstand stress range of SiC MOSFET in a short time and low loss manner. In order to solve the problem that the existing schemes are inefficient in determining the high-temperature withstand voltage limit value of SiC MOSFET, the embodiments of the present application provide a method and system for determining the high-temperature withstand voltage limit value of a silicon carbide device.

[0059] 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.

[0060] like Figure 1 As shown ( Figure 1 The resistor and the current source in the device form a DC source module), a system for determining the high temperature withstand voltage limit value of a silicon carbide device comprises a silicon carbide device, a high temperature oven and a DC source module, wherein the high temperature oven is used to place the silicon carbide device, a first end of the DC source module is used to be electrically connected to the drain of the silicon carbide device, and a second end of the DC source module is grounded, Figure 2 FIG. 1 is a flow chart of a method for determining a high temperature withstand voltage limit value of a silicon carbide device according to an embodiment of the present application. Figure 2 As shown, the method comprises the following steps:

[0061] Step S201, taking a plurality of silicon carbide devices as a test group, adjusting the temperature of the high temperature oven to a preset maximum operating junction temperature, and continuously applying a reverse bias to the test group based on continuously increasing the reverse bias voltage output by the DC source module, wherein the preset maximum operating junction temperature is a temperature determined according to the specifications of the silicon carbide device, and the source and gate of the silicon carbide device are short-circuited;

[0062] The preset maximum operating junction temperature is selected according to the product data sheet and can be determined based on the specifications of the silicon carbide device.

[0063] Step S202, after each time a reverse bias is applied to the test group for a first preset time, obtaining current electrical performance parameters of the test group, wherein the current electrical performance parameters of the test group include a current gate leakage current, a current threshold voltage, and a current drain leakage current of the silicon carbide device of the test group;

[0064] Step S203, determining whether the high temperature withstand voltage limit value of the test group is the current reverse bias voltage according to the current electrical performance parameter of the test group.

[0065] In the above steps, since the temperature of the above-mentioned high-temperature oven is adjusted to the preset maximum operating junction temperature, and the reverse bias is continuously applied to the above-mentioned test group based on the continuous increase of the reverse bias output by the above-mentioned DC source module, the purpose of testing the high-temperature withstand voltage limit value is achieved. In addition, after each application of the reverse bias to the above-mentioned test group for a first preset time, it is determined whether the high-temperature withstand voltage limit value of the above-mentioned test group is the current reverse bias according to the size of the above-mentioned current electrical performance parameters of the above-mentioned test group, and the above-mentioned current electrical performance parameters of the above-mentioned test group include the current gate leakage current, the current threshold voltage and the current drain leakage current of the above-mentioned silicon carbide device of the above-mentioned test group, so that the determination of the high-temperature withstand voltage limit value of the test group is more in line with actual working conditions, thereby solving the problem of low efficiency of the existing scheme in determining the high-temperature withstand voltage limit value of SiC MOSFET.

[0066] Step S203, determining whether the high temperature withstand voltage limit value of the test group is the current reverse bias voltage according to the current electrical performance parameter of the test group, includes:

[0067] In the case where the current gate leakage current of the silicon carbide device is less than the product of the corresponding initial value and the first preset percentage, and the current drain leakage current is less than the product of the corresponding initial value and the first preset percentage, and the current threshold voltage is within a first preset range, the silicon carbide device is determined to be a valid device, and the first preset range represents a range from the product of the initial value corresponding to the threshold voltage and the second preset percentage to the product of the initial value corresponding to the threshold voltage and the sixth preset percentage, and the sixth preset percentage is greater than the second preset percentage;

[0068] Specifically, when the current gate leakage current of the silicon carbide device is less than the product of the corresponding initial value and the first preset percentage, and the current drain leakage current is less than the product of the corresponding initial value and the first preset percentage (i.e., 500%), and the current threshold voltage is within the first preset range, it is determined that the silicon carbide device is a valid device and can accept a higher reverse bias for testing. The second preset percentage is 80% and the sixth preset percentage is 120%.

[0069] When the current gate leakage current of the silicon carbide device is greater than or equal to the product of the corresponding initial value and the first preset percentage, and / or the current drain leakage current is greater than or equal to the product of the corresponding initial value and the first preset percentage, and / or the current threshold voltage is not within the first preset range, the silicon carbide device is determined to be a failed device;

[0070] Specifically, when the current gate leakage current of the silicon carbide device is greater than or equal to the product of the corresponding initial value and the first preset percentage, and / or the current drain leakage current is greater than or equal to the product of the corresponding initial value and the first preset percentage, and / or the current threshold voltage is not within the first preset range, the silicon carbide device is identified as a failed device.

[0071] When the proportion of the first failed devices is greater than or equal to the third preset percentage, the high temperature withstand voltage limit value of the test group is determined to be the reverse bias voltage of the last time, and the proportion of the first failed devices is the proportion of the failed devices in the test group;

[0072] Specifically, according to V max =V DSini +(n-1)×∆V d , determine the high temperature withstand voltage limit value of the above test group, where V maxis the high temperature withstand voltage limit value of the above test group, V DSini is the starting value of the reverse bias, ∆V d is the preset step size, n is the current time, the preset step size is the product of the rated operating voltage of the test group and the fifth preset percentage, and the starting value of the reverse bias voltage is the product of the rated operating voltage of the test group and the fourth preset percentage.

[0073] When the proportion of the first failed devices is less than the third preset percentage, the reverse bias is continuously applied to the test group based on continuously increasing the reverse bias output by the DC source module.

[0074] Specifically, when the proportion of the first failed devices is less than the third preset percentage (which may be 50%), it is considered that the device can withstand the current reverse bias.

[0075] In one embodiment of the present application, the DC source module includes a DC source and a resistor, the first end of the resistor serves as the first end of the DC source module, the second end of the resistor is electrically connected to the first end of the DC source, the second end of the DC source is grounded, the current electrical performance parameter of the test group also includes a current resistance value, and in the process of determining whether the high temperature withstand voltage limit value of the test group is the current reverse bias voltage according to the magnitude of the current electrical performance parameter of the test group, the method further includes:

[0076] In the case where the current gate leakage current of the silicon carbide device is less than the product of the corresponding initial value and the first preset percentage, and the current drain leakage current is less than the product of the corresponding initial value and the first preset percentage, and the current threshold voltage is within the first preset range, and the current resistance value is within the second preset range, the silicon carbide device is determined to be a valid device, the first preset range represents a range from the product of the initial value corresponding to the threshold voltage and the second preset percentage to the product of the initial value corresponding to the threshold voltage and the sixth preset percentage, the sixth preset percentage is greater than the second preset percentage, and the second preset range represents a range from the product of the initial value corresponding to the resistance value and the second preset percentage to the product of the initial value corresponding to the resistance value and the sixth preset percentage;

[0077] When the current gate leakage current of the silicon carbide device is greater than or equal to the product of the corresponding initial value and the first preset percentage, and / or the current drain leakage current is greater than or equal to the product of the corresponding initial value and the first preset percentage, and / or the current threshold voltage is not within the first preset range, and / or the current resistance value is not within the second preset range, the silicon carbide device is determined to be a failed device.

[0078] Specifically, compared with a solution that does not consider the resistance value, this embodiment takes the resistance value into consideration, so that the determination of effective devices and invalid devices can be more consistent with actual working conditions.

[0079] In one embodiment of the present application, in the process of continuously applying the reverse bias to the test group based on continuously increasing the reverse bias output by the DC source module, the method further includes:

[0080] When the reverse bias is applied to the test group for the first time, the initial value of the reverse bias is determined to be the product of the rated working voltage of the test group and a fourth preset percentage (80% to 100%).

[0081] Specifically, the starting voltage is set to 80%-90% of the rated operating voltage of the SiC device, that is, V DSini = (80%-90%) V DSmax ; Under the premise of ensuring that the SiC device to be tested will not be damaged suddenly, in order to improve the test efficiency, V DSini =100%V DSmax .

[0082] In one embodiment of the present application, the reverse bias voltage is continuously applied to the test group based on the continuous increase of the reverse bias voltage output by the DC source module, including:

[0083] The reverse bias is continuously applied to the test group based on the preset step size by continuously increasing the reverse bias output by the DC source module. The preset step size is the product of the rated operating voltage of the test group and the fifth preset percentage. The fifth preset percentage is less than the fourth preset percentage.

[0084] Specifically, ΔV d Set to 3%-5% of the rated voltage of the SiC device, that is, ∆V d = (3%-5%) V Dsmax .

[0085] In one embodiment of the present application, after determining whether the high temperature withstand voltage limit value of the test group is the reverse bias voltage of the current time, the method further includes:

[0086] Using a plurality of additional silicon carbide devices as a verification group, adjusting the temperature of the high-temperature oven to a preset maximum operating junction temperature, and continuously applying a reverse bias to the verification group based on continuously increasing the reverse bias output by the DC source module;

[0087] After each application of the reverse bias voltage to the verification group for the first preset time, obtaining the current electrical performance parameters of the verification group again, wherein the current electrical performance parameters of the verification group include the current gate leakage current, the current threshold voltage and the current drain leakage current of the silicon carbide device of the verification group;

[0088] According to the magnitude of the above-mentioned current electrical performance parameters of the above-mentioned verification group, it is determined whether the high-temperature withstand voltage limit value of the above-mentioned test group is valid.

[0089] Specifically, since a verification group is required for verification, the first preset time is 16-24 hours.

[0090] In one embodiment of the present application, determining whether the high temperature withstand voltage limit value of the test group is valid according to the magnitude of the current electrical performance parameter of the verification group includes:

[0091] In the case where the current gate leakage current of the silicon carbide device is less than the product of the corresponding initial value and the first preset percentage, and the current drain leakage current is less than the product of the corresponding initial value and the first preset percentage, and the current threshold voltage is within a first preset range, the silicon carbide device is determined to be a valid device, and the first preset range represents a range from the product of the initial value corresponding to the threshold voltage and the second preset percentage to the product of the initial value corresponding to the threshold voltage and the sixth preset percentage, and the sixth preset percentage is greater than the second preset percentage;

[0092] When the current gate leakage current of the silicon carbide device is greater than or equal to the product of the corresponding initial value and the first preset percentage, and / or the current drain leakage current is greater than or equal to the product of the corresponding initial value and the first preset percentage, and / or the current threshold voltage is not within the first preset range, the silicon carbide device is determined to be a failed device;

[0093] In the case where the second failure component ratio is greater than or equal to the third preset percentage, it is determined that the high temperature withstand voltage limit value of the test group is invalid, and the second failure component ratio is the ratio of the failure components in the verification group;

[0094] When the proportion of the second failed devices is less than the third preset percentage, the high temperature withstand voltage limit value of the test group is determined to be valid, and the reverse bias is continuously applied to the verification group based on continuously increasing the reverse bias output by the DC source module.

[0095] Specifically, it is the same as the test group and will not be elaborated here.

[0096] In one embodiment of the present application, the DC source module includes a DC source and a resistor, the first end of the resistor serves as the first end of the DC source module, the second end of the resistor is electrically connected to the first end of the DC source, the second end of the DC source is grounded, the current electrical performance parameter also includes a current resistance value, and in the process of determining whether the high temperature withstand voltage limit value of the test group is valid according to the magnitude of the current electrical performance parameter of the verification group, the method further includes:

[0097] In the case where the current gate leakage current of the silicon carbide device is less than the product of the corresponding initial value and the first preset percentage, and the current drain leakage current is less than the product of the corresponding initial value and the first preset percentage, and the current threshold voltage is within the first preset range, and the current resistance value is within the second preset range, the silicon carbide device is determined to be a valid device, the first preset range represents a range from the product of the initial value corresponding to the threshold voltage and the second preset percentage to the product of the initial value corresponding to the threshold voltage and the sixth preset percentage, the sixth preset percentage is greater than the second preset percentage, and the second preset range represents a range from the product of the initial value corresponding to the resistance value and the second preset percentage to the product of the initial value corresponding to the resistance value and the sixth preset percentage;

[0098] When the current gate leakage current of the silicon carbide device is greater than or equal to the product of the corresponding initial value and the first preset percentage, and / or the current drain leakage current is greater than or equal to the product of the corresponding initial value and the first preset percentage, and / or the current threshold voltage is not within the first preset range, and / or the current resistance value is not within the second preset range, the silicon carbide device is determined to be a failed device.

[0099] Specifically, similar to the test group, since the resistance value is taken into consideration, the determination of valid devices and failed devices is more accurate.

[0100] In one embodiment of the present application, after determining that the high temperature withstand voltage limit value of the test group is invalid, the method further includes:

[0101] According to V rmax =V max +(n-1)×∆V d , determine the high temperature withstand voltage limit value of the above verification group, where V rmax is the high temperature withstand voltage limit value of the above verification group, V max is the high temperature withstand voltage limit value of the above test group, ∆V dis a preset step length, n is the current time, the preset step length is the product of the rated operating voltage of the test group and the fifth preset percentage, and the starting value of the reverse bias voltage is the product of the rated operating voltage of the test group and the fourth preset percentage;

[0102] Determine the final high temperature withstand voltage limit value to be the above-mentioned high temperature withstand voltage limit value of the above-mentioned verification group.

[0103] Specifically, it is the same as the verification group and will not be elaborated here.

[0104] In one embodiment of the present application, in the process of continuously applying a reverse bias to the verification group based on continuously increasing the reverse bias output by the DC source module, the method further includes:

[0105] In the case where the reverse bias is applied to the verification group for the first time, the starting value of the reverse bias is determined to be the product of the rated operating voltage of the verification group and a fourth preset percentage.

[0106] Specifically, the starting voltage is set to 80%-90% of the rated operating voltage of the SiC device, that is, V DSini = (80%-90%) V DSmax ; Under the premise of ensuring that the SiC device to be tested will not be damaged suddenly, in order to improve the test efficiency, V DSini =100%V DSmax .

[0107] In one embodiment of the present application, in the process of continuously applying a reverse bias to the verification group based on continuously increasing the reverse bias output by the DC source module, the method further includes:

[0108] Based on the preset step size, the reverse bias voltage output by the DC source module is continuously increased, and the reverse bias voltage is continuously applied to the verification group. The preset step size is the product of the rated operating voltage of the verification+ group and the fifth preset percentage (i.e., 3-5%), and the fifth preset percentage is less than the fourth preset percentage (80%-100%).

[0109] Specifically, ΔV d Set to 3%-5% of the rated voltage of the SiC device, that is, ∆V d = (3%-5%) V Dsmax .

[0110] In addition, a specific method for determining the high temperature withstand voltage limit value of a silicon carbide device is provided, comprising the following steps:

[0111] Step S1, selecting a SiC MOSFET to be tested;

[0112] Step S2, initially measuring and recording various electrical performance parameters of the selected device, and each index parameter should be qualified in the initial measurement;

[0113] Step S3, dividing the devices that have passed the initial electrical performance test in step S2 into a preliminary test group and a post-evaluation verification group; the preliminary verification group is used to carry out high-temperature withstand voltage limit evaluation test to estimate the actual high-temperature withstand voltage capability of SiC MOSFET; the post-evaluation verification group is used to verify the accuracy of the estimated results;

[0114] Step S4, maintaining the ambient temperature at the highest operating junction temperature of the SiC MOSFET to be tested, gradually increasing the reverse bias voltage applied to the devices in the previous test group, i.e., the drain-source voltage VDS, repeatedly measuring the various electrical performance parameters of the devices (i.e.), and conducting a high temperature withstand voltage limit evaluation test;

[0115] Step S5, using the estimated value of the high temperature withstand voltage limit obtained in step S4 as the reverse bias applied to the devices in the post-evaluation verification group, conducting a long-term aging test at the highest operating junction temperature of the devices, and verifying the estimated result;

[0116] Step S6, after the aging test is completed, the electrical performance parameters of the devices in the verification group evaluated in step S5 are re-tested. If the parameters are still within the specification requirements, it can be determined that the high-temperature withstand voltage limit estimate obtained in step S4 is the high-temperature withstand voltage capability limit of the SiC MOSFET to be tested; if the parameters are not within the specification requirements, the estimate will be reduced and the verification test will be carried out again until the parameters of the verification group devices are re-tested and maintained within the specification requirements, and the high-temperature withstand voltage capability limit of the SiC MOSFET to be tested can be determined.

[0117] The electrical performance parameters of SiC MOSFET that need to be tested include: threshold voltage V GS（th） , gate leakage current I GSS , resistor R DS（on） , drain leakage current I DSS .

[0118] When conducting a high-temperature withstand voltage limit evaluation test or an estimated result verification test, the gate and source of the SiC MOSFET must be short-circuited to maintain the gate-source voltage V GS =0V to ensure that the device works in the blocking state.

[0119] In the above step S4, the SiC MOSFET high temperature withstand voltage limit evaluation test parameters need to be set in advance, including:

[0120] The maximum operating junction temperature of the device under test is T jmax :Select according to the product data sheet;

[0121] Reverse bias (drain-source voltage VDS) application starting point V DSini:The voltage starting point shall not be higher than the rated working voltage V of the device DSmax Considering the derating principle, the starting voltage is set to 80%-90% of the rated operating voltage of the SiC device, that is, V DSini = (80%-90%) V DSmax ; Under the premise of ensuring that the SiC device to be tested will not be damaged suddenly, in order to improve the test efficiency, V DSini =100%V DSmax ;

[0122] The step increment of reverse bias voltage (drain-source voltage VDS) ∆Vd is: Since SiC MOSFET may experience voltage overshoot higher than the rated value during high-frequency switching, V DS Upward step mode, that is, ∆V d If the step increment is too large, the device will burn out instantly, which will not only fail to achieve the purpose of mastering the actual capabilities of SiC MOSFET, but also cause unnecessary waste of devices. d The value should be consistent with the SiC MOSFET rated operating voltage V DSmax For devices with lower voltage levels, a smaller ∆V d ; For devices with higher voltage levels, ∆V should be appropriately increased d To improve the test efficiency. As shown in Table 1, ∆V d Set to 3%-5% of the rated voltage of the SiC device, that is, ∆V d = (3%-5%) V DSmax .

[0123] Table 1

[0124]

[0125] Each level of reverse bias holding time ∆t: Set the holding time ∆t between 16h-24h.

[0126] Step S4 specifically includes the following process:

[0127] Step S4-1, placing the SiC devices of the preliminary test group into the test equipment;

[0128] Step S4-2, adjust the temperature inside the device cavity to T jmax , the reverse bias voltage applied to the device is set to V DSini , maintain the gate-source voltage V GS =0V, the electrothermal stress is applied for ∆t;

[0129] Step S4-3, after ∆t time, take out the device and retest various electrical performance parameters;

[0130] Step S4-4, analyzing the test data, determining whether the SiC device has failed, counting the number of failed devices, and performing failure analysis on these devices to locate weak links;

[0131] Step S4-5: If the number of failed devices is ≥ 50% of the total number of devices in the previous test group, the test is stopped. Otherwise, the reverse voltage of the device is increased by ∆V d , and other conditions remain unchanged, the duration is ∆t, and so on, the cycle is repeated n times until the number of failed devices exceeds 50%, V DSini +(n-1)×∆V d This is the estimated value of the high-temperature withstand voltage limit of SiC MOSFET.

[0132] Furthermore, the SiC MOSFET device failure criterion in step S4-4 is: the device re-measures the leakage current I DSS or I GSS If the value reaches 5 times or more of the initial measurement value, or the deviation of other performance parameters from the initial measurement value exceeds 20%, the device is considered to have failed.

[0133] Furthermore, in step S5, the long-term aging test used to verify the estimated results should have an aging duration of no less than 100 hours.

[0134] Further, in step S6, the specification requirements of the index parameters refer to: the device re-measures the leakage current I DSS or I GSS If the deviation of other performance parameters from the initial measured values ​​does not exceed 20% and is not more than 5 times of the initial measured values, then the parameters of each index are still within the specification requirements.

[0135] Further, in step S6, if the parameters of the verification group device retest are still within the specification requirements, then the estimated value V in step S4 is DSini +(n-1)×∆V d This is the high temperature withstand voltage limit of the SiC MOSFET to be tested. If the parameters of the verification group device retest are not within the specification requirements, the estimated value will be reduced by ∆V d , re-conduct the post-evaluation test, and so on, for x times, until the parameters of the verification group devices are retested and maintained within the specification requirements, V DSini +(n-1-x)×∆V d This is the high temperature withstand voltage limit of the SiC MOSFET to be tested.

[0136] By using the reverse bias step method to evaluate the high-temperature withstand voltage limit of SiC MOSFET at the highest operating junction temperature, the high-temperature withstand voltage limit capability of the device can be obtained in a shorter time, while effectively avoiding the waste of devices caused by blindly applying high voltage. For device designers, the provided step-by-step evaluation process can expose the early failure mode of SiC MOSFET in order to optimize device design. It provides device users with an effective method to detect the high-temperature withstand voltage range and limit of SiC MOSFET, so as to grasp the reliability margin of the device and ensure the high reliability of the selected device.

[0137] The high temperature oven is used to provide the constant temperature environment required for the test, eliminate the influence of external humidity on the test results, and also play the role of electromagnetic shielding; SiC MOSFET is the device to be tested; the DC source provides a reverse voltage V between the drain D and the source S of the SiC MOSFET to be tested DS ; To avoid damage to the test equipment caused by unpredictable discharge, a protective resistor is introduced into the circuit; During the test, the gate G and source S of the SiC MOSFET are kept short-circuited, that is, V GS =0V to ensure that the device under test works in the blocking state.

[0138] The specific implementation process of this application is as follows:

[0139] Select the SiC MOSFET to be tested, and initially measure and record the electrical performance parameters of the selected device.

[0140] SiC MOSFET is selected as the insulated gate field effect transistor, a total of 5 pieces, the manufacturer is Infineon, the model is IMW120R220M1H, the package form is TO-247-3, the rated working voltage is V DSmax is 1200V, the maximum operating junction temperature T jmax The temperature is 175℃. The selected devices are numbered #1~#5, and the electrical performance parameters of the selected devices are initially tested using the power device analyzer Keysight B1505A;

[0141] The test sequence and conditions of each parameter are listed in Table 2.

[0142] Table 2

[0143]

[0144] The initial test results of the devices are shown in Table 3. All parameters of the five devices are qualified in the initial test. The SiC MOSFET devices that have passed the initial test are grouped, where #1, #2 and #3 devices are set as the preliminary test group, and #4 and #5 devices are set as the post-evaluation verification group.

[0145] Table 3

[0146]

[0147] based on Figure 1 The test circuit diagram shown in the figure is used to carry out high temperature withstand voltage limit evaluation test on three SiC MOSFET devices in the previous test group. The test parameters are set as follows: Figure 3 As shown in the figure, the temperature in the oven is kept at the maximum operating junction temperature T specified in the SiC MOSFET product data sheet. jmax =175℃ unchanged; reverse bias (drain-source voltage V DS ) Apply the starting point V Dsini Set to 80% of the rated operating voltage of the SiC MOSFET under test, that is, V DSini =0.8×1200V=960V; the step increment of reverse bias voltage (drain-source voltage VDS) is ∆V d Set to 4% of the rated voltage, ∆V d =0.04×1200V≈50V; the reverse bias holding time ∆t of each level is set to 16h.

[0148] The high temperature withstand voltage limit evaluation test of the three devices in the preliminary test group was performed as follows: Under the condition of maintaining the ambient temperature at 175°C, the reverse bias voltage applied to the test group devices was gradually increased with a starting voltage of 960V and a step increment of 50V. After each voltage level was maintained for 16 hours, the performance parameters of the devices were re-tested and compared with the initial measured values. DSS or I GSS If the value reaches 5 times or more of the initial test value, or the other performance parameters deviate by more than 20% compared with the initial test value, the device is considered to be failed and removed, and the remaining devices continue to be tested. The test is stopped until the number of failed devices accumulates to 2. The reverse bias applied when the test is stopped minus 1 step increment, and the resulting voltage value is the estimated value of the high temperature withstand voltage limit of SiC MOSFET.

[0149] During the test, the threshold voltage, drain-source leakage, and gate leakage of devices #1-#3 did not change significantly with the step reverse voltage, and the on-resistance degraded significantly. The on-resistance change curve of the device in the early test group with the step reverse bias voltage is shown in Figure 2. Figure 4 As shown in the figure, when the reverse bias voltage is stepped from 960V to 1360V, there is no obvious performance degradation in the three devices, and the variation range of the re-measured values ​​is within 2%; when the reverse bias voltage is increased to 1410V, the performance of the #2 and #3 devices is still stable, while the on-resistance RDS(on) of the #1 device increases to 294.071mΩ, which is +28.5% offset compared with the initial measured value of 228.8mΩ, so the #1 device is judged to be failed; when the reverse bias voltage is stepped to 1460V and maintained for 16h, the performance of the #3 device is still stable, while the on-resistance RDS(on) of the #2 device is increased .... DS（on）It increases to 1340mΩ, which is +472.6% offset from the initial value of 234.03mΩ, far exceeding the 20% set in the failure criterion, so the #2 device is judged to be failed. In summary, when the reverse bias step number n=10, the cumulative number of failed devices in the early test group reached 2, exceeding 50% of the total. The estimated high temperature withstand voltage limit of SiC MOSFET is 960V+(10-1)×50V=1410V.

[0150] based on Figure 1 The test circuit diagram shown in the figure uses an estimated value of 1410V as the reverse bias voltage (i.e., drain-source voltage V DS =1410V), and carried out long-term aging tests under the condition of maintaining the temperature at 175℃ to verify the estimated results. As the aging time increases, the threshold voltage, drain-source leakage, gate leakage and on-resistance offset of devices #4 and #5 are all within 2%. Among them, the on-resistance change curve of the post-evaluation verification group device with aging time is shown in the figure below. Figure 5 As shown. As can be seen from the figure, after 360h of high temperature and high pressure aging test, the performance of #4 and #5 devices is still stable. Compared with the initial measured value, the on-resistance of the #4 device increases first and then decreases with the aging time, with the highest value being 236.142mΩ and the offset being 1.46%; during the aging process, the highest on-resistance of the #5 device is 228.782mΩ, with an offset of 1.58% compared with the initial measured value. In summary, in the estimated result verification test, the index parameters of the two devices in the post-evaluation verification group are still within the specification requirements, and it is determined that 1410V is the high temperature (175℃) withstand voltage limit of the SiC MOSFET to be tested.

[0151] In the above embodiment, the high temperature withstand voltage limit capability of the test group SiC MOSFET is estimated by stepping the reverse bias voltage at a temperature of 175°C, and then the estimated value 1410V is used as the reverse bias voltage (i.e., the drain-source voltage V DS ), a long-term aging test was carried out at a temperature of 175°C to verify the estimated results and obtain the high-temperature withstand voltage limit of the SiC MOSFET to be tested. The entire process took a total of about 520 hours, which was shorter and more efficient than the time (several months) required to find the limit using the traditional constant stress method.

[0152] The present application can be applied to the evaluation of high temperature withstand voltage limit capability of SiC MOSFET devices with different voltage levels / current capabilities, but is not limited to that shown in this embodiment.

[0153] like Figure 1As shown, the present application provides a system for determining the high-temperature withstand voltage limit value of a silicon carbide device, and the system for determining the high-temperature withstand voltage limit value of a silicon carbide device includes: a silicon carbide device, a high-temperature oven and a DC source module, wherein the high-temperature oven is used to place the silicon carbide device, the first end of the DC source module is used to be electrically connected to the drain of the silicon carbide device, and the source and gate of the silicon carbide device are short-circuited, wherein any one of the above-mentioned methods for determining the high-temperature withstand voltage limit value of the silicon carbide device is used to test the silicon carbide device.

[0154] In the above system, since the temperature of the above-mentioned high-temperature oven is adjusted to a preset maximum operating junction temperature, and the reverse bias is continuously applied to the above-mentioned test group based on the continuous increase of the reverse bias output by the above-mentioned DC source module, the purpose of testing the high-temperature withstand voltage limit value is achieved. In addition, after each application of the reverse bias to the above-mentioned test group for a first preset time, it is determined whether the high-temperature withstand voltage limit value of the above-mentioned test group is the above-mentioned reverse bias voltage of the current time according to the size of the above-mentioned current electrical performance parameters of the above-mentioned test group, and the above-mentioned current electrical performance parameters of the above-mentioned test group include the current gate leakage current, the current threshold voltage and the current drain leakage current of the above-mentioned silicon carbide device of the above-mentioned test group, so that the determination of the high-temperature withstand voltage limit value of the test group is more in line with actual working conditions, thereby solving the problem of low efficiency of the existing scheme in determining the high-temperature withstand voltage limit value of SiC MOSFET.

[0155] like Figure 1 As shown, the DC source module includes a DC source and a resistor, the first end of the resistor serves as the first end of the DC source module, the second end of the resistor is electrically connected to the first end of the DC source, and the second end of the DC source is grounded.

[0156] Specifically, the DC source module is used to provide reverse bias, and the resistor is used to protect the system.

[0157] In one embodiment of the present application, the silicon carbide device is an insulated gate field effect transistor.

[0158] 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.

[0159] 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.

[0160] From the above description, it can be seen that the above embodiments of the present application achieve the following technical effects:

[0161] 1) The method for determining the high-temperature withstand voltage limit value of the silicon carbide device of the present application adjusts the temperature of the high-temperature oven to a preset maximum operating junction temperature, and continuously applies a reverse bias to the test group based on continuously increasing the reverse bias output by the DC source module, thereby achieving the purpose of testing the high-temperature withstand voltage limit value. In addition, after each application of the reverse bias to the test group for a first preset time, it is determined whether the high-temperature withstand voltage limit value of the test group is the current reverse bias value according to the magnitude of the current electrical performance parameters of the test group, and the current electrical performance parameters of the test group include the current gate leakage current, the current threshold voltage and the current drain leakage current of the silicon carbide device of the test group, thereby making the determination of the high-temperature withstand voltage limit value of the test group more in line with actual working conditions, thereby solving the problem of low efficiency of the existing scheme in determining the high-temperature withstand voltage limit value of SiC MOSFET.

[0162] 2) The system for determining the high-temperature withstand voltage limit value of the silicon carbide device of the present application adjusts the temperature of the above-mentioned high-temperature oven to a preset maximum operating junction temperature, and continuously applies reverse bias to the above-mentioned test group based on continuously increasing the reverse bias output by the above-mentioned DC source module, thereby achieving the purpose of testing the high-temperature withstand voltage limit value. In addition, after each application of reverse bias to the above-mentioned test group for a first preset time, it is determined whether the high-temperature withstand voltage limit value of the above-mentioned test group is the above-mentioned reverse bias of the current time according to the size of the above-mentioned current electrical performance parameters of the above-mentioned test group, and the above-mentioned current electrical performance parameters of the above-mentioned test group include the current gate leakage current, current threshold voltage and current drain leakage current of the above-mentioned silicon carbide device of the above-mentioned test group, so that the determination of the high-temperature withstand voltage limit value of the test group is more in line with actual working conditions, thereby solving the problem of low efficiency of the existing scheme in determining the high-temperature withstand voltage limit value of SiC MOSFET.

[0163] 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 method for determining a high temperature withstand voltage limit value of a silicon carbide device, wherein the system for determining a high temperature withstand voltage limit value of a silicon carbide device comprises a silicon carbide device, a high temperature oven and a direct current source module, wherein the high temperature oven is used to place the silicon carbide device, the first end of the direct current source module is used to be electrically connected to the drain of the silicon carbide device, and the second end of the direct current source module is grounded, wherein: include: A plurality of silicon carbide devices are used as a test group, and the temperature of the high-temperature oven is adjusted to a preset maximum operating junction temperature, and a reverse bias is continuously applied to the test group based on continuously increasing the reverse bias voltage output by the DC source module, wherein the preset maximum operating junction temperature is a temperature determined according to the specifications of the silicon carbide device, and the source and gate of the silicon carbide device are short-circuited; After each application of a reverse bias voltage to the test group for a first preset time, obtaining current electrical performance parameters of the test group, the current electrical performance parameters of the test group including a current gate leakage current, a current threshold voltage, and a current drain leakage current of the silicon carbide device of the test group; Determining, according to the magnitude of the current electrical performance parameter of the test group, whether the high temperature withstand voltage limit value of the test group is the current reverse bias voltage; Determining whether the high temperature withstand voltage limit value of the test group is the current reverse bias voltage according to the current electrical performance parameter of the test group includes: The silicon carbide device is determined to be a valid device when the current gate leakage current of the silicon carbide device is less than the product of the corresponding initial value and a first preset percentage, and the current drain leakage current is less than the product of the corresponding initial value and the first preset percentage, and the current threshold voltage is within a first preset range, the first preset range represents a range from the product of the initial value corresponding to the threshold voltage and the second preset percentage to the product of the initial value corresponding to the threshold voltage and a sixth preset percentage, and the sixth preset percentage is greater than the second preset percentage; When the current gate leakage current of the silicon carbide device is greater than or equal to the product of the corresponding initial value and the first preset percentage, and / or the current drain leakage current is greater than or equal to the product of the corresponding initial value and the first preset percentage, and / or the current threshold voltage is not within the first preset range, determine that the silicon carbide device is a failed device; When the first failure component ratio is greater than or equal to a third preset percentage, determining the high temperature withstand voltage limit value of the test group to be the last reverse bias voltage, and the first failure component ratio is the ratio of the failure components in the test group; When the proportion of the first failed devices is less than the third preset percentage, continuously applying a reverse bias to the test group based on continuously increasing the reverse bias output by the DC source module; After determining whether the high temperature withstand voltage limit value of the test group is the current reverse bias voltage, the method further includes: Using a plurality of additional silicon carbide devices as a verification group, adjusting the temperature of the high-temperature oven to a preset maximum operating junction temperature, and continuously applying a reverse bias to the verification group based on continuously increasing the reverse bias output by the DC source module; After each application of a reverse bias voltage to the verification group for the first preset time, obtaining again the current electrical performance parameters of the verification group, the current electrical performance parameters of the verification group including the current gate leakage current, the current threshold voltage and the current drain leakage current of the silicon carbide device of the verification group; Whether the high temperature withstand voltage limit value of the test group is valid is determined based on the magnitude of the current electrical performance parameter of the verification group.

2. The method according to claim 1, characterized in that: Determining the high temperature withstand voltage limit value of the test group as the reverse bias voltage of the last time comprises: According to V max =V DSini +(n-1)×∆V d , determine the high temperature withstand voltage limit value of the test group, where V max is the high temperature withstand voltage limit value of the test group, V DSini is the starting value of the reverse bias, ∆V d is a preset step size, n is the current time, the preset step size is the product of the rated operating voltage of the test group and the fifth preset percentage, and the starting value of the reverse bias voltage is the product of the rated operating voltage of the test group and the fourth preset percentage.

3. The method according to claim 1, characterized in that The DC source module includes a DC source and a resistor, the first end of the resistor serves as the first end of the DC source module, the second end of the resistor is electrically connected to the first end of the DC source, and the second end of the DC source is grounded, the current electrical performance parameter of the test group also includes a current resistance value, and in the process of determining whether the high temperature withstand voltage limit value of the test group is the current reverse bias voltage according to the magnitude of the current electrical performance parameter of the test group, the method further includes: In the case where the current gate leakage current of the silicon carbide device is less than the product of the corresponding initial value and a first preset percentage, and the current drain leakage current is less than the product of the corresponding initial value and the first preset percentage, and the current threshold voltage is within a first preset range, and the current resistance value is within a second preset range, the silicon carbide device is determined to be a valid device, the first preset range represents a range from the product of the initial value corresponding to the threshold voltage and the second preset percentage to the product of the initial value corresponding to the threshold voltage and a sixth preset percentage, the sixth preset percentage is greater than the second preset percentage, and the second preset range represents a range from the product of the initial value corresponding to the resistance value and the second preset percentage to the product of the initial value corresponding to the resistance value and the sixth preset percentage; When the current gate leakage current of the silicon carbide device is greater than or equal to the product of the corresponding initial value and the first preset percentage, and / or the current drain leakage current is greater than or equal to the product of the corresponding initial value and the first preset percentage, and / or the current threshold voltage is not within the first preset range, and / or the current resistance value is not within the second preset range, the silicon carbide device is determined to be a failed device.

4. The method according to claim 1, characterized in that: In the process of continuously applying the reverse bias voltage to the test group based on continuously increasing the reverse bias voltage output by the DC source module, the method further includes: When the reverse bias is applied to the test group for the first time, the initial value of the reverse bias is determined to be the product of the rated operating voltage of the test group and a fourth preset percentage.

5. The method according to claim 4, characterized in that Based on continuously increasing the reverse bias voltage output by the DC source module, continuously applying a reverse bias voltage to the test group includes: Reverse bias is continuously applied to the test group based on continuously increasing the reverse bias output by the DC source module with a preset step size, wherein the preset step size is the product of the rated operating voltage of the test group and a fifth preset percentage, and the fifth preset percentage is less than the fourth preset percentage.

6. The method according to claim 1, characterized in that Determining whether the high temperature withstand voltage limit value of the test group is valid according to the magnitude of the current electrical performance parameter of the verification group includes: The silicon carbide device is determined to be a valid device when the current gate leakage current of the silicon carbide device is less than the product of the corresponding initial value and a first preset percentage, and the current drain leakage current is less than the product of the corresponding initial value and the first preset percentage, and the current threshold voltage is within a first preset range, the first preset range represents a range from the product of the initial value corresponding to the threshold voltage and the second preset percentage to the product of the initial value corresponding to the threshold voltage and a sixth preset percentage, and the sixth preset percentage is greater than the second preset percentage; When the current gate leakage current of the silicon carbide device is greater than or equal to the product of the corresponding initial value and the first preset percentage, and / or the current drain leakage current is greater than or equal to the product of the corresponding initial value and the first preset percentage, and / or the current threshold voltage is not within the first preset range, determine that the silicon carbide device is a failed device; In the case where the second failure component ratio is greater than or equal to a third preset percentage, determining that the high temperature withstand voltage limit value of the test group is invalid, the second failure component ratio being the ratio of the failure components in the verification group; When the proportion of the second failed devices is less than the third preset percentage, the high temperature withstand voltage limit value of the test group is determined to be valid, and the reverse bias is continuously applied to the verification group based on continuously increasing the reverse bias output by the DC source module.

7. The method according to claim 1, characterized in that The DC source module includes a DC source and a resistor, a first end of the resistor serves as a first end of the DC source module, a second end of the resistor is electrically connected to the first end of the DC source, and the second end of the DC source is grounded, the current electrical performance parameter also includes a current resistance value, and in the process of determining whether the high temperature withstand voltage limit value of the test group is valid according to the magnitude of the current electrical performance parameter of the verification group, the method further includes: In the case where the current gate leakage current of the silicon carbide device is less than the product of the corresponding initial value and a first preset percentage, and the current drain leakage current is less than the product of the corresponding initial value and the first preset percentage, and the current threshold voltage is within a first preset range, and the current resistance value is within a second preset range, the silicon carbide device is determined to be a valid device, the first preset range represents a range from the product of the initial value corresponding to the threshold voltage and the second preset percentage to the product of the initial value corresponding to the threshold voltage and a sixth preset percentage, the sixth preset percentage is greater than the second preset percentage, and the second preset range represents a range from the product of the initial value corresponding to the resistance value and the second preset percentage to the product of the initial value corresponding to the resistance value and the sixth preset percentage; When the current gate leakage current of the silicon carbide device is greater than or equal to the product of the corresponding initial value and the first preset percentage, and / or the current drain leakage current is greater than or equal to the product of the corresponding initial value and the first preset percentage, and / or the current threshold voltage is not within the first preset range, and / or the current resistance value is not within the second preset range, the silicon carbide device is determined to be a failed device.

8. The method according to claim 1, characterized in that After determining that the high temperature withstand voltage limit value of the test group is invalid, the method further includes: According to V rmax =V max +(n-1)×∆V d , determine the high temperature withstand voltage limit value of the verification group, where V rmax is the high temperature withstand voltage limit value of the verification group, V max is the high temperature withstand voltage limit value of the test group, ∆V d is a preset step length, n is the current time, the preset step length is the product of the rated operating voltage of the test group and the fifth preset percentage, and the starting value of the reverse bias voltage is the product of the rated operating voltage of the verification group and the fourth preset percentage; A final high temperature withstand voltage limit value is determined to be the high temperature withstand voltage limit value of the verification group.

9. The method according to claim 1, characterized in that: In the process of continuously applying the reverse bias voltage to the verification group based on continuously increasing the reverse bias voltage output by the DC source module, the method further includes: In the case where the reverse bias is applied to the verification group for the first time, a starting value of the reverse bias is determined as a product of a rated operating voltage of the verification group and a fourth preset percentage.

10. The method according to claim 9, characterized in that In the process of continuously applying the reverse bias voltage to the verification group based on continuously increasing the reverse bias voltage output by the DC source module, the method further includes: Reverse bias is continuously applied to the verification group based on continuously increasing the reverse bias output by the DC source module with a preset step size, wherein the preset step size is the product of the rated operating voltage of the test group and the fifth preset percentage, and the fifth preset percentage is less than the fourth preset percentage.

11. A system for determining a high temperature withstand voltage limit value of a silicon carbide device, characterized in that: The invention comprises: a silicon carbide device, a high temperature oven and a direct current source module, wherein the high temperature oven is used to place the silicon carbide device, the first end of the direct current source module is used to be electrically connected to the drain of the silicon carbide device, the source and the gate of the silicon carbide device are short-circuited, wherein the silicon carbide device is tested by using the method for determining the high temperature withstand voltage limit value of the silicon carbide device according to any one of claims 1 to 10.

12. The system for determining the high temperature withstand voltage limit value of a silicon carbide device according to claim 11, characterized in that: The DC source module includes a DC source and a resistor, wherein a first end of the resistor serves as a first end of the DC source module, a second end of the resistor is electrically connected to the first end of the DC source, and a second end of the DC source is grounded.

13. The system for determining the high temperature withstand voltage limit value of a silicon carbide device according to claim 11, characterized in that: The silicon carbide device is an insulated gate field effect transistor.

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