Power cycle test method of power device

Abstract

The invention provides a power cycle test method for a power device, and the method comprises the steps: carrying out the initial detection of a to-be-tested power device, obtaining an initial threshold voltage, and carrying out the power cycle test of the to-be-tested power device; under the condition that the to-be-tested power device is turned off in one power cycle and the junction temperature of the to-be-tested power device is reduced to a preset temperature condition, detecting to obtain a test threshold voltage of the to-be-tested power device, and calculating to obtain a threshold voltage change rate according to the initial threshold voltage and the test threshold voltage; and whether the to-be-tested power device is aged and fails is judged according to the threshold voltage change rate. According to the method, characteristic parameters collected in the power cycle process are calibrated in real time, whether a chip fails or not and packaging fails is judged according to parameter deviation values, threshold voltage is accurately tested in the power cycle turn-off process, and then on-line collected conduction voltage drop is calibrated; and synchronous online monitoring of the reliability and the packaging reliability of the silicon carbide chip is realized.

Description

Technical Field

[0001] The present application relates to the field of power cycle testing of power devices, and in particular, to a power cycle testing method for power devices. Background Art

[0002] The power cycle test is the main test method for evaluating the reliability of device packaging. In the power cycle test of silicon carbide metal oxide semiconductor field effect transistor (SiC MOSFET), the device switch is controlled by alternating positive and negative gate stresses, so that the chip intermittently flows with current to generate intermittent heat power, thereby causing the chip temperature to fluctuate. During the temperature fluctuation process of the power cycle, the mismatch of thermal expansion coefficients between packaging materials will cause package-level degradation. On the other hand, SiC MOSFET has a high density of gate oxide interface defects and has serious reliability issues. Alternating positive and negative gate stresses can easily lead to threshold voltage drift, causing changes in channel resistance and on-resistance, making the SiC MOSFET package degradation characteristics more complicated. However, the traditional power cycle test evaluation method cannot accurately characterize the package degradation of power devices and is prone to misjudgment. Summary of the invention

[0003] The main purpose of the present application is to provide a power cycle test method for a power device, so as to at least solve the problem that the traditional power cycle test evaluation method cannot accurately characterize the package degradation of the power device and is prone to misjudgment.

[0004] In order to achieve the objective, according to one aspect of the present application, a power cycle test method for a power device is provided, comprising: performing an initial detection on the power device to be tested to obtain an initial threshold voltage, and performing a power cycle test on the power device to be tested; when the power device to be tested is turned off and the junction temperature of the power device to be tested drops to a preset temperature condition during a power cycle, detecting and obtaining a test threshold voltage of the power device to be tested, and calculating a threshold voltage change rate based on the initial threshold voltage and the test threshold voltage, and judging whether the power device to be tested is aged and failed based on the magnitude of the threshold voltage change rate.

[0005] Optionally, calculating the threshold voltage change rate according to the initial threshold voltage and the test threshold voltage includes: using the initial threshold voltage, the test threshold voltage and a first change rate formula , the threshold voltage change rate is calculated, where, is the threshold voltage change rate, is the test threshold voltage of the i-th power cycle, is the initial threshold voltage.

[0006] Optionally, judging whether the power device to be tested has aged and failed is based on the magnitude of the threshold voltage change rate, including: setting a first preset change rate; determining that the power device to be tested has aged and failed when the threshold voltage change rate is greater than the first preset change rate; and determining that the power device to be tested has not aged and failed when the threshold voltage change rate is less than or equal to the first preset change rate.

[0007] Optionally, the first preset change rate is 4%~6%.

[0008] Optionally, after judging whether the power device to be tested has aged and failed according to the magnitude of the threshold voltage change rate, the method further includes: at least using the test threshold voltage to calculate a test on-state voltage drop; using the test on-state voltage drop and an initial on-state voltage drop to calculate a on-state voltage drop change rate, wherein the initial on-state voltage drop is obtained by performing an initial detection on the power device to be tested; judging whether the power device to be tested has a packaging failure according to the magnitude of the on-state voltage drop change rate.

[0009] Optionally, at least the test threshold voltage is used to calculate the test on-voltage drop, including: using the test threshold voltage and the gate on-voltage of the power device to be tested to calculate the channel resistance of the power device to be tested; when the power device to be tested is turned off in the i-th power cycle and the junction temperature of the power device to be tested drops to the preset temperature condition, the on-resistance of the power device to be tested is detected to obtain the test on-resistance; using the channel resistance, on-current and the test on-resistance to calculate the test on-voltage drop.

[0010] Optionally, the channel resistance, the on-current and the test on-resistance are used to calculate the test on-voltage drop of the power device to be tested, including: using the channel resistance, the on-current, the test on-resistance and the voltage drop formula , the test conduction voltage drop is calculated, where, For the test on-state voltage drop, is the on-resistance of the i-th power cycle, is the channel resistance of the i-th power cycle, is the on-state current.

[0011] Optionally, the test on-state voltage drop and the initial on-state voltage drop are used to calculate the on-state voltage drop change rate, including: using the test on-state voltage drop, the initial on-state voltage drop and the second change rate formula , the on-state voltage drop change rate is calculated, where: is the on-state voltage drop change rate, is the conduction voltage drop of the i-th power cycle, is the initial on-state voltage drop, and the initial on-state voltage drop is obtained by performing initial detection on the power device to be tested.

[0012] Optionally, judging whether the power device to be tested has a packaging failure is based on the magnitude of the on-state voltage drop change rate, including: setting a second preset change rate; determining that the power device to be tested has a packaging failure when the on-state voltage drop change rate is greater than the second preset change rate; and determining that the power device to be tested has not a packaging failure when the on-state voltage drop change rate is less than or equal to the second preset change rate.

[0013] Optionally, the second preset change rate is 4%~6%.

[0014] Applying the technical solution of the present application, the power cycle test method of the power device mentioned above first performs an initial detection on the power device to be tested, obtains the initial threshold voltage, and performs a power cycle test on the power device to be tested; then, when the power device to be tested is turned off in one power cycle and the junction temperature of the power device to be tested drops to a preset temperature condition, the test threshold voltage of the power device to be tested is detected, and the threshold voltage change rate is calculated based on the initial threshold voltage and the test threshold voltage, and whether the power device to be tested is aged and failed is determined based on the magnitude of the threshold voltage change rate. The method calibrates the characteristic parameters collected during the power cycle in real time, determines whether the chip fails and the package fails based on the parameter offset value, accurately tests the threshold voltage during the power cycle shutdown process, and then calibrates the on-state voltage drop collected online, realizes the synchronous online monitoring of the reliability of silicon carbide chips and the reliability of the package, and solves the problem that the traditional power cycle test evaluation method cannot accurately characterize the package degradation of the power device and is prone to misjudgment. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] 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:

[0016] Figure 1 A schematic flow chart of a power cycle test method for a power device provided according to an embodiment of the present application is shown;

[0017] Figure 2 A schematic flow chart of another power cycle test method for a power device provided according to an embodiment of the present application is shown;

[0018] Figure 3 A schematic diagram of the structure of a power cycle test circuit provided according to an embodiment of the present application is shown;

[0019] Figure 4A schematic diagram of the structure of another power cycle test circuit provided according to an embodiment of the present application is shown;

[0020] Figure 5 A schematic diagram of the structure of another power cycle test circuit provided according to an embodiment of the present application is shown;

[0021] Figure 6 A schematic diagram of the structure of an online real-time monitoring system provided according to an embodiment of the present application is shown;

[0022] Figure 7 A flow chart of an online real-time monitoring system provided according to an embodiment of the present application is shown.

[0023] The above drawings include the following reference numerals:

[0024] 11. Power device to be tested; 12. Measurement system; 13. First voltage source; 14. Second voltage source; 15. Power supply module; 16. Test system; 17. Cooling system; 18. Data processing system; 21. Data input module; 22. Judgment module; 23. Data tracking and prediction module. DETAILED DESCRIPTION

[0025] 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.

[0026] 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.

[0027] 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.

[0028] As introduced in the background technology, in the prior art, the channel resistance of SiC MOSFET accounts for about 20% of the on-resistance of the device. Severe threshold voltage drift during power cycling can lead to misjudgment of the on-resistance, affecting the judgment of package degradation. In order to solve the problem that traditional power cycle test evaluation methods cannot accurately characterize the package degradation of power devices and are prone to misjudgment, an embodiment of the present application provides a power cycle test method for a power device.

[0029] 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.

[0030] In this embodiment, a power cycle test method for a power device is provided. It should be noted that although a logical sequence is shown in the flow chart, in some cases, the steps shown or described may be performed in a different order than that shown here.

[0031] Figure 1 FIG. 1 is a flow chart of a power cycle test method for a power device according to an embodiment of the present application. Figure 1 As shown, the method comprises the following steps:

[0032] Step S101, performing an initial test on the power device to be tested, obtaining an initial threshold voltage, and performing a power cycle test on the power device to be tested;

[0033] In some embodiments, it is necessary to perform an initial detection of the threshold voltage and the on-state voltage drop of the power device to be tested under a preset temperature condition to obtain an initial threshold voltage and an initial on-state voltage drop;

[0034] Specifically, SiC MOSFET has a high gate oxide interface defect density and serious reliability issues. The alternating positive and negative gate stresses can easily lead to threshold voltage drift. During the power cycle of power devices, the increase in on-state voltage drop is considered to be bonding degradation, and a change of more than 5% is considered a failure. The channel resistance of SiC MOSFET accounts for about 20% of the device on-state resistance. Severe threshold voltage drift during power cycling can lead to misjudgment of on-state resistance and affect the judgment of package degradation. Traditional power cycle test evaluation methods cannot accurately characterize the package degradation of power devices. For example, the threshold voltage increased due to the power cycle of SiC MOSFET causes the on-state voltage drop Von to increase by more than 5%, which is misjudged as a package failure. However, the threshold voltage decreased due to the power cycle of SiC MOSFET causes the device package failure to not be discovered in time.

[0035] Therefore, in order to solve the above problems, the on-state voltage drop collected online is calibrated during the power cycle shutdown process to achieve simultaneous online monitoring of the chip reliability and package reliability of SiC MOSFET, thereby improving the accuracy of power cycle testing of power devices.

[0036] Before the power cycle test, the threshold voltage, gate leakage, on-resistance, on-voltage drop, and body diode voltage drop of SiC MOSFET were initially measured at room temperature to obtain V GS(th) ,I GSS , R DS(on) 、V DS(on) 、V F , where V GS(th) is the first voltage signal, V DS(on) is the second voltage signal.

[0037] Performing an initial test on the power device under test can ensure that the device is in good condition. At the same time, by comparing the initial test data with the subsequent retest data, it can be determined whether the device has failed.

[0038] Step S102, when the power device to be tested is turned off and the junction temperature of the power device to be tested drops to a preset temperature condition during a power cycle, the test threshold voltage of the power device to be tested is detected, and the threshold voltage change rate is calculated based on the initial threshold voltage and the test threshold voltage, and whether the power device to be tested is aged and failed is determined based on the magnitude of the threshold voltage change rate.

[0039] Specifically, when the device is turned off during the power cycle and the junction temperature drops to room temperature, the threshold voltage, gate leakage, on-resistance, and body diode voltage drop of the SiC MOSFET are measured to be V GS(th)i ,I GSSi , R DS(on)i 、V Fi , calculate the offset value of the first voltage signal to determine whether a chip failure occurs. Power cycling is the process of actively heating the device under test. When the device is turned on, it is the temperature rise stage, and when the device is turned off, it is the temperature drop stage.

[0040] The threshold voltage change rate is calculated based on the initial threshold voltage and the test threshold voltage, including: using the initial threshold voltage, the test threshold voltage and the first change rate formula , the above threshold voltage change rate is calculated, where, is the threshold voltage change rate mentioned above, is the above test threshold voltage of the i-th power cycle, is the initial threshold voltage mentioned above.

[0041] Specifically, the first change rate can be accurately calculated in this way, so as to determine whether the device has aged and failed according to the offset value of the threshold voltage.

[0042] Judging whether the power device to be tested is aged and failed according to the magnitude of the threshold voltage change rate comprises the following steps:

[0043] Step S1021, setting a first preset change rate;

[0044] Step S1022, when the threshold voltage change rate is greater than the first preset change rate, determining that the power device to be tested is aged and failed;

[0045] Step S1023: When the threshold voltage change rate is less than or equal to the first preset change rate, it is determined that the power device to be tested is not aged and failed.

[0046] Specifically, during the temperature fluctuation of the power cycle, the mismatch of thermal expansion coefficients between packaging materials will lead to package-level degradation. On the other hand, SiC MOSFET has a high gate oxide interface defect density and serious reliability issues. The alternation of positive and negative gate stresses can easily lead to threshold voltage drift, causing changes in channel resistance and on-resistance, making the package degradation characteristics of SiC MOSFET more complicated. Therefore, the change rate of the threshold voltage during the heating and cooling process of the SiC device under test can be used to determine whether the power device under test has aged or failed.

[0047] Among them, the above-mentioned first preset change rate is 4%~6%.

[0048] Specifically, the first preset change rate is generally set to 5%. For power cycling of silicon carbide power devices, an increase in on-state voltage drop is considered to be bonding degradation, and a change of more than 5% is considered to be failure. This can accurately determine whether the power device under test has aged and failed.

[0049] After judging whether the power device to be tested is aged and failed according to the magnitude of the threshold voltage change rate, the method further comprises the following steps:

[0050] Step S201, at least using the above test threshold voltage to calculate and obtain a test on-state voltage drop;

[0051] The test on-state voltage drop is obtained by at least using the above test threshold voltage to calculate, and the steps include:

[0052] Step S301, using the test threshold voltage and the gate on-voltage of the power device to be tested, to calculate the channel resistance of the power device to be tested;

[0053] Among them, firstly, the device parameters and on-current of the above-mentioned power device to be tested are tested, and the above-mentioned device parameters include: channel width, channel length, unit area oxide capacitance, electron mobility and gate on-voltage; then, the above-mentioned test threshold voltage and the device parameters of the above-mentioned power device to be tested are used to calculate and obtain the channel resistance of the above-mentioned power device to be tested.

[0054] The test threshold voltage and the device parameters of the power device to be tested are used to calculate the channel resistance of the power device to be tested, including: using the test threshold voltage, the device parameters of the power device to be tested and the resistance calculation formula , the channel resistance of the power device to be tested is calculated, where: is the channel resistance of the power device to be tested, W is the channel width of the power device to be tested, L is the channel length of the power device to be tested, is the above oxide capacitance per unit area, is the above electron mobility, is the gate conduction voltage, is the above test threshold voltage.

[0055] Specifically, in this way, the channel resistance of the power device to be tested during the test process can be accurately obtained, so that the on-state voltage drop of the power device to be tested can be accurately calculated.

[0056] Step S302, when the power device to be tested is turned off and the junction temperature of the power device to be tested drops to the preset temperature condition in the i-th power cycle, the on-resistance of the power device to be tested is detected to obtain a test on-resistance;

[0057] Step S303, using the channel resistance, the on-current and the test on-resistance, calculate and obtain the test on-voltage drop.

[0058] Specifically, in this way, the test on-resistance of the power device to be tested during the test process can be accurately obtained, so that the on-voltage drop of the power device to be tested can be accurately calculated.

[0059] The test on-state voltage drop of the power device to be tested is calculated by using the channel resistance, the on-state current and the test on-state resistance, including: using the channel resistance, the on-state current, the test on-state resistance and the voltage drop formula , the above test conduction voltage drop is calculated, where: For the above test on-state voltage drop, is the above on-resistance of the i-th power cycle, is the above channel resistance of the i-th power cycle, is the above-mentioned on-state current.

[0060] Specifically, in this way, the on-state voltage drop of the power device to be tested can be accurately calculated.

[0061] Step S202, using the test on-state voltage drop and the initial on-state voltage drop to calculate the on-state voltage drop change rate, wherein the initial on-state voltage drop is obtained by performing an initial detection on the power device to be tested;

[0062] The on-state voltage drop change rate is calculated by using the above-mentioned test on-state voltage drop and the above-mentioned initial on-state voltage drop, including: using the above-mentioned test on-state voltage drop, the initial on-state voltage drop and the second change rate formula , the above-mentioned on-state voltage drop change rate is calculated, where, is the above-mentioned on-state voltage drop change rate, is the above conduction voltage drop of the i-th power cycle, is the above-mentioned initial on-state voltage drop, which is obtained by performing initial detection on the power device to be tested.

[0063] Specifically, the second change rate can be accurately calculated in this way, so as to determine whether a packaging failure occurs in the device according to the offset value of the on-state voltage drop.

[0064] Step S203 , judging whether the packaging of the power device to be tested fails according to the magnitude of the on-state voltage drop change rate.

[0065] Specifically, a failure criterion calibration method is used to calibrate the characteristic parameters collected during the power cycle in real time, and determine whether the device has chip failure and package failure based on the parameter offset value. The threshold voltage is accurately tested during the power cycle shutdown process, and the on-state voltage drop collected online is calibrated to achieve synchronous online monitoring of the chip reliability and package reliability of SiC MOSFET.

[0066] In addition, the threshold voltage change rate calculated by the initial threshold voltage and the test threshold voltage in the above steps can accurately determine whether the power device to be tested is aged and failed, while the prior art does not take into account the influence of the threshold voltage on the aging and failure of the power device to be tested. Therefore, the above steps take into account the influence of the threshold voltage, and can make a more accurate judgment on the aging and failure of the power device to be tested. Furthermore, the threshold voltage will also affect the packaging failure test of the device. The prior art also does not take into account the influence of the threshold voltage on the packaging failure test of the device. In the above steps of this embodiment, the test conduction voltage drop can be calculated by testing the threshold voltage, and then the conduction voltage drop change rate is calculated by testing the conduction voltage drop and the initial conduction voltage drop to evaluate the packaging failure of the power device to be tested, that is, the means of testing the threshold voltage used in the above embodiment to improve the aging and failure test of the device is simultaneously used in the packaging failure test of the device, so that the accuracy of the packaging failure of the device is greatly improved.

[0067] Wherein, judging whether the power device to be tested has packaging failure according to the magnitude of the on-state voltage drop change rate comprises the following steps:

[0068] Step S2031, setting a second preset change rate;

[0069] Step S2032, when the on-state voltage drop change rate is greater than the second preset change rate, determining that the package of the power device to be tested is failed;

[0070] Step S2033: when the on-state voltage drop change rate is less than or equal to the second preset change rate, it is determined that the power device to be tested is not packaged and has failed.

[0071] Specifically, during the temperature fluctuation of the power cycle, the mismatch of thermal expansion coefficients between packaging materials will lead to package-level degradation. On the other hand, SiC MOSFET has a high gate-oxide interface defect density and serious reliability issues. The alternation of positive and negative gate stresses can easily lead to threshold voltage drift, causing changes in channel resistance and on-resistance, making the package degradation characteristics of SiC MOSFET more complicated. Therefore, the rate of change of on-voltage drop during the heating and cooling process of the power device under test can be used to determine whether the package of the power device under test has failed.

[0072] Among them, the above-mentioned second preset change rate is 4%~6%.

[0073] Specifically, the second preset change rate is generally 5%. For power cycling of silicon carbide power devices, an increase in on-state voltage drop is considered to be bonding degradation, and a change of more than 5% is considered to be a failure. It can accurately determine whether a packaging failure occurs in the power device to be tested.

[0074] The power cycle test method of the power device of the present application first performs an initial detection on the power device to be tested, obtains the initial threshold voltage, and performs a power cycle test on the power device to be tested; then, when the power device to be tested is turned off in one power cycle and the junction temperature of the power device to be tested drops to a preset temperature condition, the test threshold voltage of the power device to be tested is detected, and the threshold voltage change rate is calculated based on the initial threshold voltage and the test threshold voltage, and whether the power device to be tested is aged and failed is determined based on the magnitude of the threshold voltage change rate. The method calibrates the characteristic parameters collected during the power cycle in real time, determines whether the chip fails and the package fails based on the parameter offset value, accurately tests the threshold voltage during the power cycle shutdown process, and then calibrates the on-state voltage drop collected online, realizes the synchronous online monitoring of the reliability of silicon carbide chips and the reliability of the package, and solves the problem that the traditional power cycle test evaluation method cannot accurately characterize the package degradation of the power device and is prone to misjudgment.

[0075] In order to enable those skilled in the art to more clearly understand the technical solution of the present application, the implementation process of the power cycle test method for a power device of the present application will be described in detail below in conjunction with specific embodiments.

[0076] This embodiment relates to a specific power cycle test method for a power device, such as Figure 2As shown, the following steps are included:

[0077] Step S1: Before the power cycle test, the threshold voltage, gate leakage, on-resistance, on-voltage drop, and body diode voltage drop of the SiC MOSFET are initially measured to obtain V GS(th)0 ,I GSS0 , R DS(on)0 、V DS(on)0 、V F0 , where V GS(th)0 is the first voltage signal, V DS(on)0 is the second voltage signal, and the channel resistance R is calculated according to the measured first voltage signal. CHi , obtain a calibrated third voltage signal.

[0078] Step S2: Under the condition of device off in power cycle, the threshold voltage, gate leakage, on-resistance and body diode voltage drop of SiC MOSFET are measured as V GS(th)i ,I GSSi , R DS(on)i 、V Fi , calculate the first voltage signal offset value to determine whether a chip failure occurs.

[0079] Step S3: Based on the measured V GS(th)i Calculating Channel Resistance .

[0080] Step S4: Calculate the on-state voltage drop calibration value: , V DSi The third voltage signal is used to calculate the on-state voltage drop calibration offset value to determine whether a package failure occurs.

[0081] It should be noted that the steps shown in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and that, although a logical order is shown in the flowcharts, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0082] The present application also provides a power cycle test circuit. Figure 3 As shown, including:

[0083] A power device 11 to be tested, using any of the above-mentioned power cycle test methods for power devices to perform a failure test on the above-mentioned power device 11 to be tested;

[0084] The measuring system 12 is electrically connected to the drain, gate and source of the power device 11 to be tested, and is used to detect the working parameters of the power device 11 to be tested;

[0085] A first voltage source 13, electrically connected to the gate and source of the power device 11 to be tested, respectively, for providing the power device 11 to be tested with a voltage required for testing;

[0086] The second voltage source 14 is electrically connected to the gate and drain of the power device 11 to be tested, respectively, and is used to provide the power device 11 to be tested with a voltage required for testing.

[0087] The power cycle test circuit of the present application includes: a power device to be tested, using any power cycle test method for a power device to perform a failure test on the power device to be tested; a measurement system, electrically connected to the drain, gate and source of the power device to be tested, respectively, for detecting the working parameters of the power device to be tested; a first voltage source, electrically connected to the gate and source of the power device to be tested, respectively, for providing the power device to be tested with the voltage required for the test; a second voltage source, electrically connected to the gate and drain of the power device to be tested, respectively, for providing the power device to be tested with the voltage required for the test. The circuit integrates power cycle reliability testing, parameter testing and calibration into a power cycle test circuit topology and device design, and evaluates the device aging during the power cycle test.

[0088] The measurement system is respectively connected to the drain, source and drain, the first voltage signal is the threshold voltage of the device, and the second voltage signal is the on-state voltage drop of the device. The first voltage source is used to provide a source gate voltage to the power device to be measured, and the second voltage source is used to provide a gate-drain voltage to the power device to be measured.

[0089] Among them, Figure 4 As shown, the power cycle test circuit further includes a power supply module 15 .

[0090] In one embodiment, Figure 4 The figure shows a schematic diagram of the structure of a power cycle test circuit for power cycle reliability test, parameter test and calibration in an embodiment, and a SiC MOSFET power cycle test is carried out:

[0091] Step 1: Perform an initial test on the SiC MOSFET before power cycling test to obtain V GS(th)0 and V DS(on)0 , where V GS(th)0 is the first voltage signal, V DS(on)0 is the second voltage signal. The first voltage signal is measured to be 2.8V, the second voltage signal is measured to be 1.5V, and the third voltage signal is calculated to be 1.42V.

[0092] Step 2: In the 5000th power cycle, the first voltage signal is measured to be 2.9 V and the second voltage signal is measured to be 1.65 V under the device off condition. The calculated first voltage signal offset value of 0.1 V does not exceed the failure criterion, and the chip does not fail.

[0093] Step 3: Based on the measured V GS(th)5000 The channel resistance RCHi is calculated, and the third voltage signal is calculated to be 1.51. The offset value exceeds 5%, which is determined to be a package failure.

[0094] In some instances, such as Figure 5 As shown, the power cycle test circuit also includes: a test system 16, which is electrically connected to the gate, drain and source of the power device 11 under test, respectively, and is used to provide a test signal to the power device 11 under test and control the power device 11 under test to operate in a preset state.

[0095] Specifically, the test system is connected to the gate, drain and source of the device under test respectively, and is used to provide a test signal to the device and control it to work in a preset state, automatically controlling the device to turn on and off to achieve specified test conditions.

[0096] In some instances, such as Figure 5 As shown, the power cycle test circuit also includes:

[0097] A cooling system 17, used for cooling the power device 11 under test;

[0098] The data processing system 18 is used to record test data, where the test data at least includes test time, test temperature, and operating parameters of the power device 11 to be tested.

[0099] Specifically, the cooling system includes forced air and water cooling devices, and the choice of cooling method depends on the test sample and the test requirements; the data processing system records relevant test data, including temperature, test time, electrical parameter test information, first and second voltage signal results, calibrates to obtain the third voltage signal, and determines whether a packaging failure occurs based on the third voltage signal.

[0100] The present application also provides an online real-time monitoring system. Figure 6 As shown, including:

[0101] A data input module 21, used to control the power device to be tested to work in a preset state and obtain the working parameters and test parameters of the power device to be tested. The power device to be tested is a device that is tested for failure using any of the power cycle test methods for the power device described above;

[0102] The judgment module 22 is electrically connected to the data input module 21 and is used to judge the failure of the device and determine the failure mechanism of the SiC MOSFET.

[0103] The online real-time monitoring system of the present application includes: a data input module, which is used to control the power device to be tested to work in a preset state, and obtain the working parameters and test parameters of the power device to be tested, and the power device to be tested is a device that adopts any of the power cycle test methods of the power device to perform failure test; a judgment module, which is electrically connected to the data input module, and is used to judge the failure of the device and determine the failure mechanism of the SiC MOSFET. The online real-time monitoring system is an online real-time monitoring system suitable for power cycle testing of power devices, which tracks the health status of the device in real time and improves the accuracy of power cycle testing of power devices.

[0104] The data input module is used to control the device under test to work in a preset state, obtain the first voltage signal and the second voltage signal, and calibrate and obtain the third voltage signal. The judgment module is connected to the above-mentioned measurement module, and is used to judge the failure of the above-mentioned device, and determine the failure mechanism of the above-mentioned SiC MOSFET according to the above-mentioned first voltage signal and the above-mentioned third voltage signal.

[0105] In some instances, such as Figure 6 As shown, the online real-time monitoring system also includes: a data tracking and prediction module 23, which is used to monitor the device status of the above-mentioned power device to be tested in real time, and fit the parameter change law, obtain the relationship between the initial parameter change law and the failure mode, statistically analyze the probability of aging failure and packaging failure, and predict the failure mode according to the above-mentioned initial parameter change law.

[0106] Specifically, the data tracking and prediction module records the first voltage signal, the second voltage signal measured in previous power cycles and the third voltage signal obtained by calibration, tracks the health status of the device in real time, fits the parameter change law, obtains the relationship between the initial parameter change law and the failure mode, counts the occurrence probabilities of the two failure modes, and predicts the failure mode based on the initial parameter change law.

[0107] Figure 7 It is a flow chart of an online real-time monitoring system. Figure 7 As shown, first, the data input module controls the device under test to work in a preset state, obtains the first voltage signal, the second voltage signal, and calibrates to obtain the third voltage signal. Then, the judgment module determines the failure mechanism of the SiC MOSFET according to the first voltage signal and the third voltage signal. Finally, the data tracking and prediction module tracks the health status of the device in real time according to the first voltage signal, the second voltage signal measured by the recorded power cycle and the third voltage signal obtained by calibration, fits the parameter change law, and calculates the probability of occurrence of the two failure modes to predict the device failure mode.

[0108] Example

[0109] Select several devices to carry out power cycle tests, record the first voltage signal, second voltage signal and third voltage signal obtained by calibration in previous power cycles, fit the parameter change law, and statistically analyze the probability of two failure modes. The obtained law is: if the first voltage signal drifts within the first 24 hours, and its change rate exceeds 1%, and the change rate of the second voltage signal does not exceed 1% within 48 hours, the final failure mode is chip failure; if the first voltage signal does not drift by more than 1% within the first 24 hours, and the second voltage signal does not drift by more than 1% within 48 hours, the final failure mode is package failure. According to the obtained law, the failure mode of the device can be determined based on the first voltage signal, the second voltage signal and the third voltage signal obtained by calibration within 48 hours before the power cycle.

[0110] The above embodiment proposes a power cycle test method for power devices. A failure criterion calibration method is used to calibrate the characteristic parameters collected during the power cycle in real time, and determine whether the device has chip failure and package failure based on the parameter offset value. A power cycle test circuit topology and device design that integrates power cycle reliability testing and parameter testing and calibration is proposed to evaluate the aging of devices during the power cycle test. In addition, an online real-time monitoring system suitable for power cycle testing of power devices is also proposed to track the health status of the device in real time and improve the accuracy of power cycle testing of power devices.

[0111] The embodiment of the present application also provides a power cycle test device for a power device. It should be noted that the power cycle test device for a power device in the embodiment of the present application can be used to execute the power cycle test method for a power device provided in the embodiment of the present application. The device is used to implement the above-mentioned embodiments and preferred implementation modes, and the descriptions that have been made will not be repeated. As used below, the term "module" can implement a combination of software and / or hardware for a predetermined function. Although the device described in the following embodiments is preferably implemented in software, the implementation of hardware, or a combination of software and hardware, is also possible and conceived.

[0112] 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.

[0113] From the above description, it can be seen that the above embodiments of the present application achieve the following technical effects:

[0114] The power cycle test method of the power device of the present application first performs an initial detection on the power device to be tested, obtains the initial threshold voltage, and performs a power cycle test on the power device to be tested; then, when the power device to be tested is turned off in one power cycle and the junction temperature of the power device to be tested drops to a preset temperature condition, the test threshold voltage of the power device to be tested is detected, and the threshold voltage change rate is calculated based on the initial threshold voltage and the test threshold voltage, and whether the power device to be tested is aged and failed is determined based on the magnitude of the threshold voltage change rate. The method calibrates the characteristic parameters collected during the power cycle in real time, determines whether the chip fails and the package fails based on the parameter offset value, accurately tests the threshold voltage during the power cycle shutdown process, and then calibrates the on-state voltage drop collected online, realizes the synchronous online monitoring of the reliability of silicon carbide chips and the reliability of the package, and solves the problem that the traditional power cycle test evaluation method cannot accurately characterize the package degradation of the power device and is prone to misjudgment.

[0115] 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 power cycle test method for a power device, characterized in that: include: Performing an initial detection on the power device to be tested to obtain an initial threshold voltage, and performing a power cycle test on the power device to be tested; When the power device to be tested is turned off and the junction temperature of the power device to be tested drops to a preset temperature condition during a power cycle, the test threshold voltage of the power device to be tested is detected, and the threshold voltage change rate is calculated based on the initial threshold voltage and the test threshold voltage, and whether the power device to be tested has aged and failed is determined based on the magnitude of the threshold voltage change rate.

2. The method according to claim 1, characterized in that The threshold voltage change rate is calculated according to the initial threshold voltage and the test threshold voltage, including: Using the initial threshold voltage, the test threshold voltage and the first change rate formula , the threshold voltage change rate is calculated, where, is the threshold voltage change rate, is the test threshold voltage of the i-th power cycle, is the initial threshold voltage.

3. The method according to claim 1, characterized in that Judging whether the power device to be tested is aged and failed according to the magnitude of the threshold voltage change rate includes: Setting a first preset change rate; When the threshold voltage change rate is greater than the first preset change rate, determining that the power device to be tested has aged and failed; When the threshold voltage change rate is less than or equal to the first preset change rate, it is determined that the power device to be tested has not aged and failed.

4. The method according to claim 3, characterized in that: The first preset change rate is 4%~6%.

5. The method according to claim 1, characterized in that After determining whether the power device to be tested is aged and failed according to the magnitude of the threshold voltage change rate, the method further includes: At least the test threshold voltage is used to calculate the test on-state voltage drop; The test on-state voltage drop and the initial on-state voltage drop are used to calculate the on-state voltage drop change rate, wherein the initial on-state voltage drop is obtained by performing an initial detection on the power device to be tested; Whether the power device to be tested has packaging failure is determined according to the magnitude of the on-state voltage drop change rate.

6. The method according to claim 5, characterized in that At least using the test threshold voltage to calculate the test on-state voltage drop includes: The test threshold voltage and the gate on-voltage of the power device to be tested are used to calculate the channel resistance of the power device to be tested; When the power device to be tested is turned off in the i-th power cycle and the junction temperature of the power device to be tested drops to the preset temperature condition, detecting the on-resistance of the power device to be tested to obtain a test on-resistance; The test on-voltage drop is calculated by using the channel resistance, the on-current and the test on-resistance.

7. The method according to claim 6, characterized in that The test on-state voltage drop of the power device to be tested is calculated by using the channel resistance, the on-state current and the test on-state resistance, including: Using the channel resistance, the on-current, the test on-resistance and the voltage drop formula , the test conduction voltage drop is calculated, where, For the test on-state voltage drop, is the on-resistance of the i-th power cycle, is the channel resistance of the i-th power cycle, is the on-state current.

8. The method according to claim 5, characterized in that The on-state voltage drop change rate is calculated using the test on-state voltage drop and the initial on-state voltage drop, including: Using the test conduction voltage drop, initial conduction voltage drop and second change rate formula , the on-state voltage drop change rate is calculated, where: is the on-state voltage drop change rate, is the conduction voltage drop of the i-th power cycle, is the initial on-state voltage drop, and the initial on-state voltage drop is obtained by performing initial detection on the power device to be tested.

9. The method according to claim 5, characterized in that Judging whether the power device to be tested has packaging failure according to the magnitude of the on-state voltage drop change rate includes: Setting a second preset rate of change; When the on-state voltage drop change rate is greater than the second preset change rate, determining that the package of the power device to be tested has failed; When the on-state voltage drop change rate is less than or equal to the second preset change rate, it is determined that the power device to be tested has not been packaged and failed.

10. The method according to claim 9, characterized in that The second preset change rate is 4%~6%.

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