A Temperature Interaction Identification Method for Threshold Voltage Degradation of Silicon Carbide Power MOSFETs

Abstract

A method for identifying the temperature interaction of threshold voltage degradation of silicon carbide power MOSFET belongs to the technical field of reliability identification of electronic components. In order to solve the problem that there is no temperature interaction analysis method for threshold voltage degradation of silicon carbide power MOSFET in the prior art, the present invention first conducts an accelerated degradation test to obtain threshold voltage degradation data for temperature interaction identification, then eliminates abnormal measurement fluctuations and measurement errors, and performs a temperature T in a constant temperature accelerated degradation test. i With T j The method is used to identify temperature interactions in MOSFET threshold voltage degradation.

Description

Technical Field

[0001] The present invention belongs to the technical field of electronic component reliability identification, and in particular relates to a temperature interaction identification method for voltage degradation of an electronic semiconductor device. Background Art

[0002] As a key semiconductor device in modern electronic devices, silicon carbide power MOSFETs (insulated gate field-effect transistors) play a vital role. Their superior switching characteristics and low on-resistance make them ideal for high-efficiency power management and signal processing, and they are widely used in power conversion, motor drives, lighting control, and electric vehicles. With the development of intelligent and automated technologies, the application of silicon carbide power MOSFETs in power electronics systems is becoming increasingly important, and their performance degradation directly affects the reliable operation of equipment and systems.

[0003] Currently, the research on the impact of threshold voltage degradation on SiC power MOSFETs is incomplete, resulting in poor prediction of MOSFET threshold voltage degradation. Summary of the Invention

[0004] The present invention aims to solve the problem that the prior art lacks a temperature interaction analysis method for threshold voltage degradation of silicon carbide power MOSFETs.

[0005] A method for identifying temperature interaction of threshold voltage degradation of a silicon carbide power MOSFET, comprising:

[0006] Step 1: Conduct accelerated degradation testing on SiC power MOSFETs to obtain threshold voltage degradation data for temperature interaction identification. The specific process includes the following steps:

[0007] Step 11: Determine the MOSFET's turn-on signal voltage, turn-off signal voltage, and signal frequency based on the actual drive signal parameters of the MOSFET in the circuit; and determine the accelerated degradation test temperature range;

[0008] Step 12: Set n groups of constant temperature accelerated degradation tests; set the voltage and frequency of the MOSFET on / off signals in each group to be the same according to step 11; in the test, the drain and source of the MOSFET are short-circuited, and the drive signal is applied only to the gate; select n temperatures within the accelerated degradation test temperature range, and record them as T1 to T2. n ;

[0009] Step 13: Design the duration and frequency of the constant temperature accelerated degradation test and conduct the test;

[0010] Step 14: At T1 to T n Select two temperatures T i With T j;

[0011] Step 15: Set up two groups of two-stage temperature accelerated degradation tests; in the two-stage temperature accelerated degradation test group 1, first apply T i , then apply T j ; In the two-stage temperature accelerated degradation test group 2, T j , then apply T i ;Other test settings are the same as S12;

[0012] Step 16: Design the duration and test frequency of the two-stage temperature accelerated degradation test, and conduct the two-stage temperature accelerated degradation test;

[0013] Step 2: Process the threshold voltage degradation data obtained in step 1 by fitting and smoothing methods;

[0014] The temperature in the constant temperature accelerated degradation test is T i With T j The sample data of each group and the sample data of each group in the second stage of the two-stage temperature accelerated degradation test are fitted respectively:

[0015] V th (t)=a1·exp(a2·t)+a3·exp(a4·t) (1)

[0016] Among them, V th (t) is the value of the threshold voltage at time t, a1, a2, a3, and a4 are parameters that need to be determined by fitting;

[0017] Step 3: Perform statistical tests on the processed degradation path data and determine whether the degradation is affected by temperature interaction based on the statistical test results.

[0018] Furthermore, in step 1, it is necessary to determine the accelerated degradation test temperature range. In this process, the temperature operating range specified in the MOSFET parameter manual is determined as the accelerated degradation test temperature range.

[0019] Furthermore, the test duration designed in step 13 should ensure that the mean threshold voltage of the test samples in each group can degrade by more than 10% of the mean initial value.

[0020] Furthermore, the test frequency designed in step 13 should ensure that the number of tests for each group during the test period is greater than 10 times.

[0021] Furthermore, the process of designing the duration and test frequency of the two-stage temperature accelerated degradation test and conducting the two-stage temperature accelerated degradation test in step 16 includes the following steps:

[0022] In the two-stage temperature accelerated degradation test group 1, T i, when the threshold voltage mean of the test sample degrades by P% of the initial mean, the application duration is t s1 T j ;

[0023] In the two-stage temperature accelerated degradation test group 2, T j , when the threshold voltage mean of the test sample degrades by P% of the initial mean, the application duration is t s2 T j .

[0024] Furthermore, the P% is set to 5%.

[0025] Furthermore, the application time of the second stage temperature of the two-stage temperature accelerated degradation test group 1 and the two-stage temperature accelerated degradation test group 2 should ensure that at least 10 test points can be obtained in each group.

[0026] Furthermore, the specific process of step 3 includes the following steps:

[0027] Step 31: Calculate the average threshold voltage degradation V of the test samples in Group 1 and Group 2 at the end of the first stage of the two-stage temperature accelerated degradation test. th1 and V th2 .

[0028] Step 32: Determine the average degradation of samples in G1 as V th1 The time is recorded as t1, and the average degradation of samples in G2 is determined to be V th2 The time is recorded as t2;

[0029] Step 33: After time t1 in G1, the time length is t s1 The degradation curve of each sample is recorded as S1; after time t2 in G2, the time length is t s2 The degradation curve of each sample is recorded as S2;

[0030] Among them, G1 is the temperature T in the constant temperature accelerated degradation test in step 2. j The degradation curves of each sample obtained by the group are shown in Figure 2. G2 is the temperature T in the constant temperature accelerated degradation test fitted in step 2. i The degradation curves of each sample obtained by the group;

[0031] Step 34: Perform a Mann-Whitney U test on the degradation data of groups S1 and C1 at the same time, and perform a Mann-Whitney U test on the degradation data of groups S2 and C2 at the same time to obtain two p-value curves. Determine the distribution difference of the corresponding two groups of samples based on the p in the curves, and then determine the temperature level interaction.

[0032] Wherein, C1 is the degradation curve of each sample obtained by fitting the two-stage temperature accelerated degradation test group 1 in step 2, and C2 is the degradation curve of each sample obtained by fitting the two-stage temperature accelerated degradation test group 2 in step 2.

[0033] Furthermore, the distribution difference between the two groups of samples is determined according to p in the curve, and in the process of determining the interaction between the temperature levels, the distribution difference between the two groups of samples corresponding to the part of the curve where p < the discrimination threshold is different, that is, there is a temperature level interaction.

[0034] Furthermore, the discrimination threshold is 0.05.

[0035] Effects of the invention:

[0036] This invention provides an effective solution for determining whether silicon carbide power MOSFETs are subject to temperature interactions and thus deviate from their degradation paths under dynamic temperatures. It accurately identifies potential temperature interactions and can contribute to the development of new degradation accumulation calculation methods and improve the accuracy of reliability prediction. The invention can quantify the extent to which threshold voltage degradation is affected by temperature interactions and is applicable to a wide range of electronic component types. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is the flow chart of temperature interaction identification of MOSFET threshold voltage degradation;

[0038] Figure 2 This is a graph showing the data of a constant temperature accelerated degradation test in the embodiment;

[0039] Figure 3 2. It is a graph of the data of the two-stage temperature accelerated degradation test in the embodiment;

[0040] Figure 4 is a temperature interaction identification diagram of the two-stage temperature group 1 in the embodiment;

[0041] Figure 5 1 is a temperature interaction identification diagram of the two-stage temperature group 2 in the embodiment. DETAILED DESCRIPTION

[0042] During research on the reliability of silicon carbide power MOSFETs, the present inventors discovered that silicon carbide power MOSFETs typically operate under complex and variable temperature conditions. Accurately estimating degradation requires determining whether interactions exist between different temperature levels, which can significantly impact degradation pathways. Therefore, a method for identifying temperature interactions in threshold voltage degradation of silicon carbide power MOSFETs was proposed. This method is described in detail below, along with specific implementations.

[0043] Specific implementation method 1: Combination Figure 1 To explain this embodiment,

[0044] This embodiment provides a method for identifying temperature interaction of threshold voltage degradation of a silicon carbide power MOSFET, specifically comprising the following steps:

[0045] Step 1: Conduct accelerated degradation testing on SiC power MOSFETs to obtain threshold voltage degradation data for temperature interaction identification. The specific process includes the following steps:

[0046] Step 11: Determine the MOSFET's turn-on signal voltage, turn-off signal voltage, and signal frequency based on the actual drive signal parameters of the MOSFET in the circuit; and determine the temperature operating range specified in the MOSFET parameter manual as the accelerated degradation test temperature range.

[0047] Step 12: Set n groups (n≥2) of constant temperature accelerated degradation tests. According to step 11, set the voltage and frequency of the MOSFET on / off signals in each group to be the same, as shown in Table 1. Select n temperatures (T1, ..., T2) in the accelerated degradation test temperature range determined in step S11. n In the test, the drain and source of the MOSFET are short-circuited, and the driving signal is applied only to the gate.

[0048] Table 1 Constant temperature accelerated degradation test settings

[0049] experimental group Accelerated test stress setting Constant temperature group 1 <![CDATA[Turn-on signal voltage V1, turn-off signal voltage V2, signal frequency f, temperature T1]]> Constant temperature group 2 <![CDATA[Turn-on signal voltage V1, turn-off signal voltage V2, signal frequency f, temperature T2]]> …… …… Constant temperature group n <![CDATA[Turn-on signal voltage V1, turn-off signal voltage V2, signal frequency f, temperature T n >

[0050] Step 13: Design the duration and test frequency of the constant temperature accelerated degradation test and conduct the test.

[0051] The test duration should ensure that the mean threshold voltage of the test samples in each group can degrade by more than 10% of the initial mean value.

[0052] The test frequency should ensure that the number of tests per group during the test period is greater than 10 times.

[0053] Step 14: At T1,…,T n Select two temperatures T i With T j , T i With T j The greater the difference in the threshold voltage degradation paths under the constant temperature accelerated degradation test, the more conducive it is to the identification of temperature interaction.

[0054] Step 15: Set up two sets of two-stage temperature accelerated degradation tests. In the two-stage temperature accelerated degradation test set 1, first apply T i , then apply T j In the two-stage temperature accelerated degradation test group 2, T j , then apply T i The other experimental settings are the same as those of S12.

[0055] Step 16: Design the duration and test frequency of the two-stage temperature accelerated degradation test and conduct the test. i , when the threshold voltage mean of the test sample degrades by about 5% of the initial mean, the application duration is t s1 T j In the two-stage temperature accelerated degradation test group 2, T j , when the threshold voltage mean of the test sample degrades by about 5% of the initial mean, the application duration is t s2 T j The application time of the second stage temperature should ensure that at least 10 test points can be obtained in each group.

[0056] Step 2: Process the threshold voltage degradation data obtained in step 1 by fitting and smoothing methods to eliminate abnormal measurement fluctuations and measurement errors;

[0057] The temperature in the constant temperature accelerated degradation test is T i With T j The sample data of each group and the sample data of each group in the second stage of the two-stage temperature accelerated degradation test are fitted respectively:

[0058] V th (t)=a1·exp(a2·t)+a3·exp(a4·t) (1)

[0059] Among them, V th (t) is the value of the threshold voltage at time t, and a1, a2, a3, and a4 are parameters that need to be determined through fitting.

[0060] The degradation curves of each sample obtained by fitting the two-stage temperature accelerated degradation test group 1 are recorded as C1, and the degradation curves of each sample obtained by fitting the two-stage temperature accelerated degradation test group 2 are recorded as C2. j The degradation curve of each sample obtained by the group is recorded as G1, and the temperature in the constant temperature accelerated degradation test is T i The degradation curve of each sample obtained by the group is recorded as G2.

[0061] Step 3: Perform a statistical test on the degradation path data after S2 processing, and determine whether the degradation is affected by temperature interaction based on the statistical test results. The specific process includes the following steps:

[0062] Step 31: Calculate the average threshold voltage degradation V of the test samples in the two-stage temperature accelerated degradation test group 1 and the two-stage temperature accelerated degradation test group 2 at the end of the first stage of the two-stage temperature accelerated degradation test. th1 and V th2 .

[0063] Step 32: Determine the average degradation of samples in G1 as V th1 The time is recorded as t1, and the average degradation of samples in G2 is determined to be V th2 The time is recorded as t2.

[0064] Step 33: After time t1 in G1, the time length is t s1 The degradation curve of each sample is recorded as S1; after time t2 in G2, the time length is t s2 The degradation curve of each sample is recorded as S2.

[0065] Step 34: Perform a Mann-Whitney U test on the degradation data of groups S1 and C1 at the same time, and perform a Mann-Whitney U test on the degradation data of groups S2 and C2 at the same time, and obtain two p-value curves. The portion of the curve where p < the discrimination threshold (0.05 in this embodiment) corresponds to a significant difference in the distribution of the two groups of samples, that is, there is a temperature level interaction.

[0066] It should be noted that: this embodiment is for silicon carbide power MOSFET, and the identification threshold is determined to be 0.05. In fact, the present invention can also be used for temperature interaction identification of threshold voltage degradation of other components, and the specific identification threshold is determined according to actual conditions.

[0067] Example:

[0068] This embodiment uses a certain type of silicon carbide NMOSFET as an object for temperature interaction identification, and its operating temperature is -55°C to +150°C.

[0069] Step 1: Conduct accelerated degradation tests to obtain threshold voltage degradation data for temperature interaction identification.

[0070] Step 11: Determine the MOSFET's turn-on signal voltage, turn-off signal voltage, and signal frequency based on the actual drive signal parameters of the MOSFET in the circuit, which are 20V, -5V, and 100kHz, respectively; and determine the temperature operating range specified in the MOSFET parameter manual as the accelerated degradation test temperature range, which is -55°C to +150°C.

[0071] Step 12: Set up two constant temperature accelerated degradation tests. The specific stress settings are shown in Table 2. In the tests, the drain and source of the MOSFET are short-circuited, and the drive signal is applied only to the gate. Each group has 10 MOSFETs.

[0072] Table 2 Constant temperature accelerated degradation test settings

[0073]

[0074] Step 13: Design a constant temperature accelerated degradation test for 3000 hours. The average of the two threshold voltages can degrade by more than 10% of the initial average. The test is measured every 20 hours. The test results are as follows: Figure 2 shown.

[0075] Step 14: T i =25℃, T j =120℃.

[0076] Step 15: Set up two sets of two-stage temperature accelerated degradation tests. In the two-stage temperature accelerated degradation test set 1, first apply T i , then apply T j In the two-stage temperature accelerated degradation test group 2, T j , then apply T i The other test settings are the same as S12, with 10 MOSFETs in each group.

[0077] Step 16: Also with 20 hours as the test interval, Group 1 first applies 25°C. After 1120 hours, the average threshold voltage degradation of the test samples reaches 5% of the initial average value. Then, the application duration is t s1 = 120℃ for 880 hours. In group 2, 120℃ was first applied, and the threshold voltage average degradation of the test samples reached 5% of the initial average value after 200 hours. Then the application duration was t s2 = 800 hours at 25°C, the results are as follows Figure 3 shown.

[0078] Step 2: The threshold voltage degradation data obtained in step 1 is processed by fitting and smoothing methods to eliminate abnormal measurement fluctuations and measurement errors.

[0079] The temperature in the constant temperature accelerated degradation test is T i With T j Fit the data of each group of samples and each group of samples in the second stage of the two-stage temperature accelerated degradation test:

[0080] V th (t)=a1·exp(a2·t)+a3·exp(a4·t) (2)

[0081] Among them, V th (t) is the value of the threshold voltage at time t, and a1, a2, a3, and a4 are parameters that need to be determined by fitting. The degradation curves of each sample obtained by fitting the two-stage temperature accelerated degradation test group 1 are recorded as C1, and the degradation curves of each sample obtained by fitting the two-stage temperature accelerated degradation test group 2 are recorded as C2. The temperature in the constant temperature accelerated degradation test is T j=120℃ group degradation curves of each sample are recorded as G1, and the temperature in the constant temperature accelerated degradation test is T i =25℃ group degradation curves of each sample are recorded as G2.

[0082] Step 3: Perform statistical tests on the processed degradation path data and determine whether the degradation is affected by temperature interaction based on the statistical test results:

[0083] Step 31: Calculate the average threshold voltage degradation V of the test samples in Group 1 and Group 2 at the end of the first stage of the two-stage temperature accelerated degradation test. th1 =4.59V and V th2 =4.49V.

[0084] Step 32: The average degradation of samples in G1 is V th1 The time is recorded as t1 = 149 hours, and the average degradation of the samples in G2 is V th2 The time is recorded as t2 = 301 hours.

[0085] Step 33: After time t1=149 hours in G1, the time length is t s1 =880 hours degradation curve of each sample is recorded as S1; after time t2=301 in G2, the time length is t s2 = 800 hours degradation curve of each sample is recorded as S2.

[0086] Step 34: Perform the Mann-Whitney U test on the degradation data of the S1 and C1 groups at the same time, and perform the Mann-Whitney U test on the degradation data of the S2 and C2 groups at the same time, and obtain two p-value curves. The part of the curve with p < 0.05 corresponds to the distribution of the two groups of samples with significant differences. Figure 4 As shown in the figure, the Mann-Whitney U test results for the degradation paths of groups S1 and C1 are less than 0.05 after approximately 580 hours, indicating that there is a significant difference in the degradation paths, which means that a temperature interaction exists. Compared with the accelerated degradation test group (S1) that was maintained at 120°C, the temperature interaction was introduced by first applying 25°C and then 120°C (C1). This effect affects the degradation, resulting in differences in degradation rates at the same temperature of 120°C, starting from the average degradation amount of the same sample. Figure 5 As shown in the figure, the degradation paths for groups S2 and C2 show a Mann-Whitney U test result of less than 0.05 after approximately 380 hours, indicating a significant difference between the degradation paths. This suggests the presence of a temperature interaction. Compared to the accelerated degradation test group (S2), which was maintained at 25°C, the temperature interaction introduced by first applying 120°C and then 25°C affects degradation, resulting in differences in degradation rates at the same 25°C temperature, starting from the same average degradation value.

[0087] The above examples are merely illustrative of the calculation model and process of the present invention and are not intended to limit the embodiments of the present invention. Persons skilled in the art will readily appreciate that other variations or modifications based on the above description are possible. This list of embodiments is not exhaustive; however, any obvious variations or modifications derived from the technical solution of the present invention remain within the scope of protection of the present invention.

Claims

1. A method for identifying temperature interaction of threshold voltage degradation of silicon carbide power MOSFET, characterized in that: include: Step 1: Conduct accelerated degradation tests on SiC power MOSFETs to obtain threshold voltage degradation data for temperature interaction identification. The specific process includes the following steps: Step 11: Determine the MOSFET's turn-on signal voltage, turn-off signal voltage, and signal frequency based on the actual drive signal parameters of the MOSFET in the circuit; and determine the accelerated degradation test temperature range; Step 12: Set n groups of constant temperature accelerated degradation tests; set the voltage and frequency of the MOSFET on / off signals in each group to be the same according to step 11; in the test, the drain and source of the MOSFET are short-circuited, and the drive signal is applied only to the gate; select n temperatures within the accelerated degradation test temperature range, and record them as T1 to T2. n ; Step 13: Design the duration and frequency of the constant temperature accelerated degradation test and conduct the test; Step 14: At T1 to T n Select two temperatures T i With T j ; Step 15: Set up two groups of two-stage temperature accelerated degradation tests; in the two-stage temperature accelerated degradation test group 1, first apply T i , then apply T j ; In the two-stage temperature accelerated degradation test group 2, T j , then apply T i ;Other test settings are the same as S12; Step 16: Design the duration and test frequency of the two-stage temperature accelerated degradation test, and conduct the two-stage temperature accelerated degradation test; Step 2: Process the threshold voltage degradation data obtained in step 1 by fitting and smoothing methods; The temperature in the constant temperature accelerated degradation test is T i With T j The sample data of each group and the sample data of each group in the second stage of the two-stage temperature accelerated degradation test are fitted respectively: V th (t)=a1·exp(a2·t)+a3·exp(a4·t) (1) Among them, V th (t) is the value of the threshold voltage at time t, a1, a2, a3, and a4 are parameters that need to be determined by fitting; Step 3: Perform statistical tests on the processed degradation path data and determine whether the degradation is affected by temperature interaction based on the statistical test results.

2. The method for identifying temperature interaction of threshold voltage degradation of silicon carbide power MOSFET according to claim 1, characterized in that: In step 1, the accelerated degradation test temperature range needs to be determined. In this process, the temperature operating range specified in the MOSFET parameter manual is determined as the accelerated degradation test temperature range.

3. The method for identifying temperature interaction of threshold voltage degradation of silicon carbide power MOSFET according to claim 1, characterized in that: The test duration designed in step 13 should ensure that the mean threshold voltage of the test samples in each group can degrade by more than 10% of the initial mean value.

4. The method for identifying temperature interaction of threshold voltage degradation of silicon carbide power MOSFET according to claim 3, characterized in that: The test frequency designed in step 13 should ensure that the number of tests for each group during the test period is greater than 10.

5. The method for identifying temperature interaction of threshold voltage degradation of silicon carbide power MOSFET according to claim 1, characterized in that: The process of designing the duration and test frequency of the two-stage temperature accelerated degradation test and conducting the two-stage temperature accelerated degradation test in step 16 includes the following steps: In the two-stage temperature accelerated degradation test group 1, T i , when the threshold voltage mean of the test sample degrades by P% of the initial mean, the application duration is t s1 T j ; In the two-stage temperature accelerated degradation test group 2, T j , when the threshold voltage mean of the test sample degrades by P% of the initial mean, the application duration is t s2 T j .

6. The method for identifying temperature interaction of threshold voltage degradation of silicon carbide power MOSFET according to claim 5, characterized in that: The P% is set to 5%.

7. The method for identifying temperature interaction of threshold voltage degradation of silicon carbide power MOSFET according to claim 5, characterized in that: The application time of the second stage temperature of the two-stage temperature accelerated degradation test group 1 and the two-stage temperature accelerated degradation test group 2 should ensure that at least 10 test points can be obtained in each group.

8. A method for identifying temperature interaction of threshold voltage degradation of a silicon carbide power MOSFET according to any one of claims 1 to 7, characterized in that: The specific process of step 3 includes the following steps: Step 31: Calculate the average threshold voltage degradation V of the test samples in Group 1 and Group 2 at the end of the first stage of the two-stage temperature accelerated degradation test. th1 and V th2； Step 32: Determine the average degradation of samples in G1 as V th1 The time is recorded as t1, and the average degradation of samples in G2 is determined to be V th2 The time is recorded as t2; Step 33: After time t1 in G1, the time length is t s1 The degradation curve of each sample is recorded as S1; after time t2 in G2, the time length is t s2 The degradation curve of each sample is recorded as S2; Among them, G1 is the temperature T in the constant temperature accelerated degradation test in step 2. j The degradation curves of each sample obtained by the group are shown in Figure 2. G2 is the temperature T in the constant temperature accelerated degradation test fitted in step 2. i The degradation curves of each sample obtained by the group; Step 34: Perform a Mann-Whitney U test on the degradation data of groups S1 and C1 at the same time, and perform a Mann-Whitney U test on the degradation data of groups S2 and C2 at the same time, to obtain two p-value curves. Determine the distribution difference of the corresponding two groups of samples based on the p in the curves, and then determine the temperature level interaction; Wherein, C1 is the degradation curve of each sample obtained by fitting the two-stage temperature accelerated degradation test group 1 in step 2, and C2 is the degradation curve of each sample obtained by fitting the two-stage temperature accelerated degradation test group 2 in step 2.

9. The method for identifying temperature interaction of threshold voltage degradation of silicon carbide power MOSFET according to claim 8, characterized in that: According to the p in the curve, the distribution difference of the two groups of samples is determined, and in the process of determining the interaction of temperature levels, the distribution difference of the two groups of samples corresponding to the part of the curve where p < the discrimination threshold exists, that is, there is a temperature level interaction.

10. The method for identifying temperature interaction of threshold voltage degradation of silicon carbide power MOSFET according to claim 9, characterized in that: The discrimination threshold is 0.05.

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