Defect detection method and device for 4H-SiC device
A non-destructive method for detecting defects in 4H-SiC devices using controlled current input and optical spectroscopy effectively addresses the inefficiencies of existing techniques, enabling real-time monitoring and accurate defect identification.
Patent Information
- Application Number
- CN202510483458.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-17
- Publication Date
- 2025-07-15
AI Technical Summary
Existing methods for detecting defects in 4H-SiC power devices are inefficient and often require destructive analysis, making it difficult to assess double-bias degradation and impacting the reliability of silicon carbide metal oxide semiconductor field effect transistors (SiC MOSFETs).
A non-destructive method involving controlled input of detection current based on device type, temperature, and frequency, followed by optical spectroscopy and dynamic time planning to analyze peak values and normalize spectra for defect identification.
Enables real-time monitoring of defect expansion and accurate identification of defect types in 4H-SiC devices, improving efficiency and reducing the risk of device damage.
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Figure CN120314740A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of semiconductor detection, and particularly relates to a method and device for defect detection of 4H-SiC devices. Background Art
[0002] The reliability of 4H-SiC-based power devices is jointly affected by the device itself and the package. When such devices are used as converters, they have the characteristic of relatively high intrinsic defects, which is a major challenge hindering the development of high-power silicon carbide metal oxide semiconductor field effect transistor (SiC MOSFET) devices at present. Intrinsic material defects will cause bipolar degradation in the bipolar conduction state of the device, mainly because the Shockley stacking fault (SSF) in the hexagonal silicon carbide structure lattice forms an embedded 3C-SiC region in the 4H-SiC structure. This degradation has a permanent impact on the electrical performance of the device, increasing the power system loss and the failure risk. At present, bipolar degradation is mainly initially determined by the change of the electrical parameters of the device. The final qualitative analysis often requires destructive treatment of the device and uses methods such as potassium hydroxide (KOH) etching or photoluminescence for characterization. Such detection makes the judgment difficult, and the damage to the device cannot be recovered. In actual experiments, there are many difficulties in monitoring bipolar degradation. Summary of the Invention
[0003] An object of the present invention is to provide a method and device for defect detection of 4H-SiC devices, which can solve the above technical problems in the prior art.
[0004] According to the first aspect of the present invention, a method for defect detection of 4H-SiC devices is provided, and the method includes:
[0005] Determine the type of detection current, the maximum value of the detection current, and the current density according to the type of the device to be detected, the maximum temperature of the device to be detected, the ambient temperature, and the number of cycles during the detection process;
[0006] Input the detection current to the device to be detected according to the type, maximum value, and current density of the detection current;
[0007] Perform spectral detection on the device to be detected at a preset frequency, and collect spectral data at multiple different temperatures;
[0008] Process the spectral data at multiple different temperatures by a dynamic time warping method to obtain the relationship between temperature and dynamic distance values;
[0009] Normalize the peak curves at different temperatures according to the relationship between temperature and dynamic distance values;
[0010] Determine the defect type of the device to be detected according to the normalized peak result.
[0011] Optionally, determining the type of the detection current, the maximum value of the detection current, and the current density according to the type of the device to be detected, the maximum temperature of the device to be detected, and the ambient temperature includes:
[0012] Determine the junction temperature difference of the device to be detected according to the type of the device to be detected;
[0013] Determine whether the type of the device to be detected, the junction temperature difference of the device to be detected, and the number of cycles meet the preset conditions, where the preset conditions include: the type of the device to be detected is a traditional bonding package device, the junction temperature difference of the device to be detected is less than 150 °C, and the number of cycles is less than 3000 times;
[0014] If it is satisfied, determine that the type of the detection current to be detected is a pulsed current;
[0015] If it is not satisfied, determine that the type of the detection current to be detected is a direct current;
[0016] Determine the maximum value of the detection current and the current density according to the type of the detection current.
[0017] Optionally, when the type of the detection current is a direct current, the calculation formula for the maximum value of the detection current is as follows:
[0018]
[0019] where, I BD1 is the maximum value when the detection current is a direct current, T1 is the maximum temperature of the device to be detected, T2 is the ambient temperature, R th is the thermal resistance, R on1 is the resistance value of the body diode of the device to be detected at temperature T1 and current I BD1 state;
[0020] The calculation formula for the current density is as follows:
[0021]
[0022] where, D current1 is the current density when the detection current is a direct current, A active is the active area.
[0023] Optionally, when the type of the detection current is a pulsed current, the calculation formula for the maximum value of the detection current is as follows:
[0024]
[0025] where, I BD2To detect the maximum value when the detected current is a pulsed current, T1 is the maximum temperature of the device to be detected, T2 is the ambient temperature, and R th is the thermal resistance, and R on2 is the resistance value of the body diode of the device to be detected at temperature T1 and current I BD2 condition;
[0026] The calculation formula for current density is as follows:
[0027]
[0028] where D current2 is the current density when the detected current is a pulse, and A active is the active area.
[0029] Optionally, processing the spectral data at the multiple different temperatures by the dynamic time warping method to obtain the relationship between temperature and dynamic distance value includes:
[0030] Performing deconvolution on the spectral data at each temperature to obtain two peak data corresponding to each temperature;
[0031] Using the dynamic time warping method to calculate the dynamic distance value between two adjacent temperatures;
[0032] Determining the relationship between temperature and dynamic distance value according to all the dynamic distance data.
[0033] Optionally, the two peak data include:
[0034] The wavelength of 400 nm - 500 nm is the first peak, and the wavelength of 450 nm - 550 nm is the second peak.
[0035] Optionally, the relationship between the temperature and the dynamic distance value is expressed as:
[0036] T vj = log a (b·d p + c);
[0037] where T vj is the junction temperature obtained by indirect measurement, dp is the dynamic distance value, and a, b, and c are coefficients.
[0038] Optionally, the normalization of the peak curves at different temperatures is expressed as:
[0039]
[0040] where I norm represents the normalization result, I EL is the bipolar emission current, μ is the mean value, σ is the standard deviation, and Trt is the room temperature of the test environment, T vj is the junction temperature obtained by indirect measurement.
[0041] Optionally, determining the defect type of the device to be detected according to the normalized peak result includes:
[0042] According to the normalized peak result, by analyzing the peak value of the wave peak, the wave peak offset, and the newly generated peak, query the pre-configured relationship table between the 4H-SiC bulk material defects and the emission wave peak to determine the defect type of the device to be detected.
[0043] According to the second aspect of the present invention, there is provided a detection device applying the defect detection method of a 4H-SiC device according to the first aspect of the present invention, including:
[0044] A device to be detected, the device to be detected is a SiC MOSFET device with a Kelvin source at four ports, the drain of the device to be detected is grounded, the source of the device to be detected is connected to a positive potential, the Kelvin source of the device to be detected and the source of the device to be detected are connected at the same potential, and the gate of the device to be detected is connected to zero or a negative potential;
[0045] An optical fiber probe, one end of the optical fiber probe is fixed on the side of the device to be detected, the other end of the optical fiber probe is connected to a spectrometer, and the optical fiber probe is used to detect the light emitted during the power-on test of the device to be detected.
[0046] The beneficial effects of the present invention are as follows: (1) It can realize the real-time monitoring of the dislocation defect expansion during the bipolar degradation process of 4H-SiC devices; (2) It can identify the types of defects generated, analyze the influence magnitude of the defects on the device performance, and realize the auxiliary screening of abnormal devices; (3) Compared with the multi-parameter electrical characterization and failure analysis after experiments, it has higher efficiency and accuracy and will not affect the device. Description of the Drawings
[0047] Figure 1 is a flowchart of a defect detection method for a 4H-SiC device in an embodiment of the present invention.
[0048] Figure 2 is a schematic diagram of a defect detection device for a 4H-SiC device in an embodiment of the present invention. Detailed Embodiments
[0049] Now, various exemplary embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that: Unless otherwise specifically stated, the relative arrangements, numerical expressions, and numerical values of the components and steps set forth in these embodiments do not limit the scope of the present invention.
[0050] The following description of at least one exemplary embodiment is merely illustrative and in no way restrictive of the invention, its application, or its use.
[0051] Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such technologies, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values should be construed as merely exemplary and not as limitations. Thus, other examples of exemplary embodiments may have different values.
[0052] It should be noted that like reference numerals and letters denote like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.
[0053] In the description and claims of the present invention, features related to the terms "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more. In addition, "and / or" in the specification and claims means at least one of the connected objects, and the character " / " generally means an "or" relationship between the associated objects before and after.
[0054] With the rapid development of the power electronics market, SiC has become an ideal material for high-power semiconductor devices in electric vehicles, aerospace, and high-power conversion systems. This is because it has superior characteristics such as a wide bandgap (about 3.26 eV for 4H-SiC at room temperature), a high critical breakdown field, low switching power loss, and high operating temperature. With the continuous progress of SiC technology, currently 3.3 kV devices have also been gradually commercialized. Such high-voltage devices have a thicker epitaxial layer and theoretically have a higher defect density, resulting in more obvious phenomena during the testing process mentioned in the present invention.
[0055] However, SiC power MOSFETs still have serious problems, such as unstable threshold voltage caused by gate oxide interface states, robustness against avalanche short-circuit surges, bulk material defects (extended defects and point defects), etc. These problems may reduce the performance and reliability of SiC power devices. During the conduction process of the SiC MOSFET body diode, there is a bipolar current. In the state of large injection of minority carriers, carrier recombination occurs in the epitaxial layer, which will cause the expansion of SSFs in the epitaxial layer, resulting in the performance degradation of the device, namely "bipolar degradation".
[0056] It has been proven that during the forward bias operation of the body diode, that is, during the conduction of the PiN junction, a single Shockley-type stacking fault, also known as a recombination-induced stacking fault (RISF), will expand from the basal plane dislocation (BPD) into the grown epitaxial layer. However, this phenomenon occurs in SiC power MOSFETs when the forward body diode conducts. The body diode is very important because it acts as a "freewheeling diode" in many practical power conversion applications. The extended SSFs will cause an increase in the forward voltage drop, on-resistance, and drain leakage current of the body diode of the SiC MOSFET. RISFs provide sufficient energy for some dislocations (PDs) (dislocations at the boundary of RISFs) to overlap and propagate along the overlap. During the period when the SSF expands from the BPD, some dislocations are fixed carbon-core partial dislocations and mobile silicon-core partial dislocations. Since RISF is radiative recombination, its process can be detected by hyperspectral electroluminescence imaging.
[0057] Existing detection methods are relatively complete in characterizing the defects of bulk materials and are usually used during the substrate and epitaxial manufacturing processes. However, for fabricated devices, currently, except for electrical parameter testing and destructive failure analysis, there is no good method for bipolar degradation detection. Especially for SiC MOSFET devices, parameters such as source-drain current, on-resistance, and forward voltage drop of the body diode are severely affected by the degradation of the threshold voltage. And in the bipolar degradation experiment, due to the enhanced hole injection, the threshold voltage inevitably drops, which leads to the degradation of electrical parameters being affected by multiple parameters, making it difficult to determine bipolar degradation. Qualitative analysis of epitaxial degradation often requires destructive treatment of the device, such as using KOH etching or performing photoluminescence on the device with the package removed for characterization. Various dislocations and defects that appear on the epitaxial layer or substrate can be obtained. Such detection makes it difficult to determine in reliability tests or early aging screening of commercial devices, and the damage to the device cannot be recovered. In addition, during the bipolar degradation process, the device is in a state of self-heating due to the current flowing through the body diode, and the device will continuously remain at a high temperature, not only causing parameter drift. In addition, photons generated by direct recombination transitions in the body diode and those released by deep-level recombination will produce two spectral peaks. At high temperatures, the bandgap narrows, direct recombination is enhanced, the intensity of the first peak increases, deep-level defects are released, causing the peak value of the second peak to decrease. And both peaks will shift, which hinders the analysis of bipolar degradation using spectral results.
[0058] As Figure 1 shown, this embodiment introduces a defect detection method for a 4H-SiC device, and the method includes steps 1100 - 1600.
[0059] Step 1100: Determine the type of the detection current, the maximum value of the detection current, and the current density according to the type of the device to be detected, the maximum temperature of the device to be detected, and the ambient temperature.
[0060] To achieve bipolar degradation, it is necessary to increase the current density as much as possible, but the device junction temperature needs to be maintained within a controllable range, usually 175°C. The types of the detection current include direct current and pulse, and the type of the detection current can be determined according to the type of the device to be detected. The ambient temperature also affects the electroluminescence effect of the device to be detected, and the detection current needs to be adjusted according to the ambient temperature.
[0061] Step 1200: Input a detection current to the device to be detected according to the type, maximum value, and current density of the detection current.
[0062] Step 1300: Perform spectral detection on the device to be detected at a preset frequency, and collect spectral data at multiple different temperatures.
[0063] After determining the current conditions, the device will continue to age in this state. Depending on the specific defect situation, bipolar degradation may last for 10 - 60 minutes, and it is ensured that spectral detection is performed every 10 minutes.
[0064] Step 1400: Process the spectral data at the multiple different temperatures by using the dynamic time warping method to obtain the relationship between the temperature and the dynamic distance value.
[0065] The dynamic distance value reflects the change of the spectral data with temperature.
[0066] Step 1500: Normalize the peak curves at different temperatures according to the relationship between the temperature and the dynamic distance value.
[0067] Specifically, the normalization of the peak curves at different temperatures is expressed as:
[0068]
[0069] where, I norm represents the normalization result, I EL is the bipolar luminescence current, μ is the mean value, σ is the standard deviation, T rt is the room temperature of the test environment, and T vj is the junction temperature obtained by indirect measurement.
[0070] Step 1600: Determine the defect type of the device to be detected according to the normalized peak result.
[0071] Specifically, based on the normalized peak results, by analyzing the peak-to-peak value, peak shift, and newly generated peaks, and referring to the relationship table between 4H-SiC bulk material defects and emission peaks, the defect type of the device to be detected can be obtained. The relationship table between 4H-SiC bulk material defects and emission peaks can be obtained based on the emission wavelengths of different types of defects statistically analyzed in existing related research. This relationship table records the corresponding relationships between multiple peaks and defect types.
[0072] In this embodiment, step 1100 includes steps 1110 - 1150.
[0073] Step 1110: Determine the junction temperature difference of the device to be detected according to the type of the device to be detected.
[0074] Step 1120: Determine whether the type of the device to be detected, the junction temperature difference of the device to be detected, and the number of cycles meet the preset conditions, where the preset conditions include: the type of the device to be detected is a traditional bonded package device, the junction temperature difference of the device to be detected is less than 150°C, and the number of cycles is less than 3000 times.
[0075] Step 1130: If satisfied, determine that the type of the current to be detected is a pulsed current.
[0076] Step 1140: If not satisfied, determine that the type of the current to be detected is a direct current.
[0077] Step 1150: Determine the maximum value and current density of the detection current according to the type of the detection current.
[0078] Specifically, when the type of the detection current is a direct current, the calculation formula for the maximum value of the detection current is as follows:
[0079]
[0080] where I BD1 is the maximum value when the detection current is a direct current, T1 is the maximum temperature of the device to be detected, T2 is the ambient temperature, R th is the thermal resistance, and R on1 is the resistance value of the body diode of the device to be detected at temperature T1 and current I BD1 condition.
[0081] Step 1130: The calculation formula for the current density is as follows:
[0082]
[0083] where D current1 is the current density, and A active is the active area.
[0084] When the current to be detected is direct current, the current density needs to reach 140 - 240 A / cm 3 。
[0085] Specifically, when the type of the detected current is pulsed current, the calculation formula for the maximum value of the detected current is as follows:
[0086]
[0087] where I BD2 is the maximum value when the detected current is pulsed current, T1 is the maximum temperature of the device to be detected, T2 is the ambient temperature, and R th is the thermal resistance, and R on2 is the resistance value of the body diode of the device to be detected at temperature T1 and current I BD2 condition.
[0088] Step 1160: The calculation formula for the current density is as follows:
[0089]
[0090] where D current2 is the current density when the detected current is pulsed, and A active is the active area.
[0091] When the detected current is pulsed current, the current density can reach 240 - 500 A / cm 3 。The duty cycle of the pulsed current can be 10%, specifically subject to the actual on - machine experimental environment and working conditions.
[0092] For exciting bipolar degradation, using pulsed current is better, but pulsed current will cause large fluctuations in the device junction temperature. If the test time is too long, it will introduce degradation at the package level, increasing the difficulty of result analysis on the one hand and damaging the device on the other hand. In the DC mode, long - term testing will not introduce package degradation. However, in the DC mode, higher requirements are placed on the heat dissipation ability, and it is difficult to maintain a high current density. Using a pulsed current with a low duty cycle can achieve a higher density.
[0093] The present invention selects different test currents for different devices by judging whether the preset conditions are met. On the one hand, it can protect the device and avoid package degradation during the detection process. On the other hand, it can improve the current density as much as possible.
[0094] In this embodiment, step 1400 includes steps 1410 - 1430.
[0095] Step 1410: Perform deconvolution on the spectral data at each temperature to obtain two peak data corresponding to each temperature.
[0096] Step 1420: Use the dynamic time warping method to calculate the dynamic distance value between two adjacent temperatures.
[0097] Step 1430: Determine the relationship between temperature and dynamic distance value based on all the dynamic distance data.
[0098] Specifically, the two peak data include: the first peak is at a wavelength of 400 nm - 500 nm, and the second peak is at a wavelength of 450 nm - 550 nm.
[0099] First, obtain the spectral result of the device at a certain temperature state, perform deconvolution on it to obtain two peak data. Take 400 nm - 500 nm as the first peak and 450 nm - 550 nm as the second peak. Then change the temperature, for example, increase it by 25 °C to 50 °C, and repeat the above method of obtaining peaks again to obtain two peak data at another temperature.
[0100] Then, use the dynamic time warping method to calculate the dynamic distance value between a temperature of 25 °C and a temperature of 50 °C, denoted as dp 25 . And so on, by increasing the temperature in a certain step, obtain the relationship between temperature and dynamic distance value.
[0101] Specifically, the relationship between temperature and dynamic distance value is expressed as:
[0102] T vj = log a (b·d p + c);
[0103] Where, T vj is the junction temperature obtained by indirect measurement, dp is the dynamic distance value, and a, b, c are coefficients.
[0104] The junction temperature of the device to be detected can be measured by methods such as the case temperature thermal resistance calculation method and the thermal sensitive parameter calculation method.
[0105] Specifically, the state transition equation of the dynamic time warping method is as follows:
[0106] dp(i,j) = min(dp(i - 1,j - 1),dp(i - 1,j),dp(i,j - 1)) + d(i,j);
[0107] Where, dp(i,j) is the data point in the spectral result, and d(i,j) is the cost.
[0108] As Figure 2 shown, this embodiment introduces a defect detection device for 4H - SiC devices. This device applies a defect detection method for 4H - SiC devices according to any embodiment of the present invention. This device includes:
[0109] Device to be detected, where the device to be detected is a SiC MOSFET device with a four-port and a Kelvin source. The drain of the device to be detected is grounded, the source of the device to be detected is connected to a positive potential, the Kelvin source of the device to be detected and the source of the device to be detected are connected at the same potential, and the gate of the device to be detected is connected to zero or a negative potential;
[0110] Optical fiber probe, one end of the optical fiber probe is fixed to the side of the device to be detected, the other end of the optical fiber probe is connected to a spectrometer, and the optical fiber probe is used to detect the light emitted during the power-on test of the device to be detected.
[0111] Although some specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are only for illustration and not for limiting the scope of the present invention. Those skilled in the art should understand that the above embodiments can be modified without departing from the scope and spirit of the present invention. The scope of the present invention is defined by the appended claims.
[0112] Those of ordinary skill in the art can realize that the modules and algorithm steps described in combination with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. Professionals can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the present invention.
[0113] Those skilled in the art can clearly understand that for the convenience and conciseness of description, the specific working processes of the above-described devices and equipment can refer to the corresponding processes in the foregoing method embodiments and will not be elaborated herein.
[0114] In the embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only illustrative. For example, the division of the modules is only a logical function division, and there can be other division methods in actual implementation. For example, multiple modules or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed couplings or direct couplings or communication connections to each other can be through some interfaces, and the indirect couplings or communication connections of the devices or modules can be in electrical, mechanical or other forms.
[0115] The module described as a separation component may or may not be physically separated. The component shown as a module may or may not be a physical module, that is, it may be located in one place or distributed across multiple network modules. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of the embodiment of the present invention.
[0116] In addition, each functional module in the embodiment of the present invention can be integrated into a processing module, or each module can exist physically alone, or two or more modules can be integrated into one module.
[0117] If the above functions are implemented in the form of software functional modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on such understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods of the various embodiments of the present invention. The aforementioned storage medium includes: various media such as USB flash drives, mobile hard disks, ROM, RAM, magnetic disks, or optical discs that can store program codes.
[0118] The above description is only a preferred embodiment of the present application and an explanation of the applied technical principles. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by the specific combination of the above technical features, and should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the technical solutions formed by mutually replacing the above features with the (but not limited to) technical features having similar functions disclosed in the present application.
[0119] It should be understood that the magnitudes of the sequence numbers of the steps in the content of the present invention and the embodiments do not absolutely mean the sequence of execution. The execution sequence of each process should be determined according to its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of the present invention. For the purpose of illustration and description, the foregoing description of the implementation of the present disclosure has been given. The foregoing description is not exhaustive and is not intended to limit the present disclosure to the exact form disclosed. According to the above teachings, various modifications and variations are possible, or various modifications and variations may be obtained from the practice of the present disclosure. These embodiments are selected and described to illustrate the principles of the present disclosure and its practical applications, so that those skilled in the art can utilize the present disclosure in various embodiments and various modifications suitable for the specific purposes contemplated.
Claims
1. A method for defect detection of a 4H-SiC device, characterized in that, The method includes: Determining the type of the detection current, the maximum value of the detection current, and the current density according to the type of the device to be detected, the maximum temperature of the device to be detected, the ambient temperature, and the number of cycles during the detection process; Inputting the detection current to the device to be detected according to the type, the maximum value, and the current density of the detection current; Performing spectral detection on the device to be detected at a preset frequency, and collecting spectral data at multiple different temperatures; Processing the spectral data at the multiple different temperatures by a dynamic time warping method to obtain the relationship between the temperature and the dynamic distance value; Normalizing the peak curves at different temperatures according to the relationship between the temperature and the dynamic distance value; Determining the defect type of the device to be detected according to the normalized peak result.
2. The method according to claim 1, wherein The determining the type of the detection current, the maximum value of the detection current, and the current density according to the type of the device to be detected, the maximum temperature of the device to be detected, and the ambient temperature includes: Determining the junction temperature difference of the device to be detected according to the type of the device to be detected; Determining whether the type of the device to be detected, the junction temperature difference of the device to be detected, and the number of cycles meet preset conditions, where the preset conditions include: the type of the device to be detected is a traditional bonding package device, the junction temperature difference of the device to be detected is less than 150 °C, and the number of cycles is less than 3000 times; If satisfied, determining that the type of the detection current to be detected is a pulsed current; If not satisfied, determining that the type of the detection current to be detected is a direct current; Determining the maximum value of the detection current and the current density according to the type of the detection current.
3. The method according to claim 2, wherein When the type of the detection current is a direct current, the calculation formula for the maximum value of the detection current is as follows: Wherein, I BD1 is the maximum value when the detected current is a direct current, T1 is the maximum temperature of the device to be detected, T2 is the ambient temperature, R th is the thermal resistance, R on1 is the resistance value of the body diode of the device to be detected at temperature T1 and current I BD1 under the state; The calculation formula for the current density is as follows: Among them, D current1 is the current density when the detected current is direct current, A active is the area of the active region.
4. The method according to claim 2, characterized in that, When the type of the detection current is a pulsed current, the calculation formula for the maximum value of the detection current is as follows: Among them, I BD2 is the maximum value when the detected current is a pulsed current, T1 is the maximum temperature of the device to be detected, T2 is the ambient temperature, and R th is the thermal resistance, and R on2 is the resistance value of the body diode of the device to be detected at temperature T1 and current I BD2 under the state; The calculation formula for the current density is as follows: Among them, D current2 is the current density when the detected current is a pulse, in A active is the area of the active region.
5. The method according to claim 1, characterized in that The processing the spectral data at the multiple different temperatures by a dynamic time warping method to obtain the relationship between the temperature and the dynamic distance value includes: Performing deconvolution on the spectral data at each temperature to obtain two peak data corresponding to each temperature; Using the dynamic time warping method to calculate the dynamic distance value between two adjacent temperatures; Determining the relationship between the temperature and the dynamic distance value according to all the dynamic distance data.
6. The method according to claim 5, wherein The two peak data include: The wavelength of 400 nm - 500 nm is the first peak, and the wavelength of 450 nm - 550 nm is the second peak.
7. The method according to claim 5, wherein The relationship between the temperature and the dynamic distance value is expressed as: T vj = log a (b·d p + c); Among them, T vj is the junction temperature obtained by indirect measurement, dp is the dynamic distance value, and a, b, and c are coefficients.
8. The method according to claim 7, characterized in that, The normalizing the peak curves at different temperatures is expressed as: Among them, I norm represents the normalization result, I EL is the bipolar luminescence current, μ is the mean value, σ is the standard deviation, T rt is the room temperature of the test environment, T vj is the junction temperature obtained by indirect measurement.
9. The method according to claim 1, wherein The determining the defect type of the device to be detected according to the normalized peak result includes: According to the normalized peak result, by analyzing the peak value of the wave peak, the peak shift, and the newly generated peak, querying the pre-configured relationship table between the 4H-SiC bulk material defects and the emission wave peak to determine the defect type of the device to be detected.
10. A detection device applying the defect detection method of a 4H-SiC device according to any one of claims 1-9, characterized in that, Includes: Device to be detected, the device to be detected is a SiC MOSFET device with a four-port and a Kelvin source electrode, the drain of the device to be detected is grounded, the source electrode of the device to be detected is connected to a positive potential, the Kelvin source electrode of the device to be detected is connected to the source electrode of the device to be detected at the same potential, and the gate electrode of the device to be detected is connected to zero or a negative potential; Optical fiber probe, one end of the optical fiber probe is fixed on the side of the device to be detected, the other end of the optical fiber probe is connected to a spectrometer, and the optical fiber probe is used to detect the light emitted during the power-on test of the device to be detected.