Bipolar degradation screening test device and method for multi-device series mixed detection

Abstract

The invention discloses a bipolar degradation screening test device and method for multi-device series mixed detection. The bipolar degradation screening test device comprises an upper computer, a temperature detection unit, a cooling unit and a detection circuit. Wherein the cold end of the cooling unit is provided with a test platform, the test platform is provided with a detection circuit, and the measuring end of the temperature detection unit is installed on the test platform. A plurality of devices to be detected are connected in series in the detection circuit, and the detection circuit is provided with a current on-off switch. According to the device-level bipolar degradation test screening method for multi-device series mixed detection, test current is continuously conducted in a detection circuit on the basis of a device by driving a tested device under temperature control and temperature measurement conditions, and data is collected online in the test process; the method is used for screening and evaluating the bipolar degradation reliability of the silicon carbide device under the specified current stress condition, and the screening efficiency and accuracy of the bipolar degradation test of the silicon carbide device can be improved.

Description

Technical Field

[0001] This invention belongs to the field of microelectronics technology, specifically relating to a bipolar degradation screening test device for multi-device tandem mixed testing. Background Technology

[0002] With the continuous development of power electronics technology, more and more fields, such as new energy vehicles, charging piles, smart grids, photovoltaic inverters and wind power generation, urgently need electronic devices that can work in extreme environments such as high temperature and high frequency.

[0003] Silicon carbide (SiC) devices offer numerous advantages over traditional silicon (Si) devices, including higher switching frequencies, lower operating temperatures, higher current and voltage capacities, and lower losses, leading to higher power density, reliability, and efficiency. Consequently, SiC devices, primarily represented by SiC diodes and silicon carbide metal-oxide-semiconductor field-effect transistors (SiC MOSFETs), are widely used. SiC diodes offer advantages such as fast switching speeds, high voltage withstand capability, low reverse leakage current, and low switching capacitance. Furthermore, their reverse recovery time is shorter than that of Si-based diodes, typically ranging from a few nanoseconds to tens of nanoseconds, improving system efficiency and reducing energy waste. They are suitable for high-frequency and high-temperature applications, such as power supplies and radio frequency circuits. SiC MOSFETs feature high blocking voltage, high operating frequencies, strong high-temperature resistance, low on-state resistance, and low switching losses, making them widely used in high-frequency, high-voltage power systems.

[0004] Furthermore, when conventional SiC devices operate in bipolar mode, due to crystal defects, when the shear stress component of external stress reaches a certain critical value, the crystal slips on the slip system, causing macroscopic deformation and resulting in dislocation defects. The energy generated by electron-hole recombination causes stacking faults to expand and grow at the dislocation sites on the substrate surface. Stacking faults reduce carrier lifetime and weaken the conductance modulation effect, thus causing changes in characteristic parameters such as body diode voltage drop, forward conduction resistance, and IV characteristic curve, i.e., bipolar degradation of the SiC device. These stacking faults will propagate to the chip surface and then stop propagating. The area covered by the expanded stacking faults can no longer conduct electricity, reducing the effective active area of ​​the chip and severely affecting the device's reliability. Therefore, whether a SiC device will undergo bipolar degradation under specified current stress conditions is an important means of evaluating the reliability of such devices in practical applications.

[0005] To address the aforementioned issues, existing technologies include corresponding detection and screening circuits, devices, and equipment for pre-detection and screening of silicon carbide devices. For example, application CN118130995A discloses a bipolar degradation test circuit and a bipolar degradation test method, comprising: a test circuit, a first driving circuit, a second driving circuit, and a monitoring circuit. The test circuit includes an auxiliary resistor and at least one SiC MOSFET under test. The first driving circuit provides a first pulse electrical signal to each SiC MOSFET under test when they are in the off state, thereby controlling the application of current stress to each SiC MOSFET. The second driving circuit provides a second pulse electrical signal to each SiC MOSFET under test when they are in the on state. The monitoring circuit acquires a first degradation parameter of each SiC MOSFET under test under the first pulse electrical signal and a second degradation parameter of each SiC MOSFET under test under the second pulse electrical signal. The above technical solution can monitor the degradation parameters of multiple SiC MOSFET devices simultaneously, and can perform corresponding tests and screening. However, its application type is effective, but it does not take into account the influence of actual operating temperature, i.e. junction temperature.

[0006] In summary, further improvements are needed to the testing and screening devices and methods applicable to bipolar degradation of SiC devices, in order to provide a universal and rapid detection technology that can screen and evaluate the bipolar degradation reliability of SiC devices under specified stress conditions by collecting experimental data. Summary of the Invention

[0007] This invention provides a bipolar degradation screening test apparatus and method for multi-device tandem mixed testing to solve the above-mentioned problems.

[0008] The present invention adopts the following technical solution:

[0009] On one hand, the present invention provides a bipolar degradation screening test device for multi-device series mixed testing, which includes a host computer, a temperature detection unit, a cooling unit and at least one set of detection circuits; the host computer is electrically connected to the temperature detection unit, the cooling unit and the detection circuits respectively;

[0010] The cold end of the cooling unit is provided with a test platform, the test platform is equipped with the detection circuit, and the measuring end of the temperature detection unit is installed on the test platform.

[0011] A single detection circuit contains multiple silicon carbide devices to be tested connected in series, and the detection circuit is equipped with a current on / off switch.

[0012] Optionally, the current switching switch includes a main switch;

[0013] A current source, a galvanometer, and the main switch are connected in series on the main circuit of the detection circuit.

[0014] A voltmeter is also installed on the main circuit of the detection circuit.

[0015] Optionally, the current switching switch includes a bypass switch;

[0016] Each detection position in the detection circuit is equipped with a silicon carbide device and has a bypass, with a constant current source and the bypass switch connected in series on the bypass.

[0017] Optionally, the voltmeter may be connected across all the detection bits of the detection circuit.

[0018] Optionally, the current switching switch is a pulse modulation switch.

[0019] Optionally, the cooling unit is an air-cooled or water-cooled device;

[0020] The cold end of the cooling unit directly or indirectly contacts the housing of the silicon carbide device.

[0021] Optionally, the controller of the cooling unit is electrically connected to the host computer.

[0022] Optionally, the measuring end of the temperature detection unit is a temperature sensor;

[0023] The temperature sensor is connected to the host computer via a data acquisition unit.

[0024] On the other hand, the present invention also provides a bipolar degradation screening test method for multi-device tandem mixed testing, the steps of which include:

[0025] S1. Determine at least some characteristic parameters of the silicon carbide device to be tested;

[0026] S2. The silicon carbide devices are divided into multiple groups according to type or model, and installed in the detection circuit accordingly;

[0027] S3. Apply current stress of a preset current switching sequence to the silicon carbide device, and control the test temperature of the silicon carbide device by linking the temperature detection unit with the cooling unit.

[0028] S4. The host computer detects abnormal situations online. When the abnormal situation occurs, the silicon carbide devices in the abnormal group are independently tested and screened, and the non-abnormal group is tested until the set test time.

[0029] Optionally, the characteristic parameters include the threshold voltage of the silicon carbide device or the temperature coefficient of the silicon carbide device;

[0030] The current switching switch includes a main switch and a bypass switch; a current source, a current meter, a voltmeter and the main switch are connected in series on the main circuit of the detection circuit; each detection position in the detection circuit is equipped with a bypass, and a constant current source and the bypass switch are connected in series on the bypass.

[0031] The current switch sequence consists of the main switch and the bypass switch being switched on and off alternately.

[0032] In step S3, when the bypass switch is turned on, the constant current source provides a temperature testing current to the silicon carbide device.

[0033] In S4, before each main switch is turned on, the host computer detects the total voltage drop or total on-resistance of the detection circuit online and records it as an intermediate value.

[0034] The abnormal situation refers to the occurrence of an intermediate value exceeding the threshold.

[0035] Compared with the prior art, the present invention, employing the above technical solution, has the following technical effects:

[0036] This invention employs a device-level bipolar degradation screening test method that uses multiple devices in series for mixed testing. The device drives the device under test to continuously conduct test current in the detection circuit under temperature control and measurement conditions, and collects data online during the test to screen and evaluate the bipolar degradation reliability of silicon carbide devices under specified current stress conditions, thereby improving the screening efficiency and accuracy of bipolar degradation testing of silicon carbide devices. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a simplified diagram of the device structure of the present invention;

[0039] Figure 2 This is a circuit diagram of the SiC MOSFET device detection circuit of the present invention;

[0040] Figure 3 This is a circuit diagram of the SiC SBD device detection circuit of the present invention;

[0041] Figure 4 This is a diagram of the current switching sequence in the method of this invention;

[0042] Figure 5 This is a flowchart of the method of the present invention.

[0043] In the diagram: 1. Silicon carbide device, 2. Test platform, 3. Temperature detection unit, 4. Cooling unit, 5. Current switch, 6. Data acquisition unit, 7. Controller, 8. Host computer. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0046] It should also be noted that, unless otherwise specified, the methods used in this invention are conventional methods; and the raw materials and apparatus used are, unless otherwise specified, conventional commercially available products.

[0047] like Figure 1 As shown, on one hand, the present invention provides a bipolar degradation screening test device for multi-device series mixed testing, which includes a host computer 8, a temperature detection unit 3, a cooling unit 4 and at least one set of detection circuits.

[0048] Among them, the host computer 8 serves as an information processing, analysis, and control unit. It integrates a control system and a data acquisition system on the hardware basis of a computer, server, or industrial control computer. It is electrically connected to the temperature detection unit 3, the cooling unit 4, and the detection circuit via cables. It can automatically control the switches, cooling unit 4, temperature detection unit, and other functional modules in the circuit according to preset information, and record relevant data, including temperature, time, electrical parameter test information, and results.

[0049] Cooling unit 4 employs either air cooling or water cooling; the specific cooling method chosen depends on the type of silicon carbide device 1 and the testing requirements. Its controller 7 is electrically connected to the host computer 8, and the cooling capacity is adjusted via the host computer 8. The cold end of cooling unit 4, such as an air-cooled radiator or a water-cooled head, is mounted on the test platform 2 and directly or indirectly contacts the package housing of the silicon carbide device 1 under test to control the test temperature.

[0050] The test platform 2 serves as a physical platform, carrying the load. It is equipped with at least one set of detection circuits, and the measuring end of the temperature detection unit 3, i.e., the temperature sensor, is installed on the test platform 2 to detect the temperature change of the silicon carbide device 1 shell during the test. The signal is transmitted to the host computer 8 through the matching data acquisition unit 6 for recording and analysis, and to obtain the temperature-sensitive parameters and junction temperature changes of the tested silicon carbide device.

[0051] In a specific single-group detection circuit, multiple silicon carbide devices 1 to be tested are connected in series, as shown in the reference. Figure 2 and Figure 3 Furthermore, the detection circuit is equipped with a current on / off switch 5, which is electrically connected to the host computer 8 to control its on / off state. Additionally, the current on / off switch 5 can be selected as a pulse modulation switch, so as to perform high-speed and precise on / off operations on the circuit using a PWM square wave.

[0052] Optional, see reference Figure 2 and Figure 3 As shown, the current on / off switch in a single detection circuit includes a main switch S1 and multiple bypass switches, such as bypass switches S2, ..., S... n-2 S n-1 S n (n is a natural number greater than 2);

[0053] Specifically, a current source, a galvanometer, and a main switch S1 are connected in series in the main circuit of the detection circuit; wherein, the current source in the main circuit is used to provide the main circuit current I for testing. on A voltmeter is also installed on the main circuit of the detection circuit. The voltmeter is connected across all detection positions of the detection circuit and is not affected by the main switch S1.

[0054] Each detection position in each detection circuit is equipped with a silicon carbide device, and a corresponding bypass is provided, with a constant current source and a bypass switch connected in series on the bypass. Accordingly, there are n-1 detection positions; the constant current source provides the bypass current I for individual component temperature measurement. sense .

[0055] like Figure 5 As shown, the present invention also provides a bipolar degradation screening test method based on the aforementioned device for multi-device tandem mixed testing, the main steps of which include:

[0056] S1. Determine at least some characteristic parameters of the silicon carbide device to be tested; wherein, the silicon carbide devices applicable to this invention include, but are not limited to, SiC diodes, SiC MOSFET body diodes without anti-parallel diodes, and SiC IGBT discrete devices. Therefore, the characteristic parameters can be selected according to the different test objects, such as the threshold voltage of the silicon carbide device (determining the gate-source voltage V at which the channel is completely closed). GS(off)(Only needed when screening SiC MOSFET body diode bipolar degradation) or temperature coefficient of silicon carbide devices.

[0057] S2. Initially measure the total voltage drop V of the group of silicon carbide devices at the test temperature. DS(on)0 / V F0 / V CE(on)0 Or total on-resistance R DS(on)0 / R d0 / R CE(on)0 .

[0058] Wherein, the subscript 0 represents the initial measurement, and the total voltage drop is expressed differently depending on the test object. Specifically, in the degradation test circuit, it can represent: V DS(on) V represents the voltage between the drain and source of a MOSFET when it is turned on. F V represents the forward voltage drop of a diode. CE(on) This represents the voltage between the collector and emitter of the IGBT when it is conducting; similarly, the total on-resistance in the degradation test circuit can specifically represent: R DS(on) R represents the resistance between the drain and source of a MOSFET when it is turned on. d R represents the on-resistance of a diode. CE(on) This represents the resistance when the collector-emitter junction of the IGBT is turned on.

[0059] The silicon carbide devices are grouped according to type or model and installed in the detection circuit accordingly. Device parameters are set, such as time parameters and the test start time t. on Stop time t off and initial cooling capacity Q _cool To ensure that the junction temperature of the device does not exceed the maximum junction temperature specified in the product specification during the testing and screening process, it should generally not exceed 100℃.

[0060] S3. Apply current stress to the silicon carbide device using a preset current switching sequence; optionally, the current switching sequence alternates between the main switch and the bypass switch, such as... Figure 4 As shown, the test time is divided into a single cycle for repeated execution; each cycle includes two time periods: the first time period is when the main switch is on and the bypass switch is off; the second time period is when the main switch is off and the bypass switch is on. In the diagram, 0-t2 represents one complete cycle, where 0-t1 is the first time period, during which the main circuit current I exists. on The bypass current is 0; t1-t2 is the second time period, during which a bypass current I exists. sense Main circuit current I on The value is 0, the purpose of which is to bypass the switches (S2, ..., S...). n-2 S n-1 S n When switched on, the constant current source provides a temperature testing current (i.e., bypass current I) to the silicon carbide device. senseBefore each main switch S1 is turned on, the host computer detects the total voltage drop or total on-resistance of the detection circuit online and records it as an intermediate value.

[0061] This step mainly utilizes the SiC device detection circuit and current switching sequence to apply current stress to the body diode, SiC diode, and SiC IGBT of the SiC MOSFET reverse diode.

[0062] S4. When an abnormality occurs in the online detection of the host computer, that is, when an intermediate value exceeds the threshold, such as: the i-th intermediate value measured online before the i-th main switch is turned on: V DS(on)i / V Fi / V CE(on)i Or R DS(on)i / R di / R DS(on)i If the failure criterion is exceeded, the host computer immediately checks each device, short-circuits the abnormal device, and performs individual testing and analysis on the abnormal device. Meanwhile, the remaining silicon carbide devices in the group and the non-abnormal group continue testing until the set testing time (i.e., the stop time t) is reached. off The host computer then sent another command to pause the test.

[0063] Example 1: Screening of 100 silicon carbide metal-oxide-semiconductor field-effect transistors (hereinafter referred to as SiCMOSFETs) through bipolar degradation testing;

[0064] S1. Determine the gate-source voltage V at which the channel is completely closed. GS , denoted as V GS(off) And calibrate the temperature coefficient of SiC MOSFET.

[0065] S2. Divide the 100 SiC MOSFETs into 10 groups of 10 each, and name each group #1, #2, #3, #4, #5, #6, #7, #8, #9, and #10. Initially, measure the total voltage drop V of each group of SiC MOSFETs at the test temperature. DS(on)0 Or total on-resistance R DS(on)0 / R d0 / R CE(on)0 .

[0066] Each SiC MOSFET is placed at its respective detection position in the aforementioned device, and the detection circuit is as follows: Figure 2 As shown, and set the parameter t. on t off and Q _cool Ensure that the junction temperature of the device does not exceed the maximum junction temperature specified in the product specification during the screening test.

[0067] S3. Between time points 0 and t1, the main switch S1 is turned on, and the bypass switches S2 to S...n When the gate of the SiC MOSFET is turned off, a negative voltage is applied, the channel is closed, and the body diode of the SiC MOSFET device is turned on; between time points t1 and t2, the main switch S1 is turned off, and the bypass switches S2 to S... n When the SiC MOSFET is turned on, it is turned off. A negative voltage is applied to the gate, and the channel is closed. A constant current source is used to apply a temperature test current I to the body diode of the SiC MOSFET device. sense ; repeating this cycle, assuming the abnormal situation occurs during online measurement before the i-th start-up, its V DS(on)i Or R DS(on)i / R di / R DS(on)i As the i-th intermediate value.

[0068] S4. If the i-th intermediate value of group #5 exceeds the failure criterion, the host computer will immediately short-circuit the abnormal device and conduct independent testing on the abnormal device. The remaining SiC MOSFETs in the group will continue to be tested. If no intermediate value in any group exceeds the failure criterion, the test will stop when the specified test time is reached.

[0069] Example 2: Screening of 1000 silicon carbide Schottky diodes (SiC SBDs, hereinafter referred to as SiC diodes) through bipolar degradation testing;

[0070] S1, calibrating the temperature coefficient of the SiC diode.

[0071] S2. Divide the 1000 SiC diodes into 40 groups of 25 each, and name each group #1, #2, #3, #4, #5, ..., #37, #38, #39, #40. Initially, measure the total voltage drop V of each group of SiC diodes at the test temperature. F0 Or total on-resistance R d0 .

[0072] Each SiC diode is placed at its respective detection position in the above device, and the detection circuit is as follows: Figure 3 As shown, and set the parameter t. on t off and Q _cool Ensure that the junction temperature of the device does not exceed the maximum junction temperature specified in the product specification during the testing and screening process.

[0073] S3. Between time points 0 and t1, the main switch S1 is turned on, and the bypass switches S2 to S... n When the main switch S1 is turned off, the PN junction of the SiC diode opens and it conducts in the forward direction; between time points t1 and t2, the main switch S1 is turned off, and the bypass switches S2 to S... n When the diode is turned on, a constant current source is used to apply a temperature test current I to the SiC diode. senseThe junction temperature is obtained; this cycle is repeated, assuming the abnormal situation occurs before the i-th start-up, the online measurement is V. Fi Or R di As the i-th intermediate value.

[0074] S4. If the i-th intermediate value of group #12 exceeds the failure criterion, the abnormal device is immediately short-circuited, and the remaining SiC diodes in the group continue to be tested. If no intermediate value of any group exceeds the failure criterion, the test is stopped when the specified test time is reached.

[0075] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A bipolar degradation screening test device for multi-device tandem mixed testing, characterized in that, It includes a host computer, a temperature detection unit, a cooling unit, and at least one set of detection circuits; the host computer is electrically connected to the temperature detection unit, the cooling unit, and the detection circuits respectively; The cold end of the cooling unit is provided with a test platform, the test platform is equipped with the detection circuit, and the measuring end of the temperature detection unit is installed on the test platform. A single detection circuit contains multiple silicon carbide devices to be tested connected in series, and the detection circuit is equipped with a current on / off switch.

2. The bipolar degradation screening test device for multi-device tandem mixed testing according to claim 1, characterized in that, The current switching switch includes a main switch; A current source, a galvanometer, and the main switch are connected in series on the main circuit of the detection circuit. A voltmeter is also installed on the main circuit of the detection circuit.

3. The bipolar degradation screening test device for multi-device tandem mixed testing according to claim 2, characterized in that, The current switching switch includes a bypass switch; Each detection position in the detection circuit is equipped with a silicon carbide device and has a bypass, with a constant current source and the bypass switch connected in series on the bypass.

4. The bipolar degradation screening test device for multi-device tandem mixed testing according to claim 3, characterized in that, The voltmeter is connected across all the detection bits of the detection circuit.

5. The bipolar degradation screening test device for multi-device tandem mixed testing according to claim 3 or 4, characterized in that, The current switching switch is a pulse modulation switch.

6. The bipolar degradation screening test device for multi-device tandem mixed testing according to claim 1, characterized in that, The cooling unit is an air-cooled or water-cooled device; The cold end of the cooling unit directly or indirectly contacts the housing of the silicon carbide device.

7. The bipolar degradation screening test device for multi-device tandem mixed testing according to claim 6, characterized in that, The controller of the cooling unit is electrically connected to the host computer.

8. The bipolar degradation screening test device for multi-device tandem mixed testing according to claim 1, characterized in that, The measuring end of the temperature detection unit is a temperature sensor; The temperature sensor is connected to the host computer via a data acquisition unit.

9. A bipolar degradation screening test method for multi-device tandem mixed testing, characterized in that the steps are as follows: include: S1. Determine at least some characteristic parameters of the silicon carbide device to be tested; S2. The silicon carbide devices are divided into multiple groups according to type or model, and installed in the detection circuit accordingly; S3. Apply current stress of a preset current switching sequence to the silicon carbide device, and control the test temperature of the silicon carbide device by linking the temperature detection unit with the cooling unit. S4. The host computer detects abnormal situations online. When the abnormal situation occurs, the silicon carbide devices in the abnormal group are independently tested and screened, and the non-abnormal group is tested until the set test time.

10. The bipolar degradation screening test method for multi-device tandem mixed testing according to claim 9, characterized in that, The characteristic parameters include the threshold voltage of the silicon carbide device or the temperature coefficient of the silicon carbide device. The current switching switch includes a main switch and a bypass switch; a current source, a current meter, a voltmeter and the main switch are connected in series on the main circuit of the detection circuit; each detection position in the detection circuit is equipped with a bypass, and a constant current source and the bypass switch are connected in series on the bypass. The current switch sequence consists of the main switch and the bypass switch being switched on and off alternately. In step S3, when the bypass switch is turned on, the constant current source provides a temperature testing current to the silicon carbide device. In S4, before each main switch is turned on, the host computer detects the total voltage drop or total on-resistance of the detection circuit online and records it as an intermediate value. The abnormal situation refers to the occurrence of an intermediate value exceeding the threshold.

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