1000h SiC MOSFET Body Diode Reliability Report

“Silicon carbide power devices break through the performance limit of silicon power devices and can be used in harsh environments such as high temperature, high frequency, high voltage, and high current, while improving system efficiency and reducing system costs. However, the harsh application environment makes the reliability of silicon carbide power devices face severe challenges. Since the reliability test research for different characteristics of silicon carbide device materials is not yet mature, the reliability test of silicon carbide power devices basically follows the reliability test method of silicon power devices.

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Silicon carbide power devices break through the performance limit of silicon power devices and can be used in harsh environments such as high temperature, high frequency, high voltage, and high current, while improving system efficiency and reducing system costs. However, the harsh application environment makes the reliability of silicon carbide power devices face severe challenges. Since the reliability test research for different characteristics of silicon carbide device materials is not yet mature, the reliability test of silicon carbide power devices basically follows the reliability test method of silicon power devices. The band gap of silicon carbide material is larger than that of silicon material, and the forward voltage drop VF of the body diode of SiC MOSFET is larger than that of Si MOSFET body diode, resulting in an increase in the power consumption of the body diode freewheeling, Therefore, the reliability of the SiC MOSFET body diode deserves more attention. At present, there are few research papers and reports on the reliability of the body diode of SiC MOSFET. This paper studies the reliability of the body diode of SiC MOSFET.

experiment procedure

According to the JEDEC standard, Pinjie built a test platform that can test the reliability of multiple SiC MOSFET body diodes at the same time. As shown in Figure 1, negative pressure is applied to the gate of each device, and air cooling is used for heat dissipation. The reliability of the SiC MOSFET body diode was studied by observing the degradation of the forward conduction capability and reverse blocking capability of the SiC MOSFET body diode by passing DC current to the SiC MOSFET body diode for a long time. This platform can collect the case temperature of the device and then control the fan speed through the host computer to automatically test different chip junction temperatures.

Figure 1. Body Diode Reliability Test Platform

In this paper, Pinejie 1200V 80mΩ 3pin SiC MOSFET P3M12080K3-732303 is used for body diode reliability test. The test conditions are Vgs=-5V, Isd=5A. Through the thermal imager, the case temperature of the device reaches about 130 °C, as shown in Figure 2. Through the formula Tj=Tc+Rjc*Pd, the junction temperature of the device can be estimated to be around 150℃, where Tj is the device junction temperature, Tc is the device case temperature, Rjc is the device junction-to-case thermal resistance, and Pd is the power applied to the device.

Figure 2. P3M12080K3 Body Diode Reliability Case Temperature

After the P3M12080K3 body diode is applied with 5A DC current for 1000h, the typical point value threshold voltage Vth, on-resistance Rdson, withstand voltage Bvdss and body diode forward voltage drop VFSD change rate are shown in Figure 3, Figure 4, Figure 5, Figure 6 . It can be seen that the change rates of Vth, Rdson, Bvdss and VFSD are all small and all meet the specification.

Figure 3. Vth rate of change over time

Figure 4. Rdson rate of change over time

Figure 5. Bvdss rate of change over time

Figure 6. VFSD rate of change over time

After the P3M12080K3 body diode is applied with 5A DC current for 1000h, the changes of the withstand voltage curve, transfer curve, output curve, and VFSD curve are shown in Figure 7, Figure 8, Figure 9, and Figure 10. It can be seen that the change of the curve with time is small, and the performance of the device is stable.

Figure 7. 1000h withstand voltage curve change

Figure 8. 1000h transfer curve change

Figure 9. 1000h output curve change

Figure 10. 1000h VFSD curve change

The P3M12080K3 body diode has been tested for 1000h DC reliability, and the performance degradation of the device is relatively small, and the change rate of device parameters is far below the 20% failure standard. The P3M12080K3 works at a high junction temperature for a long time, and the device performance is less degraded, which shows that the performance of the Pinjie SiC MOSFET power device is stable and reliable.