Model Study And Bevel Edge Termination Design For 4H-SiC RSD

The development of modern pulsed power technology increasingly requires higher operating frequency, higher operating temperature and higher operating voltage. As the key technology of the pulsed power system, switching device is more focused on the device characteristics of low-loss, high voltage, high power, high repetition rate and long service life. Using Si C materials to make RSD can improve the blocking voltage and current density of the device, reduce conduction losses in high blocking voltage condition. And these advantages will make the Si C RSD device more valuable in high voltage and repetition frequency applications.This paper has studied blocking characteristics, positive-bevel edge termination, on-state characteristics and thermodynamic model of the 4H-Si C RSD. The main results are as follows:This paper has studied the relationship between the forward blocking voltage and the parameter of N-base region. In order to improve the forward blocking voltage characteristics, the positive-bevel edge termination is designed. By establishing the two-dimensional numerical model, the function that the positive-bevel can reduce the surface electric field is proved. Combined the surface electric field and the area loss, 45 degree positive angle is selected. According to the process characteristics of Si C material, bevel dicing together with ICP(inductively coupled plasma) etching treatment is chosen to fabricate the positive-bevel edge termination in experiment. The forward blocking voltage of about 600 V is acquired for the device. The optimal value for the etching depth is also discussed.Based on the two-dimensional numerical model, this paper has studied on-state characteristics of 4H-Si C RSD. First, compared with Si RSD and Si C RSD, simulation results show that Si C RSD has a excellent on-state characteristics than Si RSD at the same high forward blocking voltage(above 6k V). Second, this thesis tries to optimize the lifetime of the N-base region's electron, simulation results shows that the lifetime is at least 1?s. Third, this thesis also studies the pre-charge of 4H-Si C RSD, the results shows that 4H-Si C RSD has a smaller pre-charge than that of Si RSD, the main reason is that 4H-Si C RSD has a thinner P base region.In order to analysis the thermal effect, this thesis has also established a Thermodynamic Model. When the device is working normally, the temperature distribution and the temperature rise in the process of on-state are reasonable. When the temperature rises to 1800K(Intrinsic Temperature), the device's power can reach more than a dozen MW·cm-2?...