Research On The High Voltage And Fast Soft Recovery Diode

The power devices towards to the large capacity and high frequency, which makes more stringent requirements of the freewheeling diode. Because of the most abundant silicon materials in the natural, power devices based on it will still be the mainstream one in a quite long time. Therefore, it is very important to study the fast and soft recovery technology of silicon based power diode in order to further optimize or improve the device structure.The silicon power diode reverse recovery characteristics are briefly introduced in this paper. In order to obtain soft turn off characteristic, the key lies in the realization of the reversal of the internal device carrier distribution. On this basis, we put forward a field charge extraction diode structure. The structure in the cathode was improved, on the cathode part introduced P+ layer. At the end of turn-off, the hole of the P+ layer is injected by the interaction of the electric field inside the device, which makes the diode slow down the reverse recovery current rate. By this method, to the soft switching characteristics is obtained. At last, the measure of power diode reverses recovery characteristic parameters is briefly introduced.Then, the structure design is discussed from the diode structure. Theoretically we discuss the relationship between the devices reverse recovery properties and structure, and gives their mathematical formula. On this basis, a 150 A /1200 V field charge extraction diode structure is designed, which is wizard through characteristics, reverse blocking performance and reverse recovery characteristics by using numerical method simulation. It shows that, field charge extraction diode structure can achieve fast and soft turn-off, smaller losses than the carrier lifetime diode technology.Then, the reverse recovery characteristics of the field charge extraction diode structure is discussed. The change of the reverse recovery characteristics are discussed under the low temperature and the high commutation rate. It shows that under the above conditions, the field charge extraction diode can still achieve soft turn-off, and has strong ability of dynamic avalanche. Finally, the device structure parameters are optimized, so the reverse characteristics of the device can reach the optimum.Based on the structure research, the fabrication process of the field charge extraction diode is discussed. Due to the complexity of the cathode structure, we propose the process scheme of diffusion method; design the field of charge pumping diode process. By using numerical simulation technology, the whole process is simulated. After the completion of the production process, devices of various characteristic parameters are verified. The results show that the parameters of the device are in line with the expected design, which indicates that the process is feasible.Finally, the research results show certain reference value and practical significance for the design and development of high voltage fast soft switching diode.