Research On Methods Of Offset Field Plate And Field-Limiting Ring Termination Structure

There are two parts in the work of this thesis: researches on field-limiting ring (FLR) termination structure and field plate (FP) termination structure. Firstly we present and compare three methods of FLR termination design existed presently in detail. Multiple exhausting method has little practicability because of its complexity and long-time exhausting. The advantage of local ionization integral method lies in its high precision. But this method is too complex compared with our method and it exhausts a long computing time. The author compiled an algorithm to accelerate convergence speed. This method has a special requirement on simulation software, so its application is limited. The advantage of our method is its simplicity, practicability and small calculation. We can obtain the BV-distance curve from the results of the breakdown-characteristic simulation of a simple single-ring model. Then we can obtain the complete FLR termination structure form this curve. Our method has no special requirement on software so it is applicable to common device simulation software. The simulation result and experiment data show that using our method we can achieve very high precision that is approximately the same as local ionization integral in middle voltage range.Interface charge has a profound influence on the breakdown voltage of FLR structure. On severe condition it can make the outer FLR far from main junction disfunction. In order to adapt this method to practical device manufacture we investigate the design method of offset FP structure that is the combination of FLR structure and FP structure. With offset FP structure obtained by using our method the device breakdown voltage is higher than FLR structure, and this structure can screen the influence of interface charge in part and improve the stability of device performance.