Abstract
In recent years, following the introducing of state of the art electronic products, demands for power devices have risen substantially. In order to integrate power devices with planar IC process, traditional vertical device needs to be changed to lateral structure. The most commonly used lateral power device is LDMOSFET. Most of the improvements of power device need to increase the cost. Getting better device performance without increasing the cost is often a difficult job. In this thesis, we integrate floating field plate into 400V LDMOSFET and get larger breakdown voltage without raising the cost. At the same doping concentration of the epitaxy layer, it can get 74.5V higher than the conventional structure. We also use simulation tools to analyze the effect of floating field plate in LDMOSFET and get optimal design finally.