Abstract
In recent years, device has become smaller gradually. Due to the reason the problem of hot-carrier effect becomes more and more important. So in this thesis we study the substrate current and reliability of LDMOSFET. In this thesis we use the BCD 0.6um process and the operate voltage on drain and gate are both 15 volts. We find a new phenomenon of substrate current. There is a second substrate current hump (SSCH) appears. We use TCAD (Tsuprem4 and Medici) to understand and analysis the strange phenomenon. At last we judge the effect of SSCH in this device and try to improve the performance. In this thesis we make a basic theory of the substrate current.