New High Voltage SJ-LDMOS with Non-uniform N-buried Layer

A novel super junction LDMOS (SJ-LDMOS) structure is proposed to eliminate the substrate-assisted depletion effect. The key feature of this new structure is that a non-uniform N-buried layer is implemented between the SJ region and P substrate which provides a uniform distribution of surface electric field and ensures the heavily doped n pillars extending over the entire drift region, allowing high breakdown voltage and ultra low on-resistance. Numerical simulation results indicate that the proposed device features high breakdown voltage, low on-resistance and reduced sensitivity to doping imbalance in the pillars. In addition, the proposed device is compatible with smart power technology.