An optimal variation in lateral doping profiles is proposed for the drift region of lateral power devices in partial SOI technology in order to achieve breakdown voltage above 200V for both off-state and on-state operations. LDMOS structure incorporating the proposed optimal doping profile are analyzed for their electrical characteristics and compared with conventional uniformly doped SOI and thin layer SOI by extensive 2D numerical simulations using MEDICI. The results indicate that the proposed optimal doping profile is in good agreement with the optimal doping gradient for JI technology. The optimal doping gradient can significantly improve the trade-off between breakdown voltage and specific on-resistance in comparison to uniformly doped SOI. In this study we also show a physical method to design SOI device with linear doping profile. A drift region with linear thickness (LT) is proposed to uniform the lateral electric fields and increase impurity levels. The linear thickness (LT) device using the physical method delivers a significant reduction of the on-resistance without compromising the breakdown voltage capability in comparison with the lateral linear doping technology. Therefore, the new LDMOS provides an excellent BFOM value, which is double of conventional RESURF devices and linear doping devices. Furthermore, improved kink and quasi-saturation effects are also found in the linear thickness (LT) device , thus resulting in an optimal safe operating area.
