Studies on the dependence of breakdown voltages LDMOS devices on their structure and doping profiles of LDD regions

LDMOS (lateral double diffused power MOSFET) devices are an important class of devices finding applications in high voltage and smart power applications. Compared to conventional MOSFETs these devices make use of extended low doped drain regions extending under a thick oxide to improve breakdown properties. The doping profiles of the drain drift region, the p channel region and the length of the drift region play an important role in determining the breakdown properties and on state resistances of these devices. In this work the dependence of the breakdown voltage on the device structure and doping profiles is studied based on device and process simulation. Doping profile are changed by changing the implant dose and time of diffusion. Also studied is the variation of the drift length in the LDD region. The structure has been simulated using a process simulator and device characteristics were obtained using a device simulator. Breakdown voltages in the range of 50V to 96 V have been obtained for different structures.