An Analytical Breakdown Model for the SOI LDMOS With Arbitrary Drift Doping Profile by Using Effective Substrate Voltage Method

To elaborate on the relationship between sophisticated 2-D doping profile of drift region and device’s breakdown behavior, a unified analytical model for the SOI LDMOS is developed in this paper. The Effective Substrate Voltage (ESV) concept is proposed so that the derivation of electric field and breakdown voltage can be simplified significantly. The ESV indicates that the influence of 2-D doping in the drift region can be equivalent to a virtual substrate potential. By using the proposed model, the role of 2-D drift doping, both continuous or discrete doping profile, in SOI LDMOSs’ off-state breakdown behavior is investigated along with the TCAD simulations and experimental results. The good agreement between the analytical, measured and simulated results validates the accuracy of the developed model. A unified RESURF criterion is derived to idealize the electric field in the drift region and therefore maximize the breakdown voltage by optimizing the lateral and vertical drift doping profiles and geometric parameters. The proposed approach provides a universally applicable tool to explore the breakdown mechanism of SOI LDMOS with various drift doping profiles.