An Analytical Model of the Electric Field Distribution and Breakdown Voltage for Stepped Compound Buried Layer SOI LDMOS

For the first time, an analytical model for the electric field distribution and breakdown voltage (BV) of a novel siliconon-insulator (SOI) reduced surface field (RESURF) laterally double-diffused metal oxide semiconductor (LDMOS) with a partial stepped polysilicon and oxide compound buried layer (SPCBL) structure is presented. By establishing and working out the two-dimensional (2D) Poisson equation, the device electric field distributions, together with the potential distributions, are derived, and the BV is calculated. According to the proposed model for the SP-CBL device, the electric potential distribution is strongly influenced by the thickness of the top buried oxide layer. Therefore, the stepped polysilicon structure can make a difference in the modulation of the distribution of the electric field and enhance the BV. The results of the proposed analytical model are in agreement with those of the 2D numerical simulation using technology computer-aided design (TCAD) tools. The proposed analytical model offers a clear guiding function for power device optimization and design and is also suitable for other dielectric field-enhanced power electronic devices.