A Novel Variation of Lateral Doping Technique in SOI LDMOS With Circular Layout

The breakdown characteristics of a practical silicon-on-insulator (SOI) lateral power device are generally limited by the 3-D curvature effect induced by its circular layout. The Conventional 2-D design methods such as 2-D variation of lateral doping (VLD) technique cannot derive optimal device parameters. In this paper, for the first time, a 3-D VLD technique is proposed to suppress the 3-D curvature effect in the lateral power device with circular layout. The 3-D Poisson equation is solved to formulate the optimized doping profile. TCAD tools are employed to verify the model and explore the physic insight. By adding an inversely proportional doping profile onto the conventional linear doping profile, the analytical and numerical results show that the uniform electric field in the drift region and maximized breakdown voltage (BV) are obtained for the SOI lateral double-diffused metal-oxide-semiconductor with circular layout. Furthermore, compared to the 2-D VLD device, the proposed 3-D VLD technique also contributes to excellent on-state characteristics, including the high on-state BV, reduced specific on-resistance, large saturation current, suppressed quasi-saturation effect, improved transconductance, and thus a large Baliga's figure of merits (BFOM).