LDMOS Drift Region With Field Oxides: Figure-of-Merit Derivation and Verification

We analytically and numerically investigate the performance of Laterally-Diffused Metal-Oxide-Semiconductor (LDMOS) transistors with Semi-circular Field OXide (S-FOX) focusing on mid-voltage (30 V – 100 V) power applications. We derive an analytical relation between breakdown voltage and on-resistance to realize the ideal behavior of the drift region for an LDMOS with S-FOX. Then, we find the optimized drift doping concentration minimizing the on-resistance at a given breakdown voltage. We introduce a new figure-of-merit for the drift region of a lateral device with S-FOX. We finally verify our ideal analytical findings with numerical results modeled and simulated in a commercial Technology Computer-Aided Design (TCAD).