This paper deals with the breakdown voltage studies on a new lateral diffusion p‐channel MOSFET(LDMOS) and development of an optimal structure based on the breakdown voltage and on‐state resistance. In this new structure, the channel region (n‐body) and the lightly doped drain (LDD) structure were formed by a self‐aligned process. This approach leads to the saving of one mask level during fabrication. Two‐dimensional simulation was carried out on various parameters such as the horizontal and vertical electric field intensities, the impact generation profiles, generation recombination, impact generation before and after breakdown, the carrier concentration, electron and hole current densities and the conduction current densities of the structure to ascertain the behaviour of breakdown voltage and the on‐state resistance. Breakdown voltages closer to −162 V have been obtained in these structures.