Novel Bulk Silicon Lateral Double-Diffused Metal--Oxide--Semiconductor Field-Effect Transistors Using Step Thickness Technology in Drift Region

In this paper, a novel bulk silicon lateral double-diffused metal--oxide--semiconductor field-effect transistors (LDMOS) using step thickness technology in drift region is proposed. The drift region is divided into several zones with different thicknesses increasing from source to drain. Owing to modulation effect of the step thickness drift region, new additional electric field peaks are introduced in the drift region, thus leading to the reduction of the surface electric fields and the increase of the breakdown voltage. The influences of device parameters on breakdown voltage and specific on-resistance are investigated using semiconductor device simulator, MEDICI. The simulation results indicate that an 18.4% increase in the breakdown voltage and a 42.5% increase in the figure of merit (FOM) are obtained in the novel device in comparison with the conventional LDMOS. Furthermore, single step can lead to approximately ideal FOM in comparison with the multiple steps, so that can obtain a suitable trade-off between fabrication costs and performance.