A Lateral Double-Diffusion Metal Oxide Semiconductor Device with a Gradient Charge Compensation Layer
In order to better shield the substrate-assisted depletion (SAD) effect and improve the breakdown voltage of super-junction (SJ) devices, an SJ lateral double-diffusion metal oxide semiconductor device with a gradient charge compensation layer (gradient device) is proposed. The main feature of this structure is to introduce a gradient charge compensation layer between the SJ layer of a conventional device and the substrate. The depth of the gradient charge compensation layer increases gradually from the source to the drain. The charge distribution in the drift region is optimized by reducing the compensation charge on the side near the source and increasing the compensation charge on the side near the drain. Introduction of the layer improves shielding of the SAD effect, and the electric field on the surface of the structure is an approximately rectangular distribution, thus the breakdown voltage is improved. The simulation results show that the gradient device has 409-V breakdown voltage and a 9.5-MW cm−2 figure of merit with a drift region length of 21 μm. Compared with the conventional SJ structure (conventional device) with the same drift length, the breakdown voltage and figure of merit of the gradient device are increased by 57.3% and 137.5%, respectively.