4H–SiC Lateral Double RESURF MOSFETs With Low on Resistance

Designing and fabrication of 4H-SiC (0001) lateral MOSFETs with a double reduced surface field (RESURF) structure have been investigated to reduce ON resistance. In order to achieve high breakdown voltage, a two-zone RESURF structure was also employed in addition to the double RESURF structure. The simulated double RESURF MOSFETs with optimum doses exhibit slightly higher breakdown voltage and lower drift resistance than the simulated single RESURF MOSFETs. The double RESURF structure is attractive to suppress oxide breakdown at gate edge. After the device simulation for dose optimization, the 4H-SiC two-zone double RESURF MOSFETs have been fabricated by using a self-aligned process. The fabricated MOSFET has demonstrated a high breakdown voltage of 1380 V and a low ON resistance of 66 mOmegamiddotcm² (including a drift resistance of 24 mOmegamiddotcm²). The drift resistance of the fabricated double RESURF MOSFETs is only 50% or even lower than that of the single RESURF MOSFETs