Dose Designing and Fabrication of 4H-SiC Double RESURF MOSFETs

Designing and fabrication of 4H-SiC (0001) lateral MOSFETs with a double reduced surface field (RESURF) structure have been investigated to reduce a drift resistance. In order to achieve high breakdown voltage, a two-zone RESURF structure was also employed in addition to the double RESURF structure. After device simulation for dose optimization, 4H-SiC two-zone double RESURF MOSFETs have been fabricated by using an original self-aligned process proposed in this paper. The fabricated MOSFETs with optimum doses exhibit a high breakdown voltage of 1380 V and a low on-resistance of 66 mOmegam² (including a drift resistance of 13 mOmegacm²). The drift resistance in the fabricated MOSFETs with double RESURF structure is only 50 % or even lower than that in the MOSFETs with a normal RESURF structure. The figure-of-merit (V_B2/R_ON) of the present device reaches 29 MW/cm², which is the best performance among any lateral MOSFETs ever reported