A dry etching method for 4H-SiC via using photoresist mask

In this abstract, a novel method of 4H-SiC shallow trench etching process via directly using photoresist as a mask is proposed to fabricate SiC MOSFETs and SiC diodes which enjoy popularity in power devices. By changing the profile of photo resist mask during exposure and development, with SF6/O-2 plasma alternatively attacking onto the SiC surface, different shallow trench taper angles from 45 degrees to 85 degrees are achieved. The described shallow trench process plays a vital role in alignment mark, declined ion implantation and JTE structure fabrication process of power device R&D and manufacturing. With the proposed method, we have successfully fabricate a 1200 V/20A SiC SBD device with breakdown voltage of 1400 V (@I-R = 10 mu A), and threshold voltage of 1.6 V (@ I-F = 20 A), yield of 98% and uniformity less than 3% from wafer to wafer. Moreover, using photoresist directly as a SiC etching mask simplifies the etching process compared with the traditional two masks process and thus saves mass production cost and tact time.