A method for manufacturing a silicon carbide (SiC) semiconductor device is disclosed that uses dry etching with the use of high-density inductive coupled plasma (ICP). The method employs a first dry etching and a sequential second dry etching under conditions that differ from those used in the first dry etching. The dry etch process allows a trench to be deeply etched to a depth of more than 3 .mu.m in a SiC laminated semiconductor substrate and allows the bottom of the trench to be flat without forming a convexo-concave shape having an acute angle which has an influence on characteristics of a breakdown voltage due to electric field concentration being caused in the bottom.