Patent ID: 9577073
Date: 2017-02-21
CPC Classifications: H01L

Claim:
1. A method of forming a semiconductor device, comprising: forming a silicon-carbide semiconductor substrate having a plurality of first doped regions being laterally spaced apart from one another and beneath a main surface of the substrate, a second doped region extending from the main surface to a third doped region that is above the first doped regions, and a plurality of fourth doped regions in the substrate extending from the main surface to the first doped regions, the second doped regions having a first conductivity type, the first, third and fourth doped regions having a second conductivity type; annealing the substrate so as to activate dopant atoms in the second, third and fourth doped regions; forming a gate trench that extends through the second and third doped regions and has a bottom that is arranged over a portion of one of the first doped regions; applying a high-temperature step in a non-oxide and non-nitride forming atmosphere so as to realign silicon-carbide atoms along sidewalls of the gate trench and to form rounded corners between the bottom and sidewalls of the gate trench; and removing a surface layer that forms along the sidewalls of the gate trench during the high-temperature step from the substrate.