Patent ID: 9633840
Date: 2017-04-25
CPC Classifications: C23C,H01L

Claim:
1. A method of manufacturing a silicon carbide semiconductor substrate, comprising steps of: preparing a silicon carbide substrate; forming a first silicon carbide semiconductor layer on the silicon carbide substrate using a first source material gas; and forming a second silicon carbide semiconductor layer on the first silicon carbide semiconductor layer using a second source material gas, wherein an impurity concentration in the first silicon carbide semiconductor layer is higher than an impurity concentration in the second silicon carbide semiconductor layer, in the step of forming a first silicon carbide semiconductor layer and the step of forming a second silicon carbide semiconductor layer, ammonia gas being used as a dopant gas, the first source material gas having a C/Si ratio of not less than 1.6 and not more than 2.2, the C/Si ratio being the number of carbon atoms to the number of silicon atoms, a flow rate of the first source material gas being different from a flow rate of the second source material gas.