Patent ID: 7942974

Claim:
A method for etching a silicon-based material deposited on a constituent member of a film-forming apparatus, comprising: forming a cleaning gas consisting essentially of F 2 gas, CO gas, and a diluent gas by separately introducing said F 2 gas, said CO gas, and said diluent gas into said apparatus; heating said constituent member present in said apparatus to a temperature within the range of 100° C. to 300° C.; and while the constituent member is at a temperature within the range of 100° C. to 300° C., contacting the heated constituent member with said cleaning gas to selectively etch said silicon-based material deposited on said constituent member, wherein the silicon-based material comprises silicon nitride and the constituent member comprises quartz, and wherein a flow rate ratio of the CO gas to the F2 gas is 0.11 to 0.20 such that the cleaning gas selectively etches silicon nitride from quartz.