US Patent 9865471 Etching method and etching apparatus

A method for etching a silicon film formed on a substrate includes supplying HBr gas, NF3 gas, and O2 gas into a chamber and performing a plurality of etching processes on the silicon film with a plasma generated by the supplied HBr gas, NF3 gas, and O2 gas, gradually reducing a flow rate of the HBr gas during the plurality of etching processes, and adjusting a flow rate of the O2 gas according to the reduction of the HBr gas.