PURPOSE: To avoid corrosion of pipes, valves and so forth of a dry etching equipment and facilitate improving the utilization factor of the equipment and reducing the maintenance cost by a method wherein unsaturated hydrocarbon gas is made to flow so as to be contacted with a wall surface to which free bromine adheres to remove the adhering bromine from the wall surface.

CONSTITUTION: By making unsaturated hydrocarbon gas flow so as to contact the gas with a wall surface to which bromine adheres, the adhering bromine is removed from the wall surface. For instance, after several to several-ten times of etching are completed by a dry etching equipment, the insides of the reaction chamber 1 and the pipe 7 of the equipment are evacuated. Then, if unsaturated hydrocarbon gas such as ethylene is made to flow from a bomb 12 by itself or with diluting gas such as nitrogen, bromine adhering to the wall surfaces of the reaction chamber 1, a valve 6 and the pipe 7 is converted into unsaturated hydrocarbon bromide and removed from the wall surfaces and eliminated. Successively, inert gas such as nitrogen or argon is supplied from a bomb 15 while the inside of the pipe 7 is evacuated to exhaust the remaining unsaturated hydrocarbon gas.