A system for processing residual gas that includes a chamber having at least one baffle for increasing gas flow path, a residual gas inlet mechanism connected to the chamber for supplying residual gas to the chamber, at least one first gas inlet mechanism connected to the chamber for supplying inert gas to the chamber, at least one second gas inlet mechanism connected to the chamber for supplying a reactive gas to the chamber, and a gas outlet mechanism for connected to the chamber for outputting mixed gases from mixing the residual gas, inert gas and reactive gas and non-reacted residual gas, inert gas and reactive gas.