There is provided a method for performing a pre-treatment to form a copper wiring in a recess formed in a substrate, which includes forming a barrier layer on a surface of the substrate that defines the recess, and forming a seed layer on the barrier layer. The method further includes at least one of etching the barrier layer and etching the seed layer. In the at least one of etching the barrier layer and etching the seed layer, the substrate is inclined with respect to an irradiation direction of ions while rotating the substrate.