A method includes forming hard mask patterns by depositing a support mask layer, a polycrystalline silicon layer, and a hard mask layer on a substrate and etching the hard mask layer, forming pre-polycrystalline silicon patterns by etching the polycrystalline silicon layer using the hard mask patterns as an etch mask, oxidizing side surfaces of the pre-polycrystalline silicon patterns to form polycrystalline silicon patterns and a silicon oxide layer, forming spacer patterns covering sides of the silicon oxide layer, forming a sacrificial layer on a top surface of the support mask layer to cover the silicon oxide layer and the spacer patterns, etching the sacrificial layer and the silicon oxide layer, forming support mask patterns by etching the support mask layer using the polycrystalline silicon patterns and the spacer patterns as an etch mask, and forming activation pins by etching the substrate using the support mask patterns as an etch mask.