A doped mold film is formed with a dopant concentration gradient in the doped mold film that continuously varies in a thickness direction and a portion of the doped mold film is etched in the thickness direction to form a hole so that an electrode can be formed along an inner wall of the hole. The electrode thus formed includes a first outer wall surface, a second outer wall surface, and a third outer wall surface wherein the first outer wall surface is in contact with a sidewall of an insulating pattern formed on a substrate within a through hole formed in the insulating pattern; the second outer wall surface is in contact with a top surface of the insulating pattern and extends in a lateral direction; the third outer wall surface is spaced apart from the first outer wall surface with the second outer wall surface therebetween; and the third outer wall surface extends on the insulating pattern in a direction away from the substrate.