providing a wafer including a first face, a second face, a plurality of integrated circuit (IC) chips having chip pads on the first face, and scribe lanes running between the IC chips;

forming holes in the first face of the wafer such that the holes respectively penetrate through the chip pads;

forming a base metal layer on the first face of the wafer such that the base metal layer covers inner surfaces of the holes;

forming electrode metal layers respectively on the chip pads such that the electrode metal layers respectively fill the holes;

grinding the second face of the wafer such that the electrode metal layers are exposed through the second face of the wafer;

after grinding the second face of the wafer, attaching a temporary buffer tape to the base metal layer on the first face of the wafer;

forming plated bumps respectively on the electrode metal layers exposed through the second face of the wafer;

removing the temporary buffer tape from the first face of the wafer;

selectively removing the base metal layer located between the electrode metal layers after removing the temporary buffer tape; and

separating the wafer along the scribe lanes.