Using a new wet process based on a catalytic reaction, pores and grooves were formed in Si using Au, Pt, or Ag as the catalyst. The diameter of the pore can be as small as 50 nm. However, to produce wiring in Si wafers, we primarily formed pores with a diameter of about 5 μm. These pores were filled with Cu by electrochemical plating, forming Cu wires developed to the wafer surface. In the process, the catalyst particles remaining at the bottom of the pore acted as seeds for the deposition of Cu and helped fill the pores without the formation of voids. In order to control the position of pores and grooves formed in Si, methods using catalytic electrodes were also developed.