Formation of through-holes on silicon wafer by optical excitation electropolishing method

Through-holes were formed by selective partial electropolishing in a 2.5 wt % HF electrolytic solution, using an N-type, (100)-oriented Si wafer as an anode, and a Pt plate as a cathode. The obtained holes were square through- holes of 5-35 mu m side length, with an aspect ratio of 109. It was possibl e to form such through-holes with a density of 3,500 holes/mm(2) in specifi ed areas. It was also confirmed that the pit of the square-based inverted p yramid structure could form deep capillaries. This suggests the possibility of forming microstructures such as pillars and tubes.