Effect of Cu-Assisted Chemical Etching for Black Silicon

Black silicon is surface modification of silicon like nano-structure, that significantly decreases reflectivity of the silicon wafer surfaces. An effective and economical fabrication process for black silicon is metal-assisted chemical etching (MACE) method. In this paper, Cu particles were deposited using solution of Cu(NO ₃ )2:HF=0.1M:1.8M and wafers were etched by HF/H ₂ O ₂ solution. The reflectance of 5.92% was obtained with etching time of 90 min. This is because the wafer was nonuniformly etched with the increasing of etching time. With the etching time of 5 min, it showed the lowest reflectance of 3.96% because of uniform structure and reduced pore size.