Fabrication of ordered nanostructure on silicon substrate using localized anodization and chemical etching

Nanofabrication processes of Si substrates based on localized anodization and subsequent chemical etching were investigated. The anodization procedure of aluminum sputtered on a Si substrate was monitored by measuring the current transient at a constant voltage. The porous alumina with a self-ordered configuration acted as a mask for the localized anodization of the underlying Si substrate and controlled the position of the silicon oxide pattern, which was produced only in the Al2O3/Si interface. The transfer of the geometric pattern of anodic porous alumina into a Si substrate could be achieved by two independent processes: i) the hole array structure can be obtained by the selective removal of silicon oxide from the Si substrate using wet etching in HIT solution: and ii) the column array structure can be obtained by the selective etching of Si substrate in KOH solution using silicon oxide as a mask. Based on this approach, the different nanostructures could be obtained arbitrarily by the selection of appropriate local anodization stages and etching conditions.