Investigation of nanostructure on silicon by electrochemical etching

Fabrication of deep pores and trenches in nano-size will enable the embedded nanodevice integrated with silicon IC. However, the conventional dry etching method needs very expensive equipment and the process is quite complicated. Recently, electrochemical etching was developed to fabricate structures with high aspect ratio. Anodization was performed in a solution of HF with certain concentration mixed with ethanol by 1:1 in volume. The backside of the wafer was illuminated by a halogen lamp. The whole etching system was monitored by a computer system. It is found, in case of etching in a low current with 5%HF electrolyte, the size etched pores can be less than 100 nm. However, the deep trench structures becomes a line array of pores. Further work is in progress to investigate the detail.