Fabrication of Porous Silicon Microstructures using Electrochemical Etching

Abstract

In this work an equipment was built and tested for the electrochemical etching of silicon in hydrofluoric acid electrolyte using aluminium anode and stainless steel cathode. Porous silicon layer was fabricated in n-type (100) oriented silicon using solution HF : H2O : C2H5OH, 2 : 1 : 1 by volume. It was revealed, that current density determines geometry of the pores and etching anisotropy. Average depth of the obtained pores varied from 16 μm to 27 μm, when width of the pores varied from 2 μm to 5 μm. The depth of pores depended slightly on the current density, and anisotropy was high in the case of small diameter of the pores.