Fabrication of P(100) silicon macro-pore and pillar array by wet electrochemical etching

Abstract

In this paper, pyramidal notch array was pre-etched on P(100) silicon wafer using anisotropic wet chemical etching, then macro-pore/pillar array were successfully processed in the pyramidal notch array by an anodic electrochemical etching. The formation mechanism of macro-pore and pillar in pyramidal notch were investigated, it indicates that the silicon dissolution rate is proportional to electric field, while electric field is mainly concentrated on the tip, edges and corners of the pyramidal notch. Therefore, there is an etching rate difference between the notch corner and planar regions in the pyramid notch. The notch corners are preferentially etched at first, then a pore is formed in the notch. If the shape of the open window is truncated and the bottom size is large enough, four pores would initiate at the notch angels due to etching rate difference between the truncated pyramidal notch corner and notch center, consequently, a pillar is formed in the notch center.