Femtosecond Laser Patterning and Anisotropic Wet Etching of Silicon Wafer for Fabrication of Periodic Structures

Abstract

Laser surface modification of Si wafer is a well-known method in the semiconductor industry. It has been repoted that scratching of the surface by an AFM probe induces surface phase transition on silicon (Si) wafer. This can act as an etching mask against potassium hydroxide (KOH) solution. In this study, a combination of formation of laser-induced surface periodic structure by low fluence femtosecond laser irradiation on crystalline Si wafer and anisotropic wet etching achieved the formation of the structures with different morphology from the conventional. Femtosecond laser pulses (800nm, 120fs) were irradiated on the surface of Si (110) in order to form periodic structures with the lowest fluence possible. After the structures formation, anisotropic wet etching by KOH solution was performed. The structures played as an etching mask to form the periodic structures with the aspect ratio more than 0.6 and the separation about the irradiated wavelength.