Evolution of the mechanical properties of a femtosecond laser modified layer onto a silicon wafer

Abstract

Femtosecond laser marking was performed on a silicon single crystal. The mechanical properties were studied by using nanoindentation and Atomic Force Microscope (AFM) techniques. This work shows that the femtosecond laser irradiation of the material involves mechanical modifications of the surface layer. The more the quantity of photonic energy is deposited, the more important the modifications. AFM technique, coupled with nanoindentation technique, prove that the femtosecond laser modified layer is softer and less brittle compared to the as-received silicon wafer. A discussion concerning the coupling between roughness and measurements with nanoindentation is proposed. Under these assumptions, estimations of the deepness of the modified layer are given.