Surface finish improvement of an unpolished silicon wafer using micro-laser assisted machining

Abstract

In this research single point diamond turning (SPDT) is coupled with the micro-laser assisted machining (µ-LAM) technique to machine an unpolished single crystal silicon (100) wafer. SPDT of silicon (Si) can be an extremely abrasive process due to the hardness of this material. Manufacturing this material without causing surface and subsurface damage is extremely challenging due to its high hardness, brittle characteristics and poor machinability. However, ductile regime machining of Si is possible due to the high pressure phase transformation (HPPT) occurring in the material caused by the high compressive and shear stresses induced by a single point diamond tooltip. The µ-LAM system is used to preferentially heat and thermally soften the workpiece material in contact with the diamond cutting tool. Different outputs such as surface roughness (Ra, Rz) and depth of cut (DoC) for different sets of experiments with and without the laser were compared and analysed.