Process parameter effects on residual stress and phase purity after microlaser-assisted machining of silicon

Machining brittle materials, such as silicon, is expensive and often causes detrimental damage, but a relatively new technique, termed microlaser-assisted machining (micro-LAM), improves the efficacy of the machining process using traditional single point diamond turning with simultaneous laser assistance. Prior work shows it provides a smooth surface finish and reduces the likelihood of fracture by increasing the ductility of the material during the machining process. However, the quality of the finish and the utility of the machined silicon depends on having good phase purity and low residual stresses. Using Raman microspectroscopy and a wide range of micro-LAM machining parameters the current work has shown that the technique can give excellent results in terms of low residual stress, high phase purity, and good relative crystallinity. However, poor choice of process parameters can be very detrimental leading to high residual stresses (over 400?MPa) and multiple silicon phases being present.