Investigations on ultraprecision machining-induced subsurface damages in silicon

Abstract

Single-crystal silicon used in infrared optics and semiconductor-based products can be machined in a ductile regime to generate crack-free surfaces. However, the subsurface layer partially transforms to the amorphous state. In this work, the amorphous layer formed on Si (001) by plunge-cuts with a round-nosed diamond tool was measured quantitatively by laser micro-Raman spectroscopy. The extent of amorphization depends on the depth of cut ,the tool rake angle and the crystal orientation. It was found that the phase transformation is significant under the cutting conditions where the cutting force becomes larger. Therefore, phase transition is related to the pressure between the tool and the silicon.