Evaluation of surface and subsurface cracks on nano-scale machined brittle materials by scanning force microscope and scanning laser microscope

Nano-scale machining by ultra precision grinding and cutting, known as ductile mode machining, has the potential of overcoming limitations of conventional machining technology. In this study, the nano-scale layers of single crystal silicon and glass surface were machined by a sharply pointed diamond tool, and the subsurface cracks as well as the surface cracks were observed by a scanning force microscope and a scanning laser microscope. The transition point determined by the subsurface cracks is found to be shallower than that by the surface cracks. Therefore the evaluation of the subsurface cracks is important especially in finish machining.