Cross-section transmission electron microscope observations of diamond-turned single-crystal Si surfaces

Diamond turning was carried out along the [110] direction on the (001) plane of single-crystal silicons at extremely small depths of cut of 100 and 500 nm. Cross-section transmission electron microscope observations revealed that turning had converted the layers of the surface into an amorphous structure directly, as well as in continuous chips. The thickness of the layers was about 150 nm in spite of the depth of cut. Under the amorphous layer, another damaged layer with many dislocations was formed, the thickness of which was about 2 and 3 μm at 100- and 500-nm cutting depth, respectively. At 500-nm cutting depth, microcracks were formed through the accumulation of excessive dislocations. At both depths of cut, however, the dislocations were mostly oriented along the 〈110〉 directions within the {111} planes. It was found that ductile-regime turning could be achieved by amorphization and deformation based on the {111}〈110〉 slip systems.