プラズマCVM (Chemical Vaporization Machining) による超精密加工

抄録

A novel chemical machining method using neutral radicals generated by atmospheric-pressure plasma, which we call “chemical vaporization machining” (CVM), has been developed to overcome the problem of deformed layers in conventional mechanical machining processes (turning, grinding, lapping, etc.). By use of a high-speed rotary electrode to generate the plasma we achieved a high machining efficiency equivalent to that of mechanical machining. Since the generated plasma is localized around the electrode due to the high-pressure atmosphere, the spatial resolution is good. The defect density of the machined surface is very low and is equivalent to that of chemical etching. A numerically controlled plasma CVM machine was developed for fabricating ultra-high-accuracy optical elements and semiconductor substrates. Gas bearings are used for the rotary electrode and xy-table to maintain the cleanliness of the atmosphere. A fabricated X-ray mirror had a flatness of 22.5 nm, and a fabricated silicon-on-insulator had a film thickness of only 13.5 nm.