Novel precision machining using gas cluster ion beams

Novel precision machining using gas cluster ion beams (GCIB) is proposed to fabricate a small lens or free-surface mold. Properties of GCIB such as surface smoothing, high-rate etching and ease of forming a collimated beam are promising for novel precision machining. In this study, GCIB machining of a small mold (0.56 mm in diameter) and a free-surface mold was demonstrated. Before irradiation, a hillock (height 195 nm and width 240 μm) was observed on the center of the mold. By collimated GCIB irradiation with precise ion dose and position controls, the difference between designed and measured shape was decreased from 195 to 26 nm. Also, free-surface mold fabrication was demonstrated using position controlled GCIB. The error of etching depth from the designed shape was 10 nm for free-surface mold.