スパッタ加工面特性

Abstract

The ion beam sputter-machining is suitable as a surface finishing process of inorganic materials, and its mechanism is different from the conventional polishing process.The sputter-machining apparatus is constituted in such a way that the gas of ion source is argon and the ion gun is of a duo-plasmatron type which emits the ion beam of 1 mA/cm2 current density at accelerating potential of 20 kV.In the experiment the sputter-machining of BK-7 glass highly polished beforehand was done under the conditions that the ion beam current is 200μA, the incident angle 60°, the rotation speed of workpiece 20 rpm and then the sputtering rate S of 1.2 mol/ion and the machining rate of 14.4A/s in depth were obtained.From the results of experiments the following conclusions were obtained.(1) The machined surface and sputtering rate are largely affected by the incident angle of ion beam. The deteriorated surface appears at an incident angle of 60 degrees.(2) The surface finishing of optical surface can be performed by selecting proper machining conditions for the incident angle, rotation of workpiece and so on.(3) The contamination of workpiece is kept out by the electron neutrizing effect.