ECR型イオン源を用いた単結晶ダイヤモンドの酸素イオンビーム加工

抄録

Reactive ion beam etching of diamond chips with oxygen ions using a Kaufman-type ion source has been investigated. Instability of thermionic emission and short life span of the thermionic tungsten filament (cathode) in a Kaufman-type ion source become problems, because the thermionic filament is attacked by the reactive oxygen species. Therefore, an electron cyclotron resonance (ECR) -type ion source which has no thermionic filament has been used in the experiment. This paper reports etching characteristics of diamond chips processed with an oxygen ion beam using an ECR-type ion source. The specific etching rate increases with increasing ion energy, and reaches a maximum rate at an ion energy of 300 eV, then decreases gradually with further increasing ion energy. The specific etching rate processed with 1000 eV oxygen ions increases with increasing ion incident angle and reaches a maximum rate at an ion incident angle of 40°, then decreases with increasing ion incident angle. The specific etching rate processed with 500 eV oxygen ions decreases with increasing ion incident angle. The specific etching rate processed with 500 eV oxygen ions at an ion incident angle of 0° which includes both physical and chemical reactions is 12 times greater than that processed with argon ions which cause only a physical sputtering reaction. Futhermore, the surface roughness of diamond before and after oxygen ion beam etching was evaluated using an atomic force microscope (AFM) and a scanning electron microscope (SEM). It was found that the specific surface roughness increases with increasing ion incident angle, and decreases with increasing ion energy.