Abstract
The effect of irradiating EMIM+ or N(CN)2- ion beams by using an ionic liquid ion source was discussed for application to metal-free negative-ion focused ion beams. We found that N(CN)2- ion beams exhibit substrate etching under an acceleration voltage greater than 1 kV. Especially, N(CN)2- irradiation at 4 kV yields large etching depth in Si substrates, as estimated by a Si/N(CN)2- sputtering yield of 10.0, and causes surface smoothing due to chemical etching, which was indicated by a decrease in the surface roughness of Si from 0.07 nm to 0.05 nm. In contrast, glass substrates were mainly etched with physical sputtering by incident ion beams. Moreover, the results of XPS and spectrophotometer measurements revealed that the irradiation of N(CN)2- at 1 kV forms a carbon-nitride film including g-C3N4.
