CF4/O2 Gas Chemistry에 의해 식각된 Ru 박막의 표면 반응

Abstract

Ru thin films were etched using CF4/O2 plasma in an ICP (inductively coupled plasma etching) system. The maximum etch rate of Ru thin films was 168 nm/min at a CF4/O2 gas mixing ratio of 10 %. The selectivity of SiO2 over Ru was 1.3. From the OES (optical emission spectroscopy) analysis, the optical emission intensity of the O radical had a maximum value at 10 % CF4 gas concentration and decrease with further addition of CF4 gas, but etch slope was enhanced. From XPS (x-ray photoelectron spectroscopy) analysis, the surface of the etched Ru thin film in CF4/O2 chemistry shows Ru-F bonds by the chemical reaction of Ru and F. RuFx compounds were suggested as a surface passivation layer that reduces the chemical reactions between Ru and O radicals. From a FE-SEM (field emission scanning electron microscope) micrograph, we had an almost perpendicular taper angle of 89°.