QUANTITATIVE CHEMICAL TOPOGRAPHY OF POLYCRYSTALLINE SI ANISOTROPICALLY ETCHED IN CL-2/O-2 HIGH-DENSITY PLASMAS

The spatially resolved surface chemical composition of submicron feature (i.e. patterned photoresist (PR) on polycrystalline Si over SiO2) after etching with high-density, low-pressure helical resonator plasma containing O2 and Cl2 was quantitatively determined using angle-resolved X-ray photoelectron spectroscopy as well as scanning electron microscopy. For pure Cl2 plasma, Cl surface concentration was found to be similar for horizontal and vertical surfaces of the poly-Si and PR. Non-occurrence of sidewall passivation was supported by the presence of only small amount of Si on PR sidewall and C and O on the side of poly-Si. For Cl2/5% O2, a small amount of O was found on the poly-Si trench bottom and considerable amount, although submonolayer, on the poly-Si sidewall. The most dramatic effect brought about by the addition of 10% O2 in Cl2-containing plasma was found to be the formation of a thick SiOxCly layer on the side of PR.