Environmental-Friendship Etching Process of Low-k SiOCH Films Employing an Alternative Fluorocarbon Gas

We have proposed a novel etching gas C₅F₁₀O of which global warming potential would be less than 50, for the plasma etching of SiOCH. The etching was performed using a dual frequency capacitively coupled plasma (CCP). The high performances of a high etching rate and a high selectivity over resist films were obtained. The C₅F₁₀O gas produced many CF₃ ⁺ ions which have a large etching yield due to its special molecular structure and the deposition of polymers was decreased by addition of the N₂ gas. Consequentially, the Ar/C₅F₁₀O/N₂ plasmas have a great potential for realizing a higher etch rate of 980 nm/min and a high etching selectivity over resist of about 7 than the Ar/C₄F₈/N₂ plasmas.