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

We have proposed a novel etching gas C
₅
F
₁₀
O 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 C
₅
F
₁₀
O gas produced many CF
₃

⁺
ions which have a large etching yield due to its special molecular structure and the deposition of polymers was decreased by addition of the N
₂
gas. Consequentially, the Ar/C
₅
F
₁₀
O/N
₂
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/C
₄
F
₈
/N
₂
plasmas.