C₄F₆ Etching Characteristics for High‐Aspect‐Ratio Etching of SiO₂ Films Using an Inductively Coupled Plasma Etching System With Low‐Frequency Bias Power

ABSTRACT In this study, the etching characteristics of C 4 F 6 gas are investigated using inductively coupled plasma (ICP) etching equipment to apply a high‐aspect‐ratio etching process to SiO 2 . The use of a CF 4 + C 4 F 6 + He gas mixture in the ICP etching system provides a lower F atom density, a higher polymerization capacity with increasing C 4 F 6 gas proportion, and better SiO 2 /amorphous carbon layer selectivity. With an increase in the C 4 F 6 gas mixing ratio, the bowing phenomenon is alleviated, and a vertically etched profile is formed regardless of the source and bias power. The etching characteristics demonstrate that ICP etching using C 4 F 6 gas is an excellent alternative to capacitively coupled plasma (CCP) etching for the development of next‐generation high‐aspect‐ratio‐contact etching processes.