Effect of high-frequency on etching of SiCOH films in CHF3 dual-frequency capacitively coupled plasmas

The effect of high-frequency (HF) frequency on etching characteristics of SiCOH films in a CHF₃ dual-frequency capacitively couple plasma driven by 13.56 MHz/2 MHz, 27.12 MHz/2 MHz or 60 MHz/2 MHz sources was investigated in this work. The surface structure of the films after etching and the CHF₃ discharge plasma were characterized. The increase of HF frequency reduced the critical HF power for the etching, suppressed the C:F deposition at the surface of etched films, and improved the etching of SiCOH films. The improvement of etching was attributed to the increase of ions energy and F concentration at high HF frequency.