Effect of low-frequency power on etching of SiCOH low-k films in CHF3 13.56 MHz/2 MHz dual-frequency capacitively coupled plasma

This work investigates the etching characteristics of SiCOH low dielectric constant (low-k) films in the CHF3 13.56 MHz/2 MHz dual-frequency capacitively couple plasma (CCP). The effect of low-frequency (LF) power on etching behavior is analyzed. The results show that the increase of LF power can leads to a transition of etching behavior from films deposition to etching. By Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) analysis on the etched SiCOH films and optical emission spectroscopy (OES) analysis on the plasma radicals, the transition behavior is found to relate to the suppression of C:F deposition due to the energetic ions sputtering and the increase of F concentration at higher LF power.