Effects of Oxygen and Nitrogen Atoms on SiOCH Film Etching in Ultrahigh-Frequency Plasma

Behaviors of absolute densities of O and N atoms and their effects on the etching characteristics of SiOCH film were investigated in ultrahigh-frequency (UHF) plasma. O2 or N2 are added into the plasma employing C4F8 diluted with Ar. The absolute densities of O and N atoms were evaluated by vacuum uv absorption spectroscopy, and CFx radical densities by ir diode laser absorption spectroscopy technique. These radical densities were of the order of 1011-1012 cm-3 under typical etching conditions. The effect of the contribution of O atoms in SiOCH film etching was larger by one order of magnitude than that of N atoms. 20 refs.