Study of oxygen addition to CF₃Br reactive ion etching plasmas: Effects on silicon surface chemistry and etching behavior

The etching of silicon in CF3Br/O2 plasmas has been examined. In situ x-ray photoelectron spectroscopy shows that silicon surfaces etched in CF3Br/O2 plasmas with a proportion of 30% O 2 or less are covered with a reaction layer that is mainly due to bromine bonded to silicon. As the proportion of oxygen is increased above 30% the reaction layer becomes thicker and contains mainly fluorine and oxygen, and the silicon etch rate decreases simultaneously.