Oxygen content dependent etch rate of single polymer microparticles confined in the sheath region of a low pressure radiofrequency argon/oxygen plasma

Abstract

\u3cp\u3eTo study the etching of polymer microparticles confined in low pressure radiofrequency plasmas, the size and refractive index of single 2 μm particles are experimentally obtained as a function of both time and oxygen content (0%-50%) added to the argon background gas. The etch rate was found to depend heavily on the oxygen (O\u3csub\u3e2\u3c/sub\u3e) content, especially for mixtures with low fractions of O\u3csub\u3e2\u3c/sub\u3e. As expected the etch rate was found to be close to zero in absence of O\u3csub\u3e2\u3c/sub\u3e and increases to a value of 2 nm min\u3csup\u3e-1\u3c/sup\u3e for 0.5% O\u3csub\u3e2\u3c/sub\u3e and to roughly 3.5 nm min\u3csup\u3e-1\u3c/sup\u3e for 5% O\u3csub\u3e2\u3c/sub\u3e. Above 5% O\u3csub\u3e2\u3c/sub\u3e the etch rate saturates. It is shown that these results are consistent with a steady state etch model taking the effects of both atomic oxygen and positive ions into account.\u3c/p\u3