Degradation of poly(methyl methacrylate) in CF4 and CF4/O2 plasmas

The degradation of poly(methyl methacrylate) films exposed to CF4 and CF4/O2 plasmas in a parallel plate reactor is investigated by means of gel permeation chromatography. Profile results indicate that degradation is high in the top few thousand angstroms, although reductions in molecular weight are observed throughout the 1.5 μm films. Oxygen additions to CF4 generate increases in PMMA etch rates, but molecular weight profiles suggest that degradation is still confined to the film surface. The shifts in molecular weight distribution obtained from plasma degradation experiments are simulated by a random scissioning model.