TEMPERATURE-DEPENDENCE OF THE REACTIVITY OF OH(X(2)PI) WITH OXIDIZED SILICON-NITRIDE AND PMMA FILM SURFACES

The reactivity of OH(X2PI) with the surface of both an oxidized silico n nitride film and a poly(methyl methacrylate) (PMMA) film is measured to be 0.60 +/- 0.05 at room temperature. The reactivity of OH with ox idized Si3N4 substrates displays an inverse dependence on substrate te mperature, decreasing to approximately 0 at temperatures above 500 K. The reactivity is determined directly using spatially resolved laser-i nduced fluorescence of OH in a plasma-generated molecular beam inciden t on the surface. The desorbed OH has a cosine angular distribution. N o evidence for a dependence of reactivity on rotational state of the O H was observed. The reactivity of OH with a PMMA film is also explored using different gas compositions in the plasma beam source. Exposure of the PMMA surface to O2 and O2/CF4 plasmas results in the generation and desorption of OH.