The pyrolytic and photolytic conversion of a new polymer precursor, namely -chloroethyl-silsesquioxane (BCESSQ), to an ormosil film is presented. At 350 C the film thickness rapidly decays to 55% of its original thickness within 60 min. A range of ion scattering techniques are used to completely characterize the film stoichiometry. Upon increasing temperature from 225 C to 450 C, the carbon, hydrogen and chlorine atomic concentrations monotonically decrease. Although Cl is completely removed, the C and H concentrations are significant after thermal processing (i.e., 10 at % and 30 at % at 450 C). Nevertheless, the ormosil films are found to have lower C and H concentrations than commercial materials. Using x-ray reflectivity, the film density is measured and found to reach 1.92 g/cm3 at 450 C. AFM and SEM studies show that the surface is smooth, the bulk is void free, and the interface continuous. Upon exposure to ultra-violet-ozone radiation, BSCESSQ films ranging from ca.( 200 to 700) nm are found to convert to ormosil films within ca. 30 mins. Surprisingly, the Cl concentration is found to decrease more quickly than the H and C concentrations, suggesting that the ormosil film evolves HCl initially leaving a vinyl group of Si-CH=CH2. This reaction pathway differs from the thermal case. UV-ozone processed films are found to have much lower C and H concentrations than the pyrolytic films. However, the UV-ozone films have a lower density, for example 1.71 g/cm3 for 24 min exposure.
Citation: Thin Solid Films
Pub Type: Journals
dielectric, ion scattering, ormosil, photolysis, polysilsesquioxane, pyrolysis, silsesquioxane, thin film, ultraviolet irradiation