Dynamics of UV degradation of PMPSi in vacuum and in the air using in‐situ ellipsometry

Abstract

We present a comparative study of UV degradation of poly[methyl(phenyl)silane] (PMPSi) thin films on Si substrate in HV and in the air. When exposed to UV light with energies around 3.6 eV, the Si backbone scission occurs. The degradation rate is influenced by the presence of oxygen, which is bonded to the Si atoms following the backbone scission. In our experiments, the samples were placed in an HV chamber and ellipsometric spectra were continuously recorded in the 3.3–5.0 eV range. The combined tungsten (halogen)‐deuterium source ensuring a proper level of light intensity used for both exposition and measurement. During 100 hours exposures at atmospheric pressure, the PMPSi film degraded completely and its optical response did not change further. Degradation of the sample exposed in vacuum (at the pressure of 5 × 10–6 Pa) is slower and stops earlier. Ellipsometric technique allowed us to perform detailed studies of the degradation dynamics. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)