Visco‐elastic properties of thin films probed with a quartz crystal resonator

We report on the visco‐elastic characterization of thin layers using a quartz crystal resonator. A parallel ellipsometric setup is used to determine optical thicknesses. A theory of thickness shear resonators covered with visco‐elastic films is presented. The glass transition of a 350 nm film of low‐molecular‐weight polystyrene can be followed. Secondary resonances in frequency shift and damping are observed, when the wavelength of transverse sound is in the same order of magnitude as its thickness. The UV‐induced desorption of poly[(bis)‐m‐butoxy‐phenyl‐silane] shows strong visco‐elastic effects, if done under oxygen atmosphere. Desorption via an oily phase consisting of medium‐size oligomers is suggested. Copyright © 1991 Hüthig & Wepf Verlag