Viscoelastic Behaviour of Oxide Films on Silicon Crystals

The viscoelastic behaviour of oxide films on steam-oxidized silicon crystals is investigated by means of real-time X-ray topographic observations in the temperature range from 300 to 1273 K. The observations are performed on oxide films of various thicknesses grown at 1273 K. The strain contrast along the boundary between the oxidized region and the oxide-removed region decreases with increasing temperature and disappears not only at the oxidation temperature but also at temperatures fairly below the oxidation temperature by a prolonged annealing. The curvature of the oxidized regions is changed during heating–cooling thermal cycles in parallel with the change of strain contrast. This change of contrast due to the thermal cycling is reversible and found to be definitely due to the viscoelastic behaviour of oxide films at high temperatures.