Thermomechanical strains in small-size Au–GaAs thin film structures

In small-size contact technology, when dielectric covers with opened circular windows are used, the thermal strains appear to be considerable because of the different thermal expansion of the semiconductor GaAs., deposited metal Au.and dielectric cover SiO2., widely used for manufacturing the devices. The strains occurring in the Au layer, in turn, result in defect formation or disappearance. It depends on two contrary processes: i. the Au atom migration from the Au layer on the SiO2 surface to the GaAs windows at temperatures below 4508C; ii. the Ga atom migration from the GaAs windows into the Au on SiO2 at temperatures beyond 4508C. Therefore, these processes ought to be taken into account in the pattern design of ‘‘honey-comb’’ structures: window dimensions, distances between the windows, SiO2 and Au layer thicknesses and their ratio. q2000 Elsevier Science B.V. All rights reserved.