New UHV dilatometer for precise measurement of internal stresses in thin binary-alloy films from 20 to 750 K

Abstract

We describe a new dilatometric device for internal stress measurements of thin binary-alloy films, able to operate in ultrahigh vacuum in the temperature range 20–750 K. Using a three-terminal capacitor method, the displacement of the free end of a thin cantilever substrate is monitored by the capacitance change. With a sensitivity of 1 nm for substrate displacements, the resolution for stress detection is 105 Pa in a 100-nm-thick film. Simultaneously with the stress measurement, the electrical resistivity of the film can be determined on the same substrate. The direct comparison of electrical and mechanical thin-film properties gives the ability to obtain additional information on the growth process and on the thin-film structure. Measurements of a crystalline Cu film and an amorphous Zr20 Co80 alloy film are shown.