Stress relaxation in Al(Cu) thin films

Abstract

Substrate curvature measurements were used to study both the stress changes during thermal cycling and the kinetics of tensile stress relaxation in 800 nm Al (0.5wt% Cu)-films on oxidized Si-substrates. Qualitative microstructural evidence is provided for the observed decrease in room-temperature stress after the first and subsequent thermal cycles. Isothermal relaxation measurements at temperatures up to 100°C could be described well by dislocation glide with an activation energy of 3.0±0.3 eV and an average athermal flow stress of 600±200 MPa. Evidence for an Orowan-strengthening mechanism is provided by TEM-investigation.