Thin aluminum films deposited on silicon substrates are representative of materials systems used in integrated circuit technology. Large stresses in such systems usually arise from thermal expansion mismatch between the thin film and the substrate, and constitute an important reliability concern.
X-ray and continuous indentation testing were used to measure post-heat treatment stresses in a 0.3 μm thick aluminum film on a silicon substrate. The sample was heat treated at 450°C for one hour in an inert atmosphere, after which the stress relaxation was followed as a function of time. The stress data gathered by the two techniques agree very closely during a time span of about 100 hours.