Thin films of Cu and Cu on Ti were prepared by sputtering films onto SiO2 substrates. The films were annealed at temperatures between 350 and 400°C in vacuum and hydrogen ambiente. The stress was measured in-situ during the anneals. The stress in vacuum initially was compressive, then became tensile and remained so. The stress in hydrogen started in compression and remained so throughout the anneal. The origin of these stresses is explained as a result of compound formation. In vacuum anneals, TiCu forms during the compressive stage with an activation energy of 1.7 eV, then TiCu3 forms during the tensile stage with an activation energy of 2.5 eV. In hydrogen, a single compound, TiH2, forms under the Cu with an activation energy of 0.93 eV.
Studies on the Cu films indicate that hydrogen reduces the incremental stress formed in the films during annealing. A possible explanation is presented for the stress change in that hydrogen has been shown to assist in annealing dislocations. Experimental evidence of an instantaneous change in the stress state upon the introduction of a new ambient is also presented.