INTERNAL-STRESSES IN METALLIC-FILMS DEPOSITED BY CYLINDRICAL MAGNETRON SPUTTERING

Previous studies of the internal stresses in thin films deposited at low T Tm using cylindrical post-cathode magnetron sputtering sources have identifieda transition working pressure for each coating material, below which the internal film stresses are compressive and above which they are tensile. New stress versus working pressure measurements for gadolinium, rhodium, chromium and three nickel-based alloys substantiate the generality of the stress-pressure dependence. The occurrence of compressive stresses correlates with the presence of entrapped argon in the deposits; however, the estimated magnitudes of the corresponding compressive strains remain invariant over large changes in the argon content. It is concluded that the mere presence of argon in the films does not cause compression. When materials sputtered from both post-cathode and hollow-cathode magnetron sources were deposited onto specially shielded substrates, large compressive stresses occurred only where geometric factors indicated enhanced bombardment by energetic argon reflected from the cathode. Atomic peening (forward sputtering and recoil damage to the depositing films) is suggested as a cause of the compressive stresses in the films sputtered at low working pressures. © 1979.