PERSPECTIVE ON STRESSES IN MAGNETRON-SPUTTERED THIN-FILMS

For nearly 10 years, J. A. Thornton and the present author pursued a series of investigations on a curious and initially obscure effect of intrinsic stress reversal in magnetron-sputtered thin films. This study was first undertaken to understand the mechanical failures of decorative chromium when deposited on plastic automotive grilles. The present paper follows the evolution of these investigations in which the more than 1000 samples were mailed in small batches on a round trip between the author's laboratory in the east and Thornton's in the west. As the work developed it became clear that the structure-sensitive stress reversal was a phenomenon of broad generality, which reflected subtle changes in the growth microstructures and accompanying properties of magnetron sputtered films. It was postulated that these changes resulted from particle bombardment fluxes controlled by sputtering process parameters. This review recalls various experiments that were conceived to explore mechanisms and map out the stress reversal locus in parameter space.