Stress in Co-Ni-Fe and Ni-Fe Films

Abstract

The stress measured at 25°C in vapor‐deposited Co‐Ni‐Fe and Ni‐Fe films was investigated as a function of composition, grain size, substrate temperature, film thickness, and annealing parameters. The stress was determined by measuring the change in curvature of circular substrates with an interferometer. Various compositions were studied. The ranges of each constituent were 0%–50% Co, 50%–90% Ni, and 10%–50% Fe. A dependence of stress on composition existed even when the substrate temperature and grain size remained constant. The residual stress has a nearly parabolic dependence on substrate deposition temperature with a minimum in the vicinity of 275°C. This is in general agreement with the results for Ni‐Fe films using different techniques and previously reported by Weiss and Smith. The stress is nearly constant for film thicknesses 1000–10 000 Å and can be reduced by annealing, provided the annealing temperature is greater than the temperature of deposition.