The effects of collimation on intrinsic stress in sputter-deposited metallic thin films

Abstract An experimental study is presented on the effects of collimation on intrinsic stress in sputter-deposited titanium thin films. A stainless steel square grid collimator with an aspect ration of 1.0 was used, with a collimator wall spacing of 0.5 cm. Thin titanium films were deposited at 0.26, 0.53, 0.80, 1.07 and 1.33 Pa (2, 4, 6, 8 and 10 m Torr) pressure with and without collimation under otherwise identical deposition conditions. The Monte Carlo simulation software package simspud was used in order to simulate some of the changes caused by the introduction of the collimator into the vacuum chamber. The overall level of the intrinsic stress was measured for each deposited film. Films deposited with a collimator consistently exhibited an increased level of accumulated compressive stress when compared with the films deposited by conventional (uncollimated) sputtering. This feature of collimated sputtering may be employed to tailor the stress level in thin film coatings.