THE EFFECTS OF INITIAL GROWTH-CONDITIONS ON THE STRESS PROFILES OF MO SPUTTERED ONTO BOTH MOVING AND STATIONARY SUBSTRATES

In order to understand the influence of the initial growth conditions on stresses in films deposited on scanning substrates, we have made in situ measurements of the stress profiles of Mo sputtered onto stationary and moving glass beams under a variety of conditions. Stationary coatings made directly above the center of the target had stresses ranging from - 1.33 GPa at 2.5 mTorr to + 1.81 GPa at 10 mTorr. At 2.5 and 5.0 mTorr, films deposited on substrates at rest near the edge of the coating zone were considerably more tensile than films grown directly above the target, while films on scanned substrates were only slightly more tensile than those deposited above the target. At 10 and 15 mTorr, films grown under all three conditions had almost the same high level of tensile stress. Coatings were also made directly above the target at 2.5 mTorr onto tensile films with thicknesses which were varied. A 24 nm thick underlayer had little effect on the stress of the subsequent coating, but deposition on top of a 135 nm thick tensile film produced a stress profile which initially followed that of the underlayer, became compressive, and reached a value of - 0.64 GPa after 100 nm of additional growth. We conclude that sufficiently thick high-angle initial growth can affect the stress profile of subsequently deposited material. However, in web or palletized coatings where only a small amount of material is deposited at high angles, the influence is small.