Internal stresses in titanium, nickel, molybdenum, and tantalum films deposited by cylindrical magnetron sputtering

Abstract
Measurements of internal stresses in thin sputtered films of Ti, Ni, Mo, and Ta confirm the onset of compression at low working pressures, as reported earlier for Cr [D. W. Hoffman and J. A. Thornton (in press) Thin Solid Films (Jan. 1977)]. Deposition from cylindrical magnetron sputtering sources gives access to a wide range of low working gas pressures with minimal substrate heating. The transition to compressive film stress at low sputtering pressures is abrupt, and occurs at threshold pressures that increase markedly with the atomic mass of the coating material. Moreover, the electrical resistivity and optical reflectance exhibit transitions in their sputtering‐pressure dependence that shift to higher pressures for the heavier elements. It appears therefore that the transitions in film stress, resistivity, and reflectance are general phenomena caused by an underlying change in the deposition process. A peening mechanism due to energetic particle bombardment is suggested. Data are presented for Ti, Ni, Mo, and Ta films, up to 0.4 μm thick, sputtered onto glass substates at a nominal deposition rate of 1 nm/s, over the pressure range 0.13–4.0 Pa of argon.