Effect of deposition parameters on optical and mechanical properties of MF- and DC-sputtered Nb2O5 films

Niobium-pentoxide films with thicknesses of 100 nm to 1 mum were deposited by both DC and mid-frequency (MF) magnetron sputtering using a dual magnetr on (TwinMag((R))) configuration. Stress measurements were performed by dete rmining the substrate curvature before and after deposition for various pro cess parameters. By varying the argon or oxygen partial pressure, it could be shown that a minimization of the undesired compressive stress, caused by the particle bombardment, is attainable. It was found that the limits for achieving this strongly depend on the applied process (MF or DC) as well as on the target state (oxide or transition mode). The films were characteriz ed using SEM, AFM, vibrating reed, EPMA, and XRD yielding information conce rning morphology, stoichiometry, phase, and surface roughness. Furthermore, ellipsometric measurements allowed the determination of the film thickness es and the refractive indices (n(550 nm) = 2.4) which turned out to be high ly correlated to the stress values. (C) 2001 Elsevier Science B.V. All righ ts reserved.