Structural and optical properties of silver thin films deposited by RF magnetron sputtering

Abstract

In this work, we investigate the optical and the structural properties of Ag films by means of spectrophotometric techniques and X-ray diffraction methods in the low- and high-angle regimes. The coatings were grown by radio frequency magnetron sputtering on (100)-oriented silicon substrates. Several sets of samples were produced by varying the sputtering pressure (0.15–0.9 Pa) and changing the sputtering power supply in the range of 25–100 W. In particular, the dependence of the coating optical features, surface roughness, texture and residual stress on the parameter β, proportional to the momentum transferred to the growing film from the energetic particles bombarding it, was pointed out. The results indicate that the Ag films are polycrystalline with a moderate [111] texture and compressive in-plane stress was measured for all the investigated samples. The behavior of the stress with the momentum parameter can be summarized as follows: (i) the compressive stress increases in the range 0<β<300 V 2s/Å; (ii) at β∼400 V 2s/Å it shows a very pronounced maximum; (iii) in the range 400<β<800 V 2s/Å it decreases until reaching a saturation value for β>1000 V 2s/Å.