Internal stresses in amorphous silicon films depositied by cylindrical magnetron sputtering using Ne, Ar, Kr, Xe, and Ar+H2

Abstract

Previous investigations of the thin metal films deposited using cylindrical-post magnetron sputtering sources have identified working gas transition pressures below which the internal stresses are compressive and above which they are tensile. The transition pressures increase with the atomic mass of the target material (Mt) relative to that of the working gas (Mg). This paper reports the occurrence of stress transitions in amorphous silicon films formed by dc cylindrical magnetron sputtering from a P-doped Si target using Ne, Ar, Kr, Xe, and Ar+H2 as working gases. The compressive stresses were comparable to those seen in metal films (∠1 GN/m2). However, the transition pressures and entrapped gas contents were greater than for metal films with comparable Mt/Mg. Experiments with special shields were conducted to investigate the mechanism of gas entrapment. The occurrence of large compressive stresses and entrapped gas concentrations for films such as these, where Mt/Mg<1, suggests that mechanisms different from simple target ion reflection, proposed in the earlier metallic film studies, are operative.