Comparison of the structure and electrical properties of thin tungsten films deposited by radio frequency sputtering and ion beam sputtering

Thin films of tungsten have been prepared by radio frequency (rf) diode sputtering and a saddle field ion beam source. The microstructure and electrical properties of the ion-beam sputtered films are comparable to those of rf sputtered films deposited at low-deposition rates. rf sputtered films deposited at high rates have larger grains and consist of β-W. They also have lower sheet resistances. An x-ray photoelectron spectroscopy analysis revealed that all of these films contained a considerable proportion of oxygen, the ion beam sputtered films containing more. Ion beam sputtering offers no advantages over low-rate rf sputtering of tungsten.