Reactive sputter-deposition of oxygenated amorphous carbon thin films in Ar/O2

Oxygenated amorphous carbon thin films were deposited by DC magnetron sputtering using various argon and oxygen process gas mixtures. The X-ray diffraction data indicated that the predominantly amorphous films had more defined peaks with a higher partial pressure of oxygen. Results indicated that use of oxygen in the working gas enhanced the crystalline nature of the films. Scanning electron and atomic force microscopy revealed that the surface roughness and film topography differed with the oxygen process gas variations. X-ray photoelectron spectroscopy revealed increased surface oxygen content with higher oxygen concentration in the working gas. Raman spectroscopy results suggested that the increased oxygen in the films may have led to a higher percentage of sp3-bonded carbon atoms. The growth rate (deposition rate) of the films decreased as the amount of oxygen increased. This decreased deposition rate was associated with an oxygen etching of the film.

Research Highlights
► Oxygenated a-C thin films were sputter-deposited from a graphite target in Ar/O2.
► XRD revealed that the films were amorphous with broad peaks of a nano-crystalline phase.
► SEM results revealed increased surface topography with increased oxygen in the films.
► Raman spectroscopy showed increased oxygen led to a higher percentage of sp3-bonding.
► Increased oxygen content enhanced the long-range order in the films.