Characteristics of tantalum oxynitride films prepared by rf magnetron sputtering

Abstract

Tantalum oxynitride (TaOxNy) thin films were prepared in a RF magnetron sputtering system. The film properties with various sputtering parameters such as RF power, gases ratio, and substrate temperatures were investigated. In comparison with tantalum oxide films, the film properties are strongly affected by the nitrogen content. The microstructure studied by XRD and TEM revealed amorphous. When the nitrogen content varied from 20% to 80%, the deposition rates increase from 5.5 to 11.8 nm/min. Because of the stronger affinity of oxygen to Ta than nitrogen does, the oxygen content of the films is always higher than nitrogen content, even if the partial pressure of nitrogen is higher than that of oxygen. The highest refractive index (n) of the tantalum oxynitride film is 2.29 and the extinction coefficient (k) is nearly zero. The refractive index is inversely proportional to the substrate temperature. The mean square surface roughnesses measured by SPM (scanning probe microscopy) for as-deposited at room temperature and 300 degree(s)C were 0.56 nm and 0.17 nm, respectively. By way of a micro-electro-mechanical system (MEMs) technique- the cantilever beam method, the films show a compressive residual-stress state and the coefficient of thermal expansion (CTE) is also measured. The thermal properties were deeply affected by the nitrogen. Thus, TaOxNy films with suitable x,y values are good candidate dielectric materials for optical or magneto- optical purposes.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.