Control the Composition of Tantalum Oxynitride Films by Sputtering a Tantalum Target in Ar/O sub(2)/N sub(2) Radiofrequency Magnetron Plasmas

Tantalum oxynitride films can be deposited with a high versatility in composition by reactive sputtering of a tantalum target in Ar/O sub(2)/N sub(2) mixtures. In this paper, plasma analysis was performed from simple to more complex Ar/O sub(2)/N sub(2) gas mixtures and linked to the layer elemental composition. The presence of two reactive gases accelerates the appearance of Compound Sputtering Mode and modifies the nature of target surface. Hence, in Ar/O sub(2)/N sub(2), nitrogen addition can lead to poison the target surface by a nitride but also by an oxide or by an oxynitride. Finally, this comprehension of interaction between target and reactive gas was used to select suitable flow rate conditions allowing tantalum oxynitride deposition with varying optical properties.[Imageomitted] Sputtering an elemental target with two reactive gases is far from simple. However this paper describes a progressive plasma analysis of various Ar/O sub(2)/N sub(2) atmospheres from simple to more complex gas mixtures. This study shows it is the possible to map the nature of target surface depending on gas flow rates and to correlate it to the composition of deposited films. Hence, tantalum oxynitride films with composition varying from nitride to oxide one can be obtained.