Deposition of Tantalum, Tantalum Oxide, and Tantalum Nitride with Controlled Electrical Characteristics

摘要

Results are presented which indicate that the effects of sputtering voltage and current on the resistivity of films sputtered from pure tantalum appear to be traceable to the pressures and growth rates associated with each sputtering condition. From these data it can be deduced that the observed resistance variations are largely accountable in terms of film impurity content. Tantalum sputtered reactively in the presence of oxygen produces films which are shown to exhibit a sharp transition from relatively low to very high resistivities as the oxygen concentration in the working gas is raised. Changes of greater than 12 orders of magnitude are observed. It is demonstrated that sputtering voltages and anode potentials effect a significant change in the transition point. Similarly well‐defined results are presented on films reactively sputtered in the presence of N2. The results tend to indicate that the anode potential retards (or enhances) electrostatically both the reactive and nonreactive interaction of tantalum with oxygen or nitrogen at the film surface. Results on the effect of substrate temperature on growth rate demonstrate that in reactive sputtering, the reaction occurs at the substrate surface.