Dry Etching of Ta-Si-N Diffusion Barrier Material in Cf4+02 Gas Mixtures

Abstract

ABSTRACTSputtered Ta36Si14N50 amorphous diffusion barrier layers were reactive ion etched in CF4+02 plasmas. Etch rate varied with gas composition, with 15 percent 02 concentration producing maximum etch rate. Etch rates increased with both pressure and power. Etching proceeded only after an initial delay time which was dependent upon gas composition and applied power. The delay time was probably caused by the presence of a surface native oxide which must first be removed before etching can commence. Auger electron spectroscopy measurements showed the native oxide to be approximately 2 nm thick on as-grown samples, and indicate that near-surface stoichiometry is maintained on etched samples.