Growth of tantalum nitride film as a Cu diffusion barrier by plasma-enhanced atomic layer deposition from bis((2-(dimethylamino)ethyl)(methyl)amido)methyl(tert-butylimido)tantalum complex

Abstract

A new bis((2-(dimethylamino)ethyl)(methyl)amido)methyl(tert-butylimido)tantalum complex was synthesized for plasma-enhanced atomic layer deposition (PEALD) of tantalum nitride (TaN) film. Using the synthesized Ta compound, PEALD of TaN was conducted at growth temperatures of 150–250°C in combination with NH3 plasma. The TaN PEALD showed a saturated growth rate of 0.062nm/cycle and a high film density of 9.1–10.3g/cm3 at 200–250°C. Auger depth profiling revealed that the deposited TaN film contained low carbon and oxygen impurity levels of approximately 3–4%. N-rich amorphous TaN films were grown at all growth temperatures and showed highly resistive characteristic. The Cu barrier performance of the TaN film was evaluated by annealing of Cu/TaN (0–6nm)/Si stacks at 400–800°C, and excellent Cu diffusion barrier properties were observed even with ultrathin 2nm-thick TaN film.