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

Anew 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 degrees C in combination with NH3 plasma. The TaN PEALD showed a saturated growth rate of 0.062 nm/cycle and a high film density of 9.1-10.3 g/cm(3) at 200-250 degrees 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 (0-6 nm)/Si stacks at 400-800 degrees C, and excellent Cu diffusion barrier properties were observed even with ultrathin 2 nm-thick TaN film.