Characteristics of WNxCy films deposited using remote plasma atomic layer deposition with (MeCp)W(CO)2(NO) for Cu diffusion barrier

Abstract

Diffusion barrier characteristics of tungsten–nitride–carbide (WNxCy) thin films interposed between Cu and SiO2 layers were studied. The WNxCy films were deposited by remote plasma atomic layer deposition (RPALD) using a metal organic source, (MeCp)W(CO)2(NO), and ammonia. Auger electron spectroscopy analysis indicated the WNxCy films consisted of tungsten, nitrogen, carbon, and oxygen. X-ray diffraction (XRD) analysis showed that the film deposited at 350 °C was nanocrystalline. The resistivity of WNxCy film deposited by RPALD was very low compared to that in previous research because of the lower nitrogen content and different crystal structures of the WNxCy. To verify the diffusion barrier characteristics of the WNxCy film, Cu films were deposited by physical vapor deposition after WNxCy film was formed by RPALD on Si substrate. The Cu/WNxCy/Si film stack was annealed in a vacuum by rapid thermal annealing at 500 °C. Cu diffusion through the barrier layer was verified by XRD. Stable film properties were observed up to 500 °C, confirming that WNxCy film is suitable as a Cu diffusion barrier in microelectronic circuits.