The physical properties of cubic plasma-enhanced atomic layer deposition TaN films

Abstract

Plasma-enhanced atomic layer deposition (PE–ALD) is a promising technique to produce high quality metal and nitride thin films at low growth temperature. In this study, very thin (<10 nm) low resistivity (350 μΩ cm) cubic TaN Cu diffusion barrier were deposited by PE–ALD from TaCl5 and a plasma of both hydrogen and nitrogen. The physical properties of TaN thin films including microstructure, conformality, roughness, and thermal stability were investigated by various analytical techniques including x-ray diffraction, medium energy ion scattering, and transmission electron microscopy. The Cu diffusion barrier properties of PE–ALD TaN thin films were studied using synchrotron x-ray diffraction, optical scattering, and sheet resistance measurements during thermal annealing of the test structures. The barrier failure temperatures were obtained as a function of film thickness and compared with those of PE–ALD Ta, physical vapor deposition (PVD) Ta, and PVD TaN. A diffusion kinetics analysis showed that the microstructure of the barrier materials is one of the most critical factors for Cu diffusion barrier performance.