Chemical vapor deposition growth and properties of TaCxNy

TaCxNy films were characterized and evaluated for suitability as copper diffusion barriers for advanced interconnect structures. Films were deposited from pentakis(dimethylamino)tantalum, Ta[N(CH3)2]5, and methane by thermal chemical vapor deposition (CVD) at 365 deg. C and plasma enhanced CVD (PECVD) at 185-245 deg. C. Film composition was characterized using in situ X-ray photoelectron spectroscopy. Electrical resistivities of 6320-19600 μΩ·cm were measured for thermal CVD films and 440-2360 μΩ·cm for PECVD films. Furthermore, PECVD films contained TaC crystallites, and surface roughness decreased from 1.98 to 1.26 nm with increasing temperature. Copper diffusion barrier effectiveness was evaluated for blanket film structures with copper and barrier films deposited in situ on SiO2. Secondary ion mass spectrometry depth profiling of annealed samples (8 h at 360 deg. C) with barrier thickness ranging from 4 to 10 nm indicated the barrier prevented copper diffusion to SiO2