Tantalum carbonitride (TaCN) thin films were deposited on SiO2 surface with plasma enhanced atomic layer deposition (PEALD) and thermal atomic layer deposition using tert-butylimido[tri-diethylamido]tantalum (TBTDET) and ammonia. It was confirmed that the film was a mixture of TaC, TaN, Ta3N5, and Ta2O5 with oxide phase formed from the postdeposition uptake of oxygen from the air. It was shown that electrical properties of TaCN film were affected by the atomic composition and phase composition in the film. Effect of the process parameters, such as deposition temperature and plasma power on film composition and electronic properties was studied. Formation of carbide phase was suppressed in the TaCN film deposited with ammonia. As the deposition temperature was increased, the carbide phase and TaN phase in the film were increased, Ta3N5 phase in the film was decreased and the film resistivity was decreased. The uptake of oxygen after deposition was about 5 atom % with the PEALD process and about 30 atom % with thermal ALD process and it is believed that denser film could be obtained with plasma. The resistivity of TaCN film deposited at 350 degrees C and 150 W using PEALD process was about 6.75x10(4) mu Omega cm. (C) 2008 The Electrochemical Society.