Characteristics of tantalum carbo-nitride thin films deposited with atomic layer deposition process

摘要

Tantalum carbo-nitride (TaCN) thin films were deposited on SiO_2 surface with the plasma enhanced atomic layer deposition (PEALD) and thermal atomic layer deposition using tert-butylimido-tris (diethylamido)-tantalum (TBTDET) and reactive gas such as hydrogen and ammonia. It was confirmed that the film was a mixture of TaC, TaN, Ta_3N_5 and Ta_2O_5 with oxide phase formed from the post-deposition uptake of oxygen from the air. It was shown that electrical properties of TaCN film were affected by the phase composition in the film. Effect of the process parameters such as deposition temperature and plasma power was studied and their effect on phase composition and electronic properties was evaluated. With the increase of the carbide phase and TaN phase over Ta_3N_5 phase, the resistivity of the film was decreased. As the deposition temperature was increased, the carbide phase and TaN phase in the film were increased and the film resistivity was decreased. The formation of carbide phase was suppressed in the ammonia ALD process. The uptake of oxygen after deposition was about 10 atomic % with the PEALD process and about 30 atomic % with thermal ALD process and it is believed that denser film could be obtained with plasma.