Characteristics of PAALD-TaN thin films derived from TAIMATA precursor for copper metallization

PAALD (plasma assisted atomic layer deposition)-TaN thin films derived from a precursor, tert-amylimidotrisdim-ethylamidotantalum (TAIMATA), for the diffusion barrier in Cu interconnects were developed and compared to the thermal ALD-TaN. The deposition rate of the PAALD-TaN process was around ∼0.9 Å/cycle at 250 °C. The resistivity of TaN film by the PAALD was ∼ 366 μohm-cm, while the resistivity by the thermal ALD was not measurable. The PAALD-TaN and thermal ALD-TaN film appeared to have cubic and amorphous phase, respectively. In Cu metallization, as TaN thickness increased, via resistance with thermal ALD-TaN increased dramatically, but via resistance with PAALD-TaN was almost constant and much lower than that with thermal ALD-TaN. Using PAALD-TaN, the diffusion barrier characteristics was also improved in comparison to thermal ALD-TaN.