Characteristics of ALD-TaN thin films using a novel precursors for copper metallization

ALD-TaN thin films derived from tert-buthylimidotrisdiethyl- amidotantalum (TBTDET) and tert-amylimidotrisdim- ethylamidotantalum (TAIMATA) precursors for the diffusion barrier in Cu interconnects were developed. The deposition rate of the ALD-TaN process was saturated at 0.4Angstrom/cycle in a temperature range between 200degreesC and 250degreesC with TBTDET and at 0.2Angstrom/cycle in a temperature range between 150degreesC and 200degreesC with TAIMATA. Both precursors provided roughly comparable film properties such as not only excellent conformality but also composition and structure characterized by XPS and XRD, respectively. ALD-TaN films obtained from above precursors yield low via resistance in aluminum interconnects. However, relatively high via resistance was resulted upon Cu integration as compared to PVD-TaN and Al metallization. The superior diffusion barrier characteristic on Cu metallization was observed with ALD-TaN by BTS result in comparison to the conventional PVD-TaN.