Hot-wire-assisted atomic layer deposition of a high quality cobalt film using cobaltocene: Elementary reaction analysis on NHx radical formation

Hot-wire-assisted atomic layer deposition (HW-ALD) has been identified as a successful method to form high quality metallic films using metallocene and NH3. A cobalt film formed by HW-ALD using cobaltocene and NH3 was successfully demonstrated. The authors have elucidated the mechanism of HW-ALD during the precursor feed period and the reducing period. In the case of cobalt, a deposition temperature above 300 degrees C is needed to avoid an inclusion of carbon impurities. This is because the physisorbed species are involved during the precursor feed period. NH2 radical promotes the dissociation of the carbon-metal bond during the reducing period. This is examined by elucidation of the gas-phase kinetics, estimation of the surface reactions by quantum chemical calculations, and analysis of the exhaust gas using a quadrupole mass spectrometer. (C) 2012 American Vacuum Society. [DOI: 10.1116/1.3666034]