Tantalum nitride formation by low-energy (0.5-5 keV) nitrogen implantation

The formation of TaNx films by in situ nitrogen implantation with energies from 0.5 to 5 keV has been investigated in a wide compositional range (0 less than or equal to x less than or equal to 0.92). X-ray photoelectron spectroscopy (XPS) and valence band x-ray photoelectron spectroscopy (VBXPS) have been used to characterize the chemical composition and electronic structure of the films, The XPS results show that nitrogen composition is dependent on both the ion dose and ion energy. For a given energy the nitrogen composition increases with increasing ion dose. The composition range obtained is consistent with a transformation of tantalum nitride from beta -TaN0.05 + gamma -Ta2N to cubic TaNx + delta -TaN. The VBXPS results indicate a charge transfer from Ta 5d to N 2p hands, and a decrease in the nitrogen vacancies concentration during the nitridation process. Copyright (C) 2000 John Wiley & Sons, Ltd.