STUDY OF THE CHEMICAL-COMPOSITION AND MICROSTRUCTURE OF ION BEAM-DEPOSITED CNX FILMS INCLUDING AN XPS C 1S PEAK SIMULATION

The chemical composition and microstructure of dual ion beam-deposited CNx films with nitrogen contents in the range 20-33 at.% have been ex amined by Fourier transform infrared spectroscopy (FTIR) and x-ray pho toelectron spectroscopy (XPS). The FTIR spectra together with other pu blished data have been used to construct a model microstructure of the CNx films. The XPS N Is peak is composed of two components correspond ing to N-sp(2) C and N-sp(3) C bonds. Using the quantified N Is data a nd making certain assumptions, the model microstructure has been used as the basis of a C Is peak simulation in which nine C components have been combined. At an N content of 20 at.% the simulation agrees well with the experimentally recorded XPS C Is peak. The FTIR spectra, XPS N Is peak shape and C Is peak simulations support a chemical structure of N substitution in an amorphous sp(2)/sp(3) hybridized carbon struc ture. Above an N content of similar to 20%, a new (nitrile-like) chemi cal form also emerges in the material, its abundance increasing with N content. It is proposed that this new structure occurs due to the pre sence, in the surface region of the condensing film, of C = N diners, which are formed when a C atom is surrounded by many N atoms. This mol ecule becomes trapped in the material and bonds to atoms at neighbouri ng sites. (C) 1997 by John Wiley & Sons, Ltd.