FORMATION OF C-N THIN-FILMS BY ION-BEAM DEPOSITION

Thin carbon-nitrogen films have been formed by direct impingement of 5-100 eV C+ and N+ or N-2(+) ions upon solid surfaces, as well as by 5-350 eV N+ bombardment of graphite surfaces. The influences of ion energy, N+/C+ arrival rate, and type of substrate have been studied. The films deposited in this manner are found to be essentially amorphous, with some graphitic regions on the scale of a few nm. Two distinct types of C-N bonding, one attributed to graphitelike local structure (C-N pi bonds) and one attributed to C3N4-like local structure (C-N sigma bonds), have been detected by x-ray photoelectron spectroscopy. Films deposited by dual-beam deposition and single-beam nitridation at 75 eV or less exhibit differences in the single-bonded structure. Total nitrogen concentrations of up to 47 at. % have been measured by Auger electron spectroscopy (AES) and Rutherford backscattering spectrometry. The C KVV Auger line shapes of the two phases have been determined by factor analysis. These line shapes are consistent with the expected band structures for the two phases. Film growth is consistent with a combined surface deposition/subplantation model, with high incident energies resulting preferentially in damage to the C3N4-like phase. A significant amount of disorder is present in all of the films, as indicated by AES line shapes and transmission electron microscopy analysis. Preferential sputtering of N is observed during AES depth profiling with a 1 keV Ar+ beam. Implications of this work for deposition of C-N films by energetic particle bombardment are discussed. (C) 1995 American Vacuum Society.