Study of the thermal stability of carbon nitride thin films prepared by reactive magnetron sputtering

CNx amorphous films have been prepared by reactive magnetron sputtering in a pure Nz discharge. The films grown on NaCl have been characterised by Fou rier transform infrared spectroscopy (IR), transmission electron microscopy (TEM), and electron energy loss spectroscopy (EELS). C/N atomic ratios hav e been determined by EELS with values in the range 2.0-1.2 for samples grow n under different conditions. The thermal stability of the films upon heati ng in vacuum was followed 'in situ' at the transmission electron microscope by EELS. This study has been completed by a thermogravimetric and mass spe ctrometer analysis of evolved gases upon heating in nitrogen flow and vacuu m, respectively. Under these conditions the films are stable up to 1023 K. Above this temperature the films decompose by elimination of nitrogen remai ning a carbonaceous residue. The thermal stability of the films upon anneal ing in air was studied by following the evolution of the X-ray photoelectro n spectroscopy (XPS) peaks during heating in air of films grown on steel. D econvolution analysis of the XPS spectra allows to determine the evolution of the different type of bonds. In particular pure carbon in the films appe ars more reactive to oxygen than C = N and C-N bonds. (C) 2000 Elsevier Sci ence S.A. All rights reserved.