EFFECT OF DEPOSITION CONDITIONS ON THE CHEMICAL BONDING IN SPUTTERED CARBON NITRIDE FILMS

A balanced planar r.f powered magnetron sputter source has been used t o deposit carbon nitride films from a graphite target under various co nditions. Sample temperature, bias voltage and nitrogen content in the gas mixture were varied. The effects of oxygen, methane and ammonia o n the film growth were also studied. Special attention was paid to the effects of the deposition parameters on the structure of the films, i n particular the hybridisation of the carbon and nitrogen bonding. The chemical bonding of the carbon and nitrogen atoms was studied by elec tron energy loss spectroscopy (EELS). The chemical composition was eva luated by Rutherford back-scattering. The intensity of transitions to pi antibonding orbitals, as revealed by EELS, was found to increase wi th the nitrogen content in the films. Ion bombardment of the films dur ing growth and the addition of oxygen or hydrogen-rich gases further i ncreased the proportion of pi bonds of both the carbon and nitrogen at oms. It is suggested that the increase in the transitions to mu antibo nd orbitals is to be explained by increased sp(2) or possibly sp hybri disation of the carbon and nitrogen. Also, the effect of annealing on the bonding of nitrogen rich films after deposition was tested. The ch anges caused by nitrogen and deposition conditions are consistent with previous reports on the formation of paracyanogen structures.