The chemical structure of carbon nitride films fabricated by pulsed plasma-assisted chemical vapor deposition

Abstract

Carbon nitride films have been grown by a novel technique in which high power activation of the precursor gases is achieved by plasma generation with pulses of tens of nanoseconds lifetime. The effect of the substrate temperature on the chemical composition of films deposited from 13 sccm CH4+39 sccm N2 at a total pressure of 300 Pa is followed by X-ray photoelectron spectroscopy (XPS). N/C ratios between 0.33 and 0.37 characterize the material obtained at room temperature. Though the N content of the films steeply decreases with increasing substrate temperature, even those grown above 800 °C do contain a few at.%. The changes in the relative abundance of the individual spectral components of the C1s and N1s lines are interpreted in terms of changes in the chemical environment of the nitrogen and carbon atoms. Comparison of the results of the XPS analysis with pieces of information on surface morphology and local composition of the films derived from parallel SEM and X-ray microanalyses suggests that the deposits consist of a great variety of carbon microstructures of different shape and dimension embedded in a rather thin layer of higher nitrogen content.