Plasma chemical vapor deposition of thin carbon nitride films utilizing transport reactions

Abstract

Inductively coupled plasma chemical vapor deposition (ICP-CVD) has been used for the preparation of thin carbon nitride films from a solid carbon source (at floating potential) and nitrogen. Atomic nitrogen obtained as a result of the r.f. plasma activation interacts with the carbon source to form volatile carbon–nitrogen species. The latter are transported to the substrate where carbon nitride films are deposited in excess of atomic nitrogen. The supposed process mechanism was verified by microscopic observations of the carbon source before and after the process and by in situ mass spectrometric studies of the gas phase. The main advantage of the process is the possibility to obtain carbon nitride films with rates between 2 and 10 nm/min at rather low r.f. powers. The basic deposition parameters varied were the r.f. power (up to 100 W) and the working pressure in the reactor (up to 100 Pa). The surface topography of the films was studied by scanning electron microscopy (SEM) and atomic force microscopy (AFM); the deposited layers were found to be very smooth and uniform. The N/C ratio in the films was close to 1 as detected by Auger electron spectroscopy (AES) and elastic recoil detection (ERD) analysis. Infrared absorption and X-ray photoelectron spectra showed the presence of different carbon–nitrogen bonds in the layers.