Effect of Nitrogen on the Growth of Carbon Nitride Thin Films Deposited by RF Plasma Enhanced Chemical Vapor Deposition

Carbon nitride thin films were deposited by RF plasma enhanced chemical vapor deposition using acetylene (C2H2) and nitrogen (N-2) mixture on Si (1 0 0) substrates. The films were deposited at 400 degrees C substrate temperature, 600 W RF power with 5 sccm C2H2 and different flow ratio of N-2 (5, 15, 30, 60) sccm. The deposition rate was characterized by surface profilometer, composition and bonding structure were characterized by EDS, Raman spectroscopy and Fourier transform infrared spectrometry (FTIR) and microstructure by Atomic Force Microscopy (AFM). The deposition rate decreased with the increase in nitrogen content. Nitrogen content of 15 atom% could be incorporated in the film at 60 sccm N-2. Deposition rate and roughness was found to decrease with the increase of nitrogen ratio. Spectroscopic studies confirmed the incorporation of nitrogen (C=N, C N) in the film and the amount of CN bonding was found to increase with increase of nitrogen content. AFM studies showed decrease of particle size with increase of nitrogen content in the precursor gas. All films were found to be X-ray amorphous. The atomic resolution picture from AFM of films confirmed the formation of C3N4 phase in the carbon nitride film.