Synthesis of carbon nitride films by high-density helicon wave-excited plasma sputtering

Properties of high-density nitrogen plasmas with excitation of the m = 0 mo de helicon wave has been studied for reactive plasma sputter synthesis of c arbon nitride films. High-density nitrogen plasmas with densities of 4 X 10 (12) cm(-3) were obtained in nitrogen at similar to0.1 Pa. Optical emission spectroscopy showed that the line emissions of atomic nitrogen (NI) and at omic-nitrogen ions (NII) were considerably enhanced in the helicon wave-exc ited high-density plasma, whereas, the spectra measured from the induction- mode (non-wave excitation) low-density plasma were dominated by those of th e molecular band emission associated with the first positive system of N-2. Carbon nitride films have been deposited on Si (100) substrates by reactiv e sputtering of carbon target with the helicon wave-excited high-density ni trogen plasmas at similar to0.1 Pa. Compositional characterizations of the CN films were performed using Rutherford backscattering spectrometry (RBS). The RBS analysis showed that the N/C ratio of similar to1.3 was achieved b y depositing the CN films at plasma densities as high as 1 X 10(12) cm(-3), where the line emissions of atomic nitrogen were significantly higher than the molecular band emissions. Increase in the plasma density and/or the em ission-intensity ratio of the atomic nitrogen (NI) to the molecular band in the vicinity of the substrate was found to directly contribute to the N/C composition ratio in the CN films. Structural analysis by Fourier transform infrared spectroscopy (FTIR) showed that the bonds associated with hydroge n impurity could be effectively eliminated by increasing the substrate temp erature during film depositions. (C) 2001 Elsevier Science B.V. All rights reserved.