Growth and erosion of amorphous carbon (a-C:H) films by low-temperature laboratory plasmas containing H and N mixtures

Abstract

Growth and erosion of amorphous hydrogenated carbon (a-C:H) films from nitrogen-containing gas mixtures was studied in an electron-cyclotron-resonance low-temperature plasma. Deposition and erosion rates were measured as a function of nitrogen admixture and ion energy. At low energy, N2 addition to methane plasmas causes a reduction of the deposition rates that does not exceed significantly the expected reduction due to dilution. At higher ion energies the deposition rate reduces further and finally switches to net erosion. Erosion of a-C:H films in N2/H2 mixtures is much more efficient than in pure H2 and N2. The erosion rate drops with increasing N2 admixture almost proportional to the total ion flux if the substrate is at floating potential. For higher ion energies the erosion rate dramatically increases and shows a clear maximum at around 25% N2 flow ratio.