Deposition of tetrahedral hydrogenated amorphous carbon using a novel electron cyclotron wave resonance reactor

Abstract

Highly tetrahedral hydrogenated amorphous carbon (ta-C:H) is deposited with a novel, 13.6 MHz excited electron cyclotron wave resonance (ECWR) plasma source. The ion flux of an acetylene and a nitrogen plasma was investigated by mass spectrometry and retarding field measurements. The ECWR gives a dissociation degree between 15% and 80% depending on gas flow rate. Ion current densities up to 2 mA/cm2 can be achieved, corresponding to ta-C:H deposition rates of 2 nm/s. The fraction of sp3 bonded carbon atoms and mass density are strongly related to the amount of hydrogen in the ion flux. For low hydrogen ion fluxes (10%), a sp3 fraction of 70% and a mass density of 2.85 g/cm3 can be achieved. At higher hydrogen ion fluxes (40%), the sp3 fraction and the mass density fall to 55% and 2.55 gm/cm3, respectively.