Amorphous, hydrogenated carbon films and related materials - plasma deposition and film properties

Plasma deposition and properties of a-C:H are reviewed and recent results on the process characterization are reported. The role of process gas, plasma chemistry and plasma surface interaction is discussed. It is shown that the deposition energy of the hydrocarbons is the most critical deposition parameter in determining the film properties. The ion energy distribution in rf-glow discharge deposition has been investigated. For comparison, a-C:H films have been deposited from monoenergetic ion beams. Hard a-C:H films with precursor-independent properties are obtained if the deposition energy is large enough to allow for efficient fragmentation of the energetic hydrocarbons at the film surface. Otherwise, soft polymerlike films are obtained at low deposition energies. As a key for the understanding of the a-C:H properties, hydrogen incorporation, carbon bonding and network structure are discussed. Chemical substitution of hydrogen and carbon in a-C:H are shown to result in related materi als with an increased range of physical properties.