Large-area, high-rate deposition of thin amorphous carbon films using a novel controlled plasma reactor

The hard forms of amorphous carbon and hydrogenated amorphous carbon, also referred to as diamond-like carbons, have many present applications as hard, transparent and inert materials. Currently, these are most often used as protective coats for magnetic recording discs, antireflective coatings for infra-red windows and flat panel displays. Thin films of highly-tetrahedral (sp(3)-bonded) hydrogenated amorphous carbon (ta-C:H) have been successfully deposited on various substrates employing a novel electron-cyclotron-wave-resonance controlled plasma reactor (COPRA). The latter is a high-frequency, magnetically-confined, low-pressure plasma-beam source in which the ion energy, ion current density and degree of ionization can be monitored independently of each other over a wide range. COPRA has been designed for thin-film deposition and specifically for the formation of ta-C:H and poly-crystalline diamond. The main technical attributes of COPRA are the high deposition rate (up to 4 nm/s) over large areas (500 mm in dial, coupled with good process control and reproducibility. Analyses have demonstrated that the resulting ta-C:H films have up to 80% sp(3) sites, maximal density of 2.90 g/cm(3), roughness < 0.5 nm, Young modulus of 290 and hardness of 61 Gpa. The minimal thickness necessary for obtaining a continuous coating has been 3 nm. This combination of excellent physical properties makes the ta-C:H films fabricated by means of COPRA superiour to the diamond-like layers produced using conventional plasma-deposition facilities. A notable feature of COPRA is its ability to also deposit, with good uniformity and reproducibility, other materials of high technological importance such as cubic boron nitride, carbon nitride, silicon nitride, silicon oxynitrides etc.