Protective diamond-like coatings for optical materials and electronic devices

The mechanical and protective properties of plasma enhanced chemical vapor deposition (PECVD) a-C:H films were studied in terms of their use as wear r esistant and chemically inert coatings for optical and electronic products, The effect of the discharge power and gas mixture composition on the hardn ess and wear resistance of a-C:H films, as well as on the level of mechanic al stresses in the film-substrate system, has been studied. By varying the synthesis parameters we have succeeded in obtaining films of hardness up to 16 GPa. Diamond-like films are shown to exceed monocrystalline silicon in wear resistance. Internal stresses in the film-substrate system attain 1 GP a. The introduction of nitrogen into the methane-hydrogen gas mixture cause s the strength to increase and internal stresses to halve. Atomic force mic roscopy (AFM) was used to study variations in the surface morphology of a-C :H films synthesized under different conditions. The stability of a-C:H fil m to annealing in the air, light irradiation, chemically active etching sol utions, and to environmental factors (enhanced humidity, salt fog, temperat ure, dynamic dust, etc.) was also studied. Diamond-like carbon (DLC) films have been applied to germanium products as external protective layers of in frared multilayer antireflection coatings. The use of DLC film as a barrier coating for the heating layer of inkjet print cartridges has enabled a ten fold increase in service life. (C) 2000 Elsevier Science S.A. All rights re served.