The dependence of hardness on the density of amorphous alumina thin films by PECVD

Smooth, uniform and transparent aluminum oxide films were deposited at low temperature (less than or equal to 500 degrees C) by r.f. plasma enhanced chemical vapor deposition (PECVD) with AlCl3, H-2 and CO2 as the reactants. The measurements of mechanical and optical properties demonstrate a potential application of PECVD aluminum oxide film as an optical protective coating, The variation of film hardness and density with deposition parameters is appal ent and shows a similar dependence while the composition stoichiometry is not so influenced. For amorphous thin films incorporating hydrogen and/or microvoid with no apparent variation on composition stoichiometry, the film hardness is dominated by density and a function near linear can be constructed as energy density is taken into account as an apparent character of hardness. (C) 1997 Elsevier Science S.A.