High Rate Deposition of Thick Oxide Layers on Plastic Substrates

摘要

Plastic materials have optical clarity and the processing benefits of a thermoplastic, but lack abrasion resistance. Al_2O_3 as well as SiO_x layers perform very well as clear abrasion resistant layers. The typical layer thickness ranges from 1μm to 6μm. High deposition rates at an appreciate layer quality can be reached by application of the Hollow cathode Activated Deposition (HAD) process. The HAD process is based on the reactive evaporation of oxide or metal with high rates in combination with a hollow cathode plasma activation. The hollow cathode plasma source generates an arc discharge plasma with very high plasma densities in the order of 10~(12) cm~(-3). For insulating substrates a high self bias potential of about 15V is obtained. The typical deposition rates are: 100-150nm/s for Al_2O_3 and 300-600nm/s for SiO_x. The deposited layers show a dense, amorphous structure and the microhardness (measured by nanoindentation) amounts to 6GPa for Al_2O_3 layers respectively 3GPa for SiO_x. Regardless of the different hardnesses the abrasion resistance performs very well for both oxides.