Adhesion of Ti and TiC Coatings on PMMA Subject to Plasma Treatment: Effect of Intermediate Layers of Al₂O₃ and TiO₂ Deposited by Atomic Layer Deposition

Abstract

Abstract Magnetron sputtered metal and metal compound films generally show very poor adhesion to PMMA; this limits the use of the polymer for components which are wear or scratch resistant or have a decorative finish. We have shown that adhesion could be significantly improved by a duplex process where a nanometer‐scale thickness adhesion layer of TiO 2 or Al 2 O 3 was deposited by low temperature atomic layer deposition (ALD) prior to magnetron sputtering. The metal precursors used for TiO 2 and Al 2 O 3 were TDMAT and TMA, respectively, and ozone was used as a source of oxygen in both processes. This process was followed by deposition of the metal/metal carbide layer using pulsed DC reactive magnetron sputtering. With the presence of the ALD adhesion layer, the pull‐off adhesion strength increased with its thickness until a point where the failure mechanism was due to cohesive disruption of the substrate material itself. It has been shown that the ALD deposited layers protect the PMMA against plasma damage during the sputtering process by blocking both direct ion damage and disruption of the polymer structure by ultra‐violet radiation. magnified image