Plasma-assisted deposition of metal and metal oxide coatings

Abstract

A combination of physical vapour deposition and plasma-assisted chemical vapour deposition techniques were used to deposit Cu-, Ni- and Sn-rich SnO/SnO2 coatings on metal and ceramic substrates. Cu and Ni were deposited on Al alloy 6061 substrates and Ni deposition was also performed on glass microscope slides and commercially pure alumina substrates. Sn-rich SnO/SnO2, on the other hand, was coated on stainless steel and pure Cu substrates. A direct-current plasma system was used to deposit the pure metals in vacuum with a resistively heated tungsten boat that was coated with alumina. All samples were sputtered for 20 min in an argon: hydrogen (1:1) atmosphere at a pressure of 300 mTorr. To reduce contamination and oxidation of both substrates and deposited layers, Cu and Ni coatings were made with argon: hydrogen (2:1) carrier gas. Sn-rich tin oxide coatings were deposited in a pure argon atmosphere (no hydrogen) to allow for the oxidation of Sn deposits on the stainless steel and copper substrates. Investigations of coated surfaces by scanning electron microscopy and X-ray diffraction showed coatings to be smooth, continuous and pure. Deposition rates showed this application to provide a very high rate when compared with chemical vapour deposition and metal-organic chemical vapour deposition techniques. Scratch tests results prove good attachment of the coatings to their respective substrates. (C) 1998 Chapman & Hall.