Formation of diamond-like carbon films by 50 Hz sputtering from dual graphite targets

Abstract

Experiments on the growth of diamond-like carbon (DLC) films were carried out in a stainless steel chamber by means of 50 Hz sputtering from dual graphite targets following an original method, and using 200 mTorr, 3000 V, 50 mA and 4 h deposition time. Glass, copper and stainless steel plates were used in turn as the substrate, in orientations both parallel to and normal to the target plane. The temperature of the substrate was equilibrated with the argon plasma kinetic energy which controlled the deposition and etching rate. The films were characterized by means of transmission electron diffraction, optical microscopy and electrical resistance measurements. The films on stainless steel appeared transparent, yellow, brown and blue on different areas of the substrate where different deposition or etching parameters had been employed. Transmission electron diffraction analysis of the films confirmed the presence of a DLC cubic phase with a lattice constant of about 3.44 Å. The films on glass were transparent and yellow. The deposition rate was determined with an optical microscope and was found to be about 2–3 μm h -1. The electrical resistance in the direction normal to the film was measured through the polycrystalline copper substrate with a tungsten tip probe. This gave high values in the range 10–100 kΩ. This method is a promising alternative for DLC film growth because it is low cost and quite simple.