Hybrid plasma system for diamond-like carbon film deposition

A novel hybrid plasma apparatus optimized for diamond-like carbon (DLC) fil m deposition is presented. A plasma was generated by use of a jet matrix pl asma source (JeMPS) operated at 13.56 MHz and up to 1 kW. The 48 plasma jet s were arranged as a hexagonal matrix within a 15-cm diameter circle. In th e center of an argon plasma at pressure of I mbar the ion concentration is 4.82 X 10(11) cm(-3). At a distance of 6 cm from the plasma source a water- cooled substrate holder biased with 13.56 MHz power was positioned. A plasm a-enhanced chemical vapor deposition (PECVD) process was used. Helium was u sed as a carrier gas excited in the jet matrix plasma;source. Methane, used as a source of carbon, was introduced in the zone between the plasma sourc e and the substrate holder. A fractal carrier and process gas distribution system allowed high film homogeneity. Typical gas flows were 500 and 100 se em, respectively; typical process pressure was 1 mbar. A Root's blower with a pumping speed of 250 m(3) h(-1) was used. A deposition rate of 78 nm min (-1) at room temperature was achieved. The him thickness variation over a 5 inch wafer was less than 7%. As the de bias of the substrate holder increa sed from 350 to 400 V the sp(2)/sp(3) ratio increased from 0.79 to 0.88. Th e refractive index of almost 2.4 and a Vickers hardness of 3000 were eviden ce of high quality DLC films. (C) 2000 Elsevier Science B.V. All rights res erved.