Direct Ion Beam Deposition of Diamond-Like Films from RF Inductively Coupled (IC) Plasma Source: Mechanical, Electrical, and Optical Properties

Abstract

Diamond-like carbon (DLC) films were deposited on various substrates using direct ion beam deposition from an RF IC hydrocarbon plasma source. Combinations of gases such as CH₄. CH₄-N₂ were used to form plasma. The mechanical, electrical and optical properties of the films were examined as a function of deposition conditions and N₂ content in gas mixture. A small amount of N₂ (<8 sccm) did not markedly change hardness and stress, while electrical conductivity was significantly increased. In addition, a small amount of N₂ improved wear performance of the films reducing amount of debris and wear track size. Introduction of high N₂ flow into the system significantly deteriorates value of these parameters. It was found that N₂ essentially increases absorption coefficient, and reduces optical band gap. Analysis of the experimental results shows that observed effects can be explained by incorporation of N₂ into carbon-strained network that induces structural changes and. in turn, leads to an increase of sp² fraction in the DLC films.