Hydrogenated amorphous carbon thin films deposition by pulsed DC plasma enhanced by electrostatic confinement

Abstract

Diamond-like carbon (DLC) is a metastable form of amorphous carbon with attractive properties such as high hardness, low friction, chemical inertness and high wear resistance. In this work, hydrogenated amorphous carbon (a-C:H) thin films were deposited using a plasma enhanced chemical vapor deposition technique by pulsed DC plasma with a simple, low-cost and efficient arrangement of multi-cathodes and multi-anodes in order to enhance the plasma by electrostatic confinement. The samples were characterized by Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy, Elastic Recoil Detection Analysis, Raman Spectroscopy, and nanoindentation measurements. a-C:H thin films show an homogeneous hydrogen profile along the films deposited at −600V and −800V and variable working pressure. According to Raman spectra, both the ID/IG ratio and the G-peak position increase at higher voltages (more remarkable dependence) and lower working pressures (less remarkable dependence). Moreover, the hardness depends on working conditions such as power supply voltage and total working pressure. The electrostatic confinement enhances the deposition rates of a-C:H thin films up to values of 0.9μm·h−1, which is almost double than those previously published by pulsed DC plasma in similar conditions. The Raman spectra follow the stage 2 of an established model and this structure transition may explain the hardness behavior.