Preparation of hydrogenated diamond-like carbon films using high-density pulsed plasmas of Ar/C₂H₂ and Ne/C₂H₂ mixture

Abstract

Hydrogenated diamond-like carbon films are prepared using reactive high-density pulsed plasmas of Ar/C 2 H 2 and Ne/C 2 H 2 mixture in the total pressure range from 0.5 to 2 Pa. The plasmas are produced using a reactive high-power impulse magnetron sputtering (HiPIMS) system. A negative pulse voltage of %500 V is applied to the substrate for a period of 15 µs in the afterglow mode. The growth rate does not strongly depend on the type of ambient gas but it markedly increases to about 2.7 µm/h at a C 2 H 2 fraction of 10% and a total pressure of 2 Pa with increasing C 2 H 2 fraction. The marked increase in the growth rate means that the HiPIMS system can be regarded as a plasma source for the chemical vapor deposition process. The hardness of the films prepared by Ne/C 2 H 2 plasmas is somewhat higher than that of the films prepared by Ar/C 2 H 2 plasmas under the same operating conditions, and the difference becomes larger as the pressure increases. The hardness of the films prepared by Ne/C 2 H 2 plasmas ranges between 11 and 18 GPa. In the Raman spectra, two very broad overlapping bands are assigned as the G (graphite) and D (disorder) bands. The peak position of the G band is roughly independent of the total pressure, whereas the FWHM of the G peak decreases with increasing total pressure as a whole.

Synthesis of hydrogenated diamondlike carbon thin films using neon–acetylene based high power impulse magnetron sputtering discharges

“…The potential of HiPIMS has been explored for the production of DLC thin films by several authors and it has shown promising results. [13][14][15][16][17][18] However, conventional Ar-C HiPIMS discharges have been found to exhibit significantly smaller degree of ionization of sputtered material 14 as opposed to their Ar-metal counterparts 19,20 rendering HiPIMS insufficient for synthesizing high quality DLC films. We have recently addressed this challenge 21 by developing a novel Nebased HiPIMS process; the presence of Ne as a sputtering gas resulted in a substantial increase of the electron temperature as compared to Ar-based HiPIMS process.…”

A Strategy for Alleviating Micro Arcing during HiPIMS Deposition of DLC Coatings

“…The main goal was to obtain hard coatings with low friction coefficients and wear rates, and with smooth surface. Two main approaches were followed and combined for tuning the process: (i) addition of Ne into the gas mixture, in order to improve the C ionization [18,34] and (ii) use of acetylene to increase the deposition rate through the contribution of C atoms from decomposition of gas precursor [10,35].…”

“…One of the main factors determining the sp 3 bonding in DLC is the ion bombardment, with an optimum energy around 100 eV for impinging C + ions [9]. For the hydrogenated coatings in particular, where some of the carbon-carbon bonding can be converted into carbon-hydrogen, the bombardment with a sufficient number of ions that have the appropriate kinetic energy becomes even more important in increasing the fraction of sp 3 bonds [10]. For the case of magnetron sputtering, significant ionization of sputtered atoms can be usually achieved by applying high power pulses, technique known as high power impulse magnetron sputtering (HiPIMS) [11][12][13][14].…”

“…The increased ionization provided by HiPIMS is beneficial also in reactive deposition of DLC. The use of a reactive environment by the addition of acetylene, to either Ar, Ar/Ne or Ne environment was demonstrated in obtaining hydrogenated DLC coatings with low hydrogen content, with hydrogen contents up to 15%-20% [10,25]. In that case, the HiPIMS plasma activates the reactive gas precursor.…”

Density and microstructure of a-C thin films

“…In another study with rather high frequency (250 Hz to 1 kHz), the plasma was found to have larger ionized species yielding enhance densification with larger sp 3 fraction [9]. In more recent, works Ar and C 2 H 2 gas mixture were used to deposit a-C films but films were not H free [13,14]. Clearly, HiPIMS offers possibilities to deposit carbon thin films with high density and high sp 3 fractions, and more systematic studies are required to achieve this.…”