Influence of carbon ionization increment by adding ne on the bonding, electrical, and tribological properties of carbon thin films deposited by HiPIMS

In this work, we use mass quadrupole spectroscopy to analyze the ion energy distribution function for C⁺ ions from different gas composition discharges (20, 40, 60, 80, and 90% Ne) + Ar in a plasma sputtering process. Carbon films were obtained for each gas composition discharge. The carbon bonding structure of films was analyzed by Raman spectroscopy using deconvolution fitting of the G and D Raman peaks. The C-sp³ content was correlated with the electrical and tribological properties of the carbon films. Our results further corroborate the enhancement of carbon ionization in HiPIMS processes by adding neon in conventional argon gas during the deposition process. Furthermore, we found that excessive levels of carbon ionization were detrimental in the formation of C-sp³ decreasing the resistivity, and indicating the decrement of the elastic modulus of the samples. In addition, the use of neon in the gas working mixture increased the deposition rate significantly compared to argon-only processes from 1.7 to 3.22 nm/min for the highest deposition rate cases. Tribology showed that an intermediate C-sp³ content in the carbon films developed desirable tribological behaviors with lower friction coefficients and wear rates, revealing that higher values of C-sp³ content are not necessarily for robust solid lubricious and wear resistance.