Wear and adhesion of PEALD titanium molybdenum nitrides: Effects of film-substrate interface

Plasma enhanced atomic layer deposited (PEALD) ternary transition metal nitride thin films have shown potential as tribological coatings with low friction and wear. However, relationships between PEALD process parameters and film adhesion and wear are not well understood and limit the use of these materials in engineering applications . In this study, we investigate the influence of substrate material , surface oxide interlayer thickness, and pre-deposition surface treatments on the adhesion and wear behavior of PEALD Ti x Mo 1-x V (x = 0.5, hereafter referred to as TiMoN) films. Results show that wear rate and adhesion are inversely related, with the lowest wear rates (∼4 × 10 −8 mm 3 /Nm) and adhesion for coatings grown on a native silicon surface. XRR and XRD measurements on all TiMoN coatings showed that the crystallite size , density, and average lattice spacing were not statistically different, indicating that changes to the substrate material and pre-deposition cleaning parameters do not alter the structure of the films. However, residual stresses were found to be affected by the surface preparation and substrate material, resulting in lower compressive stresses on native oxide substrates and higher on the etched substrates. These results show that there is an inverse relationship between film stress and adhesion, and a direct relationship between film stress and wear rate; variations within these trends are due to substrate surface preparation. The combined material properties and tribological behavior of these films, along with angstrom level thickness control and low deposition temperatures , make them promising multifunctional nanomaterials for applications in MEMS/NEMS and thermally sensitive microelectronics.