Stress and Surface Fluid Contact Angle Analysis on Ultrananocrystalline Diamond (UNCD) Films grown by Hot Filament Chemical Vapor Deposition (HFCVD)

The research described in this article focused on investigating the influence of three gas mixtures on the growth of ultrananocrystalline diamond (UNCD) films, using hot filament chemical vapor deposition (HFCVD). The focus was on residual stress analysis and measurement of fluid drop contact angle on UNCD films’ surfaces. Three films were grown using different flow rates of hydrogen (H<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>), methane (CH<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</inf>), and argon (Ar) gas mixtures. The chemical, structural, and residual stress properties of the UNCD films were characterized using Raman and X-ray Photoelectron Spectroscopies (XPS), X-ray diffraction (XRD), and Scanning Electron Microscopy (SEM), respectively. The hydrophilicity and hydrophobicity of the surfaces were evaluated through water drop contact angle measurements. The results show that the gas mixture has a significant impact on the residual stress and wettability properties of the UNCD films. In particular, the H<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> flow rate and the addition of Ar gas flow influence the formation of more homogeneous surfaces and the variation of residual stress, which is crucial for applications to microelectromechanical systems (MEMS) and other advanced UNCD film-based technologies.