Adherent amorphous hydrogenated carbon films on metals deposited by plasma enhanced chemical vapor deposition G. Capote a, ⁎ , L.F. Bonetti a,b , L.V. Santos a , V.J. Trava-Airoldi a , E.J. Corat a a Instituto Nacional de Pesquisas Espaciais (INPE), Laboratório Associado de Sensores e Materiais (LAS), Av. dos Astronautas, 1758-São José dos Campos, 12227-010, SP, Brazil b Instituto Tecnológico de Aeronáutica, Centro Técnico Aeroespacial, São José dos Campos-SP, Brazil Received 8 March 2006; received in revised form 12 July 2007; accepted 2 August 2007 Available online 11 August 2007 Abstract This paper reports the findings of a study of the structural, mechanical, and tribological properties of amorphous hydrogenated carbon (a-C:H) coatings for industrial applications. These thin films have proven quite advantageous in many tribological applications, but for others, thicker films are required. In this study, in order to overcome the high residual stress and low adherence of a-C:H films on metal substrates, a thin amorphous silicon interlayer was deposited as an interface. Amorphous silicon and a-C:H films were grown by using a radio frequency plasma enhanced chemical vapor deposition system at 13.56 MHz in silane and methane atmospheres, respectively. The X-ray photoelectron spectroscopy technique was employed to analyze the chemical bonding within the interfaces. The chemical composition and atomic density of the a-C:H films were determined by ion beam analysis. The film microstructure was studied by means of Raman scattering spectroscopy. The total stress was determined through the measurement of the substrate curvature, using a profilometer, while micro-indentation experiments helped determine the films' hardness. The friction coefficient and critical load were evaluated by using a tribometer. The results showed that the use of the amorphous silicon interlayer improved the a-C:H film deposition onto metal substrates, producing good adhesion, low compressive stress, and a high degree of hardness. SiC was observed in the interface between the amorphous silicon and a-C:H films. The composition, the microstructure, the mechanical and tribological properties of the films were strongly dependent on the self-bias voltages. The tests confirmed the importance of the intensity of ion bombardment during film growth on the mechanical and tribological properties of the films. © 2007 Elsevier B.V. All rights reserved. Keywords: Amorphous hydrogenated carbon; Plasma enhanced chemical vapor deposition; Silicon interlayer; Adhesion; X-ray photoelectron spectra; Mechanical properties 1. Introduction Diamond-like carbon (DLC) coatings have attracted signif- icant attention recently due to their low friction, high degree of hardness, chemical inertness, and high wear resistance [1]. Currently DLC film deposition can be accomplished econom- ically at low temperature, utilizing various chemical vapor deposition techniques, sputtering methods, arc-discharge, pulsed laser deposition and ion beam assisted deposition tech- niques [1]. Plasma synthesis of coatings is a powerful, versatile way to obtain such materials. Among DLC films, the amor- phous hydrogenated carbon (a-C:H) coatings stand out due to their attractive tribological properties which may be by specific settings to meet the plasma conditions and deposition technique [2]. Amorphous hydrogenated carbon films are mostly obtained by plasma decomposition of a hydrocarbon-rich atmosphere. It is usually accepted that surface chemisorption of carbon carrying neutral radicals is the main channel for the film growth [3]. In a-C:H films deposited by methane decomposition, the structure is composed of sp 2 hybridized clusters interconnected by sp 3 hybridized carbon atoms. Furthermore, the mechanical properties (e.g. hardness, Young's modulus, adhesion to the substrate, internal stresses) as well as important electronic Available online at www.sciencedirect.com Thin Solid Films 516 (2008) 4011 – 4017 www.elsevier.com/locate/tsf ⁎ Corresponding author. Tel.: +55 12 3945 6579; fax: +55 12 3945 6717. E-mail address: capote@las.inpe.br (G. Capote). 0040-6090/$ - see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.tsf.2007.08.007