Vacuum 82 (2008) 116–120 Ion sputtering rates of C, Cr x C y , and Cr at different Ar + ion incidence angles A. Zalar à , J. Kovacˇ, B. Pracˇek, P. Panjan, M. C ˇ eh Jozˇef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia Abstract To study the ion sputtering of a layered structure with different layer densities and ion sputtering yields a trilayer structure of C-graphite(46 nm)/Cr x C y (60 nm)/Cr(69 nm) was sputter deposited onto smooth silicon substrates. The ion sputtering rates of amorphous carbon, amorphous Cr x C y and polycrystalline Cr were determined by means of Auger electron spectroscopy depth profiling as a function of the angle of incidence of two symmetrically inclined 1 keV Ar + ion beams in the range between 221 and 821. The sputtering rates were calculated from the known thicknesses of the layers and the sputtering times necessary to remove the individual layers. It was found that the sputtering rates of C-graphite, Cr x C y carbide and Cr were strongly angle dependent. The experimental sputtering yields were in agreement with the theoretical results obtained by calculation of the transport of ions in solids, but the sputtering yields of C-graphite measured at ion incidence angles larger than 291 were smaller than the simulated ones. r 2007 Elsevier Ltd. All rights reserved. Keywords: Sputtering rates; Sputtering yields; Carbon; Chromium carbide; AES depth profiling 1. Introduction Metal carbides such as chromium carbides are a known group of compounds which have been used as coatings and component parts of steels and composite materials [1–3]. Their unique physical and chemical properties like high melting point, extreme hardness, low coefficient of friction and chemical inertness make them candidates for wear- and corrosion-resistant coatings [4,5]. The properties of coatings are influenced by their microstructure and composition which are dependent on the deposition technique used, such as physical vapour deposition (PVD), chemical vapour deposition (CVD), plasma spray- ing or other. Using the same deposition technique, the microstructure and the composition of carbides are dependent on deposition parameters such as a reactive gas pressure, substrate temperature, power, and sputtering system geometry [6–8]. However, despite further progress in surface analytical methods, the structure and the composition of the carbides formed are in many cases not yet well determined [5,9,10]. For depth profiling one of the surface analytical techniques like Auger electron spectrtoscopy (AES), X-ray photoelectron spectroscopy (XPS) or secondary ion mass spectroscopy (SIMS) is combined with ion sputtering of the sample. Salaita and Hoflund [11] studied dynamic SIMS using 4 keV Xe + performed on three different carbon carbides in order to determine if SIMS might be useful in distinguishing between Cr carbides with different compositions. They concluded that ion sputtering can dramatically alter the composition of the damage region and produce ion yields which do not correlate with the bulk stoichiometry. It is worth noting that the ion sputtering yields of carbon and metal carbides are not generally known, especially not over a large range of ion incidence angles. In this work, we studied the influence of ion incidence angle on the ion sputtering rates and ion sputtering yields of amorphous C-graphite, amorphous chromium carbide and polycrystalline Cr in the C-graphite/Cr x C y /Cr trilayer. The composition and the crystalline structure of the trilayer were investigated using AES, XPS and transmission ARTICLE IN PRESS www.elsevier.com/locate/vacuum 0042-207X/$ - see front matter r 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.vacuum.2007.07.015 à Corresponding author. Tel.: +386 1 477 34 02; fax: +386 1 477 34 40. E-mail address: anton.zalar@ijs.si (A. Zalar).