A single quality factor for the deposition process of reactively sputtered thin a-C:H:N films G. Messina a , S. Santangelo a, * , A. Tagliaferro b , A. Tucciarone c a INFM, Dipartimento di Meccanica e Materiali, Facolt  a di Ingegneria, Universit  a ÔMediterraneaÕ, localit  a Feo di Vito, 89060 Reggio Calabria, Italy b INFM, Dipartimento di Fisica, Politecnico di Torino, corso Duca degli Abruzzi 24, 10129 Torino, Italy c INFM, Dipartimento di Scienze e Tecnologie Fisiche ed Energetiche, Universit  a di Roma ÔTor VergataÕ, via Tor Vergata 110, 00133 Rome, Italy Received 12 December 2001; received in revised form 19 June 2002 Abstract The carbon bonding modifications, produced by the different deposition conditions in nitrogenated a-C:H films (a-C:H:N) prepared by reactive-sputtering of a graphite target, are investigated by quantitatively analysing the evo- lution of the D- and G-bands in the Raman spectra. The film C content is evaluated and shown to depend on the many variables involved into the a-C:H:N film growth through a single quality factor, dimensionless combination of the dimensional process-variables. The film structural changes observed are understood in terms of the decreasing sp 3 :sp 2 ratio achieved with the diminishing film C content. The quality factor introduced, able to indicate how the variable- configuration can eventually change without significantly affecting the result in terms of C content and resulting film properties, represents a simple scaling law for the a-C:H:N film deposition, whose validity is preliminarily demonstrated for variations of rf power, total pressure and reactive-gas flow-rate in the ranges from 180 to 300 W, from 20 to 38 mTorr and from 5 to 27 sccm, respectively. A very simple model is therewith proposed accounting for the particular variable combination ultimately effective in determining the final issue of the deposition process. The generality of the proposed method is finally demonstrated. Ó 2002 Elsevier Science B.V. All rights reserved. PACS: 02.60.)x; 81.15.Cd; 78.30.Ly; 78.30.)j 1. Introduction In the last two decades, a considerable scientific and technological interest has been placed in both hydrogen-free (a-C) and hydrogenated (a-C:H) amorphous carbon films, whose outstanding phys- ical properties, such as chemical inertness, high electrical-resistivity and mechanical-hardness, low * Corresponding author. Tel.: +39-965 875 305; fax: +39-965 875 201. E-mail address: santange@mailer.ing.unirc.it (S. Santan- gelo). 0022-3093/03/$ - see front matter Ó 2002 Elsevier Science B.V. All rights reserved. doi:10.1016/S0022-3093(02)01892-6 Journal of Non-Crystalline Solids 318 (2003) 322–330 www.elsevier.com/locate/jnoncrysol