Journal of Non-Crystalline Solids 125 (1990) 293-301 293 North-Holland On the formation of silicon oxynitride by ion implantation in fused silica A. Carnera a, p. Mazzoldi a, A. Boscolo-Boscoletto a,1, F. Caccavale b, R. Bertoncello c, G. Granozzi c, I. Spagnol c and G. Battaglin d Unith CISM, Dipartimento di Fisica, Via Marzolo 8, 35131 Padova, Italy b Consorzio INFM, UniM di Padova, via Marzolo 8, 35131 Padooa, Italy c Dipartimento di Chimica lnorganica, Metallorganica ed Analitica, via Loredan 4, 35131 Padooa, Italy a Dipartimento di Chirnica Fisica, Calle Larga Santa Marta 2137, 30123 Venezia, and Unitgt CISM-Padova, Italy Received 2 February 1990 Revised manuscript received 8 June 1990 The formation of silicon oxynitrides and nitrogen gaseous compounds as a consequence of implantation of nitrogen ions in silica glasses was investigated by XPS analysis. The presence of gaseous compounds is supported by the analysis of the effect of a double implantation: a nitrogen implantation followed by an argon irradiation. Moreover SEM analysis shows, for doses higher than 6× 1017 N cm -2, a surface morphology characterized by blisters, which can be also ascribed to N-O or N 2 molecules. These structures are absent in the case of neon implantations. The distribution of nitrogen as a function of the implantation dose was measured by SIMS. With a dose > 5×1016 cm -2, the nitrogen distribution showed a flat profile limiting the maximum attainable nitrogen concentration and, consequently, the stoichiometry of the SiOxN ~ compound. An increase of the nitrogen concentration was obtained for nitrogen implantations in 29Si-preimplanted silica glasses. The nitrogen profile followed the distribution of the preimplanted silicon. I. Induction Chemical and physical transformations in- volved in ion implantation processes can be clas- sified on the basis of two aspects: (a) modifica- tions only related to energy deposition and inde- pendent of the nature of the incident ion; (b) modifications strongly dependent on the ions, be- cause of the formation of chemical bonds between them and target atoms [1]. In the former case, modifications are due to radiation induced com- positional changes occurring in the collisional cascade (radiation chemistry), while in the latter case processes equivalent to the so-called 'hot atom' chemistry induced by recoil atoms produced in nuclear reactions or radioactive decay are in- volved. The relative importance of each mecha- 1 Present address: Centro Ricerche Montedipe, via della Chimica 5, Porto Marghera (Venezia), Italy. nism depends on the characteristic parameters of the implantation processes (ion, energy, target temperature, current density) and on composition and structure of the target material. Thus, we expect different changes in mechanical and tribo- logical properties, in network dilatation, in in- duced optical absorption and luminescence, in compositional changes and modifications in chem- ical behavior as a function of differing experimen- tal conditions. Ion implantation in silica glasses usually results in an increase of the refractive index, n, due to a compaction effect [2,3]. However, a larger change of n is observed for implantation of nitrogen and this change has been attributed to the formation of silicon oxynitride [4-7]. More recently, some papers reported on the surface chemistry of silica glass implanted with both nitrogen and silicon ions and show the importance of chemical interac- tions in determining the final chemical state of the 0022-3093/90/$03.50 © 1990 - Elsevier Science Publishers B.V. (North-Holland)