Study of SHI induced recrystallization effects in SOI structures synthesized by nitrogen and oxygen ion implantation in silicon A.D. Yadav a, * , Rucha H. Polji a , S.K. Dubey a , Saif A. Khan b , D.K. Avasthi b a Department of Physics, University of Mumbai, Vidyanagari campus, Santacruz (E), Mumbai 400 098, India b Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110 067, India article info Article history: Received 29 March 2008 Received in revised form 23 August 2008 Accepted 1 September 2008 Keywords: SOI Buried layer Swift heavy ions Recrystallization HRXRD Pacs: 61.10.Ai 61.72.Tt 61.80.Jh 78.30.Am 81.10.Jt 87.64.Je abstract Silicon oxynitride (Si x O y N z ) buried insulating layers were synthesized by implantation of nitrogen ( 14 N þ ) and oxygen ( 16 O þ ) ions sequentially in the ratio 1:1 at 150 keV to ion-fluences ranging from 1  10 17 to 5  10 17 cm 2 to prepare silicon on insulator (SOI) structures. The as implanted samples were held at 270  C and irradiated to total fluence of 1  10 14 cm 2 by 60 MeV Ni þ5 to study the structural changes/ recrystallization of SOI structures induced by swift heavy ion (SHI) irradiation. Fourier transform infrared (FTIR) measurements on the as implanted samples (1  10 18 cm 2 ) show a single absorption band in the wavenumber range 1300–750 cm 1 attributed to the formation of silicon oxynitride (Si–O–N) bonds in the implanted silicon. It is observed that a nitrogen rich silicon oxynitride structure is formed after SHI irradiation. The study of X-ray rocking curves on the samples show the formation of small silicon crystallites due to swift heavy ion irradiation. Ó 2008 Elsevier Ltd. All rights reserved. 1. Introduction Silicon on insulator (SOI) structures have attracted significant research interest for future nanometer scale devices. The produc- tion of SOI structures using ion beam techniques has great potential for applications in semiconductor devices. The SOI substrates can be obtained by high fluence (10 17 –10 18 cm 2 ) ion implantation of nitrogen and/or oxygen ions into silicon (Si) at 100–200 keV energy to synthesize buried insulating (Si–O–N) layer. However, the process results in amorphization and production of defects in the top silicon surface layer. Thus, an annealing step is required for the recrystallization of top silicon layer and removal of defects in the buried Si–O–N layer to develop SOI structures. Normally thermal annealing of SOI structures at high temperatures (1200  C) is required for recrystallization and removal of defects but some residual defects even remain after high temperature annealing. Currently the ion-beam-induced epitaxial crystallization (IBIEC) is being investigated as an alternative low temperature method, for damage recovery of ion-implanted materials. Nakata et al. have reviewed the low temperature crystallization phenomenon on the basis of possible mechanism of inelastic scattering process during IBIEC in Silicon [1] and it has been shown to take place in silicon and other materials at considerably lower target tempera- tures than necessary for thermal annealing. Virdi et al. have reported the improvement of the buried Si 3 N 4 -Si interfaces and the top silicon layer of the SOI structures synthesized by high fluence nitrogen implantation after irradiation with 100 MeV 107Ag [2]. The heavy ion-beam-induced epitaxial recrystallization of buried Si 3 N 4 layers has been studied by high-resolution transmission electron spectroscopy and selected area diffraction [3]. Virdi et al. have reported the improvement of the buried Si 3 N 4 –Si interfaces and the top silicon layer of the SOI structures synthesized by high fluence nitrogen implantation after irradiation with 100 MeV 107Ag [2]. Rutherford backscattering spectrometry and Micro- Raman spectroscopy investigations have demonstrated the epitaxial recrystallization of 200 nm amorphous Si layers after swift heavy ions (50 and 100 MeV Au 8þ ) [4]. Intarasiri et al. have * Corresponding author. Tel.: þ91 22 26526250/26528835; fax: þ91 22 26529 780. E-mail addresses: adyadav@physics.mu.ac.in, drad_yadav@yahoo.com (A.D. Yadav). Contents lists available at ScienceDirect Vacuum journal homepage: www.elsevier.com/locate/vacuum 0042-207X/$ – see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.vacuum.2008.09.008 Vacuum 83 (2009) 889–891