Deposition of silicon oxynitride at room temperature by Inductively Coupled Plasma-CVD Luı ´s da Silva Zambom a, * , Patrick Verdonck b,1 a MPCE-Faculdade de Tecnologia de Sa ˜o Paulo—CEETEPS, Pc ¸a Coronel Fernando Prestes, 30, Sa ˜o Paulo—CEP 01124-060, Brazil b PSI-LSI-Escola Polite ´cnica da Universidade de Sa ˜o Paulo, Brazil Available online 20 January 2006 Abstract Oxynitride thin films are used in important optical applications and as gate dielectric for MOS devices. Their traditional deposition processes have the drawbacks that high temperatures are needed, high mechanical stresses are induced and the deposition rate is low. Plasma assisted processes may alleviate these problems. In this study, oxynitride films were deposited at room temperature through the chemical reaction of silane, nitrogen and nitrous oxide (N 2 O), in a conventional LPCVD furnace, which was modified into a high density Inductively Coupled Plasma (ICP) reactor. Deposition rates increased with applied coil power and were never lower than 10 nm/min, quite high for room temperature depositions. The films’ refractive indexes and FTIR spectra indicate that for processes with low N 2 O gas concentrations, when mixed together with N 2 and SiH 4 , nitrogen was incorporated in the film. This incorporation increased the resistivity, which was up to 70 GV cm, increased the refractive index, from approximately 1.47 to approximately 1.50, and decreased the dielectric constant of these films, which varied in the 4 – 14 range. These characteristics are adequate for electric applications e.g. for TFT fabrication on glass or polymers which can not stand high temperature steps. D 2005 Elsevier B.V. All rights reserved. PACS: 73.61.Ng; 77.22.Ch; 78.66.Nk; 81.15.Gh Keywords: Silicon oxynitride; Thin films; Inductively Coupled Plasma Enhanced Chemical Vapour Deposition 1. Introduction Oxynitride thin films are used in important applications such as protective layers and insulators for optical devices such as low-pass and high-pass band pass filters and optical communication waveguides [1–4] and for gate dielectrics. Their traditional deposition processes have several drawbacks: high temperatures are needed, they induce high mechanical stresses and have a low deposition rate [5]. Plasma assisted processes may produce films of similar characteristics at much lower temperatures [2,6]. However, one must be aware of possible drawbacks such as lower density–higher porosity, lower resistivity etc. Alternative processes have been proposed to decrease the drawbacks of traditional deposition, such as oxidation of silicon substrates and nitridation in inductively coupled nitrogen plasmas [7,8]. By controlling the composi- tion of these films, it is possible to adjust several character- istics such as the band gap, dielectric constant, stress, density and refractive index that are important for the device performance [9]. In an earlier study, a conventional Low Pressure Chemical Vapour Deposition (LPCVD) furnace was adapted into a high density Inductively Coupled Plasma (ICP) reactor in order to deposit silicon dioxide thin films using silane and nitrous oxide [10]. In this study, different oxynitride films were deposited in the same equipment at room temperature through the chemical reaction of silane, nitrogen and nitrous oxide (N 2 O). 2. Experimental An industrial, horizontal LPCVD furnace was adapted to work as an ICP-CVD reactor. The silicon oxynitride films were deposited using constant flows of 3 sccm silane (SiH 4 ) and of 6 sccm nitrogen and a variable nitrous oxide (N 2 O) flow ranging from 3 to 9 sccm, upon (100), 75 mm diameter, p type, silicon wafers with resistivities in the range of 1 – 20 V cm. The 0040-6090/$ - see front matter D 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.tsf.2005.12.186 * Corresponding author. Tel.: +55 11 3322 2217; fax: +55 11 3315 0383. E-mail addresses: zambom@lsi.usp.br (L.S. Zambom), patrick@lsi.usp.br (P. Verdonck). 1 Present address: IMEC, Belgium. Thin Solid Films 515 (2006) 596 – 598 www.elsevier.com/locate/tsf