Growth mode during initial stage of chemical vapor deposition Yuya Kajikawa * , Suguru Noda Department of Chemical System Engineering, Institute of Engineering Innovation, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan Received 6 September 2004; received in revised form 13 October 2004; accepted 15 October 2004 Available online 23 November 2004 Abstract The initial stage during vapor deposition has been extensively studied in physical vapor deposition (PVD) processes, and nucleation theories have been successfully used to model island nucleation processes during PVD. Compared with the extensive research in PVD, there has been less work on understanding the initial stage in chemical vapor deposition (CVD) processes, despite the technological and commercial importance of CVD-based manufacturing systems. In this work we briefly review the nucleation theories developed for PVD processes and consider the validity of them for modeling the initial stage of CVD processes. One characteristic of CVD processes is the existence of an incubation time. Recent research indicates that the incubation time can be caused by the different reactivity of precursors nucleating on substrates and islands. We proposed process indices to evaluate the relative importance of sticking probabilities and desorption of adsorbates on the incubation time. The differing precursor reactivity between islands and substrates may also affect the island growth mode. This situation in CVD processes differs from that in PVD processes, for which current nucleation theories were developed, and therefore prevents the direct application of PVD nucleation theories to CVD processes. Therefore, to model CVD processes, a nucleation model is needed that is sensitive to the different reactivity of precursors to islands and substrates. # 2004 Elsevier B.V. All rights reserved. Keywords: Chemical vapor deposition; Physical vapor deposition; Growth mode; Nucleation; Nanoparticle 1. Introduction Due to its importance in thin-film processing, the initial stage of film deposition and the associated nano-sized islands spontaneously formed during this stage have been extensively studied. This is partly because the continuous reduction of device size makes it important to understand the formation processes of increasingly smaller features, and also because nano- sized islands have interesting physico-chemical properties. The structure of islands can be represented by one of three types of growth modes: two- dimensional (2D) layer mode (Frank–van-der-Merwe, F–M mode), three-dimensional (3D) island mode (Volmer–Weber, V–W mode), and 2D layer followed by 3D island mode (Stranski–Krastanov, S–K mode) www.elsevier.com/locate/apsusc Applied Surface Science 245 (2005) 281–289 * Corresponding author. Tel.: +81 358417672; fax: +81 358417672. E-mail address: kaji@biz-model.t.u-tokyo.ac.jp(Y. Kajikawa). 0169-4332/$ – see front matter # 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.apsusc.2004.10.021