Physica E 37 (2007) 11–15 Growth of carbon nanotubes by Fe-catalyzed chemical vapor processes on silicon-based substrates Renato Angelucci a,Ã , Rita Rizzoli a , Vincenzo Vinciguerra b , Maria Fortuna Bevilacqua c , Sergio Guerri a , Franco Corticelli a , Mara Passini a a CNR-IMM Bologna, via Gobetti 101, Bologna 40129, Italy b STMicroelectronics, 10 Science Park Road, #02-08, 117684, Singapore c STMicroelectronics, Piazzale Enrico Fermi 1, Porto del Granatello—Portici, Napoli 80055, Italy Available online 6 October 2006 Abstract In this paper, a site-selective catalytic chemical vapor deposition synthesis of carbon nanotubes on silicon-based substrates has been developed in order to get horizontally oriented nanotubes for field effect transistors and other electronic devices. Properly micro- fabricated silicon oxide and polysilicon structures have been used as substrates. Iron nanoparticles have been obtained both from a thin Fe film evaporated by e-gun and from iron nitrate solutions accurately dispersed on the substrates. Single-walled nanotubes with diameters as small as 1 nm, bridging polysilicon and silicon dioxide ‘‘pillars’’, have been grown. The morphology and structure of CNTs have been characterized by SEM, AFM and Raman spectroscopy. r 2006 Elsevier B.V. All rights reserved. PACS: 81.07.De; 61.46.Fg; 73.63.Fg Keywords: Carbon nanotubes; Catalytic chemical vapor deposition; Iron 1. Introduction Carbon nanotubes (CNTs) [1,2] are novel allotropic 1D (one dimensional) forms of carbon consisting of hollow cylindrical-shaped molecules with graphitized walls that can be considered as molecular nanowires. CNTs have emerged in the field of molecular electronics because of their excellent conducting properties allowing the manufacturing of devices such as FETs (field effect transistors) [3–5] and SETs (single electron transis- tors) [6–8]. A strong key requirement for a successful CNTs integration with silicon is the development of a growth technology compatible with the standard manufacturing processes of the microelectronic industry. Moreover, the ability to grow CNTs with predictable and reproducible properties, i.e. controlling their semiconducting or metallic characteristics, on suitable substrates, at a fixed location and with a desired orientation on surfaces, is still a great challenge for the fabrication of hybrid carbon micro and nanocircuits. This ability, including the control over CNTs diameter and chirality, would allow the exploitation of their unique electrical, thermal and mechanical properties, in a wide range of electronic devices as emitters in flat panel displays, bio and DNA sensors and in the IC thermal management. Considering this scenario, we have developed a site-selective catalytic chemical vapor deposition (CCVD) synthesis of CNTs on silicon-based substrates, which is based on a standard process of the silicon technology, the CVD technique. In this paper, a modified CCVD process, exploiting iron nanoparticles as catalysts, methane as carbon gas feedstock and hydrogen as carrier gas at 900 1C, has been developed in order to get reproducible horizontally oriented nano- tubes for FETs and other electronic devices. Modifications of the CCVD process are necessary in order to switch from multi-walled nanotubes (MWNTs) to single-walled nano- tubes (SWNTs) and from a vertical to a horizontal growth of isolated SWNTs. ARTICLE IN PRESS www.elsevier.com/locate/physe 1386-9477/$ - see front matter r 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.physe.2006.07.043 Ã Corresponding author. Tel.: +39 0516399120; fax: +39 0516399216. E-mail address: angelucci@bo.imm.cnr.it (R. Angelucci).