Novel selective process via self-assembled monolayers for pattern growth of carbon nanotubes

Abstract

In this study, a novel IC compatible deposition process to fabricate the CNTs pattern with tunable tube number density was successfully developed by using the liquid chemical technologies of self-assembled monolayers (SAMs) and the Fe-assisted CNTs growth. The tube number density could be controlled by changing the SAMs formation and post processing parameters. The Si wafers with the a:Si/Si3N4 layer patterns were first prepared by low pressure chemical vapor deposition (LPCVD) and lithography techniques to act as the substrates for selective deposition of SAMs. The selectivity of SAMs from APTMS solution (N-(2-aminoethyl)-3-aminopropyltrimethoxsilane) is based on its greater reactivity of head group on a:Si than SO, films. The areas of pattern with SAMs will first chelate the Fe3+ ions by their diamine-terminated group. The Fe3+ ions were then consolidated to become Fe-hydroxides in NaBH, Solution to form the Fe-hydroxides pattern. Finally, the Fe-hydroxides pattern was pretreated in H plasma, and followed by CNTs deposition using Fe as catalyst in a microwave plasma-chemical vapor deposition (MPCVD) system to become the CNTs pattern. The products in each processing step, including SAMs, Fe-hydroxides and CNTs, were characterized by contact angle measurements, scanning electron microscopy (SEM), Raman, XPS and Auger spectroscopy. The results show that the main process parameters include the surface activation process and its atmosphere, consolidation time and temperature, H plasma pretreatment. The function of each processing step will be discussed. (C) 2004 Elsevier B.V. All rights reserved.