ALD of SiO2 at Room Temperature Using TEOS and H 2 O with NH 3 as the Catalyst

Abstract

Amine catalysts can reduce the high temperatures and long exposure times required for atomic layer deposition (ALD) using and reactants. One problem is that the reaction product, HCl, readily reacts with the amine catalysts to form a salt. Salt formation can be avoided by using organometallic silicon precursors. This study investigated catalyzed ALD on and particles using alternating exposures of tetraethoxysilane (TEOS) and at 300 K with as the catalyst. The sequential surface chemistry was monitored in a vacuum chamber using in situ transmission Fourier transform infrared (FTIR) spectroscopy. Alternating and exposures yielded and surface species, respectively, that sequentially deposited silicon and oxygen. Repetition of the TEOS and exposures in an ABAB… reaction sequence led to the appearance of bulk vibrational modes. The infrared absorbance of these bulk vibrational modes increased with the number of AB reaction cycles. After deposition, the and particles were examined using transmission electron microscopy (TEM). The TEM images revealed extremely uniform and conformal films. The measured film thicknesses were consistent with ALD growth rates of 0.7-0.8 Å per AB reaction cycle. The catalysis mechanism was also explored by monitoring the FTIR spectra of hydroxylated particles vs. pressure at constant temperature and vs. temperature at constant pressure. The spectra revealed strong hydrogen bonding between and surface species that activates the oxygen in for nucleophilic attack. Catalyzed at room temperature should be useful for deposition of inorganic and insulating films on thermally fragile organic, polymeric, or biological substrates. © 2004 The Electrochemical Society. All rights reserved.