Atomic layer deposition of Al2O3 and SiO2 on BN particles using sequentialsurface reactions

Al2O3 and SiO2 were deposited on BN particles with atomic layer control usi ng alternating exposures of Al(CH3)(3)/H2O and SiCl4/H2O, respectively. The sequential surface chemistry was monitored in vacuum using transmission Fo urier transform infrared (FTIR) spectroscopy studies on high surface area B N particles. The initial BN particles displayed vibrational modes consisten t with BOH* and BNH2* surface species. These species reacted with Al(CH3)(3 ) or SiCl4 and were converted to AlCH3* or SiCl* surface species. The subse quent reaction with H2O converted the surface species to AlOH* or SiOH *. B y repeating the sequential surface reactions, the absorbance of Al2O3 and S iO2 bulk vibrational modes on the BN particles increased vs, the number of reaction cycles. Transmission electron microscopy (TEM) studies revealed ex tremely uniform and conformal Al2O3 coatings on the BN particles. X-ray pho toelectron spectroscopy (XPS) analysis was consistent with conformal Al2O3 coatings. In contrast, TEM investigations observed fairly uniform SiO2 coat ings on the edge planes of the BN particles and only patches of SiO2 on the basal planes. XPS measurements were consistent with some uncovered regions on the SiO2-coated BN particles. These results illustrate the capability o f sequential surface reactions to deposit ultrathin Al2O3 and SiO2 films on BN particles. (C) 2000 Elsevier Science B.V. All rights reserved.