Analysis of Al2O3 Atomic Layer Deposition on ZrO2 Nanoparticles in a Rotary Reactor

Abstract

AbstractAl2O3 atomic layer deposition (ALD) is analyzed on ZrO2 nanoparticles in a rotary reactor. This rotary reactor allows for static exposures and efficiently utilizes the reactants for ALD on high surface area nanoparticles. The Al2O3 ALD is performed using exposures to Al(CH3)3 and H2O reactants. The pressure transients during these exposures are examined using a sequence of reactant micropulses. These micropulses are less than the required exposures for the ALD surface chemistry to reach completion. The pressure transients during identical sequential Al(CH3)3 and H2O micropulses change as the surface chemistry progresses to completion. These pressure transients allow the required saturation reactant exposure to be determined to maximize reactant usage. The ZrO2 nanoparticles are coated using various numbers of Al(CH3)3 and H2O reactant exposures. The Al2O3 ALD‐coated ZrO2 nanoparticles are subsequently analyzed using a number of techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), Auger electron spectroscopy (AES), scanning AES (SAES), and X‐ray photoelectron spectroscopy (XPS). The TEM images reveal very conformal Al2O3 ALD on the ZrO2 nanoparticles. The Al2O3 ALD thicknesses versus number of Al(CH3)3 and H2O reactant exposures yielded an Al2O3 ALD growth rate of 2.0 Å per reactant cycle. The AES and XPS results are consistent with an Al2O3 ALD film that completely and conformally covered the underlying ZrO2 nanoparticle. The SAES measurements show that the Al2O3 ALD films are continuous and homogeneous on the ZrO2 nanoparticles. These results demonstrate that a rotary reactor can successfully perform ALD with high reactant efficiency on high surface area nanoparticles.