Investigation of the Corrosion Behavior of Atomic Layer Deposited Al2O3/TiO2 Nanolaminate Thin Films on Copper in 0.1 M NaCl

Abstract

Fifty nanometers of Al2O3 and TiO2 nanolaminate thin films deposited by atomic layer deposition (ALD) were investigated for protection of copper in 0.1 M NaCl using electrochemical techniques. Coated samples showed increases in polarization resistance over uncoated copper, up to 12 MΩ-cm2, as measured by impedance spectroscopy. Over a 72-h immersion period, impedance of the titania-heavy films was found to be the most stable, as the alumina films experienced degradation after less than 24 h, regardless of the presence of dissolved oxygen. A film comprised of alternating Al2O3 and TiO2 layers of 5 nm each (referenced as ATx5), was determined to be the best corrosion barrier of the films tested based on impedance spectroscopy measurements over 72 h and equivalent circuit modeling. Dissolved oxygen had a minimal effect on ALD film stability, and increasing the deposition temperature from 150 °C to 250 °C, although useful for increasing film quality, was found to be counterproductive for long-term corrosion protection. Implications of ALD film aging and copper-based surface film formation during immersion and testing are also discussed briefly. The results presented here demonstrate the potential for ultra-thin corrosion barrier coatings, especially for high aspect ratios and component interiors, for which ALD is uniquely suited.

Bayesian Machine Learning for Efficient Minimization of Defects in ALD Passivation Layers

“…In the literature, different corrosion current densities were reported. 31 , 89 , 90 For example, corrosion current densities of 8.3×10 –7 A cm –2 and 3×10 –8 A cm –2 were found for 29 nm thick Al 2 O 3 films on copper by Daubert et al and Chai et al, respectively. 36 , 38 Indeed, Mirhashemihaghighi et al .…”

Preventing Corrosion of Aluminum Metal with Nanometer-Thick Films of Al2O3 Capped with TiO2 for Ultraviolet Plasmonics

“…Larger thicknesses could further improve the corrosion resistance as it was previously reported in the context of flat metal surfaces. 52,55,57,58 However, thicknesses above 15 nm are not appropriate for plasmonic applications which require nanoscale features and short distances to the metal film so as to maximize the electromagnetic field enhancement. 1 On the lower side, we found that a 5 nm thickness did not provide a sufficient improvement in the photocorrosion protection.…”

“…Atomic layer deposition (ALD) and plasmaenhanced chemical vapor deposition (PECVD) of thin inert layers of metal oxides offer powerful alternative approaches for corrosion protection owing to their ability to deposit dense layers of oxide materials with controlled nanometer thickness and conformal coating at the nanoscale. 50 Alumina (Al2O3), [51][52][53] titania (TiO2) [54][55][56] and hafnia (HfO2) 57,58 are commonly used to protect flat metal surfaces.…”

Experimental investigation of the effect of processing parameters on densification, microstructure and hardness of selective laser melted 7075 aluminium alloy

“…Some of these properties include high electrical and thermal conductivity and high reflectivity [1,2]. Aluminum owes high corrosion resistance because of the tenacious oxide film (Al 2 O 3 ) which occurs naturally on its surface [3][4][5]. Due to high reflectivity and thermal conductivity, aluminum requires high laser power to melt [6,7].…”