Electrochemical and Surface Analysis of the Corrosion Protection of Copper by Nanometer-Thick Alumina Coatings Prepared by Atomic Layer Deposition. Issue 8 (1st January 2015)

• Record Type: Journal Article
• Authors: Mirhashemihaghighi, Shadi; Światowska, Jolanta; Maurice, Vincent; Seyeux, Antoine; Klein, Lorena H.; Härkönen, Emma; Ritala, Mikko; Marcus, Philippe
• Is Part Of: Journal of the Electrochemical Society. Volume 162:Issue 8(2015)
• Page Start: C377
• Page End: C384
• Publication Date: 2015-01-01
• Subjects: ALD -- Alumina -- Copper -- Corrosion protection -- EIS -- LSV -- Surface analysis -- Ultrathin coatings; Electrochemistry -- Periodicals; 541.3705
• DOI: 10.1149/2.0081508jes
• Languages: English
• ISSNs: 0013-4651

Abstract

Abstract : Corrosion protection by ultra-thin (≤ 50 nm) alumina films deposited by atomic layer deposition (ALD) on copper at 250°C was studied in 0.5 M NaCl aqueous solution by combining electrochemical and surface analytical methods. Time-of-Flight Secondary Ion Mass Spectrometry revealed a homogenous in-depth stoichiometry of the alumina coatings and their residual bulk contamination by organic and water precursor fragments. Trace contamination by a spurious Cu oxide was evidenced at the interface with the Cu substrate despite a reducing pre-treatment. Atomic force microscopy images revealed conformal substrate coverage and a granular-like coating morphology at the nanometer scale. Linear Sweep Voltammetry (LSV) and Electrochemical Impedance Spectroscopy (EIS) showed no electrochemical activity of the coating and a corrosion decrease reaching 4 orders of magnitude for coated samples in comparison with bare copper. Uncoated surface fraction was quantified by application of three different methods using the LSV and EIS data which led to results in excellent agreement. The uncoated surface fraction for 50 nm Al2 O3 layers was ∼0.01%, confirming ALD alumina as an excellent coating for corrosion protection with spectacularly low residual corrosion activity restricted to the bottom of channel defects connecting the substrate to environment through the coating.