Corrosion Protection of Copper Using Al₂O₃, TiO₂, ZnO, HfO₂, and ZrO₂ Atomic Layer Deposition

Abstract

Atomic layer deposition (ALD) is a viable means to add corrosion protection to copper metal. Ultrathin films of AlO, TiO, ZnO, HfO, and ZrO were deposited on copper metal using ALD, and their corrosion protection properties were measured using electrochemical impedance spectroscopy (EIS) and linear sweep voltammetry (LSV). Analysis of ∼50 nm thick films of each metal oxide demonstrated low electrochemical porosity and provided enhanced corrosion protection from aqueous NaCl solution. The surface pretreatment and roughness was found to affect the extent of the corrosion protection. Films of AlO or HfO provided the highest level of initial corrosion protection, but films of HfO exhibited the best coating quality after extended exposure. This is the first reported instance of using ultrathin films of HfO or ZrO produced with ALD for corrosion protection, and both are promising materials for corrosion protection.

Thin-Film Engineering of Mechanical Fragmentation Properties of Atomic-Layer-Deposited Metal Oxides

“…The pinhole-free nature of Al 2 O 3 , ZrO 2 , and TiO 2 ALD coatings-and especially their multilayer combinations-are interesting for these applications [1][2][3][4][5][6]. Thin films of Y 2 O 3 are considered to be a promising corrosion-resistant and protective coating for deposition chambers and other three-dimensional metal parts in the semiconductor industry [7]; high temperatures are often involved with semiconductor processing, and hence management of temperature-induced stresses is of high importance [8][9][10][11]. Earth-abundant semiconductors ZnO and Al/ZnO are interesting for flexible electronics, where materials have to be mechanically compatible with roll-to-roll processing and flexing in the end applications; flexible thin-film transistors have been demonstrated with ALD-fabricated layers as both the channel and the dielectric materials [12,13].…”

Ultra-Long-Term Reliable Encapsulation Using an Atomic Layer Deposited HfO2/Al2O3/HfO2 Triple-Interlayer for Biomedical Implants

“…For example, single-layered 20 nm ALD Al 2 O 3 possesses superior WVTR in the order of 10 −3 g•m −2 •day −1 in a few days [25]. However, Al 2 O 3 easily dissolves through hydrolysis when directly exposed to aqueous solutions [17,[25][26][27][28]. Researchers show that the Al 2 O 3 is a good moisture barrier for up to 24 h at room temperature, however this layer later deteriorates as it starts to dissolve in solutions [25,27].…”

Accelerated Hermeticity Testing of Biocompatible Moisture Barriers Used for the Encapsulation of Implantable Medical Devices

“…Although ALD Al 2 O 3 is a good barrier against water vapor, ions, and other gases, direct contact with aqueous solutions results in degradation due to hydrolysis [23][24][25]. To avoid the hydrolysis of Al 2 O 3 in aqueous solutions, capping the Al 2 O 3 layer with more chemically stable oxides, such as SiO 2 or HfO 2 , has been reported [24,26].…”

“…Porosity inspection of the ALD Al 2 O 3 by Cu electroplating or Cu wet etching are practical methods to evaluate the quality of the ALD layers [18]. Monitoring the changes in the thickness or roughness of the ALD Al 2 O 3 layer when the layer is soaked in an aqueous environment enables us to study the dissolution of Al 2 O 3 [23,25]. However, all the approaches above do not show how long the ALD Al 2 O 3 can perform as a good diffusion barrier when soaked in aqueous solution.…”