Improvement of oxidation resistance of copper by atomic layer deposition

Al2O3 films were deposited by the atomic layer deposition (ALD) technique onto pure copper at temperatures in the range 100–200 °C. The chemical composition, microstructure, and mechanic properties of the ALD-deposited Al2O3 films were systematically analyzed. The variations in the film characteristics with substrate temperature were observed. Oxidation trials revealed that 20-nm-thick Al2O3 films deposited at a substrate temperature as low as 100 °C suppress oxidative attack on pure copper. The Al2O3 films also showed excellent durability of adhesion strength, according to predictions using the Coffin–Manson model based on the results of accelerated temperature cycling tests. These features indicate that ALD-deposited Al2O3 film is a very promising candidate to be a protective coating for pure copper.