Carboxylic acids as oxygen sources for the atomic layer deposition of high-κ metal oxides

A nonaqueous approach inspired from sol-gel chemistry and adapted to the deposition of metal oxide thin films by atomic layer deposition (ALD) is presented. The process is based on the reaction of a carboxylic acid with a metal alkoxide. Contrary to classical approaches, no oxygen source that could lead to the oxidation of the silicon substrate is required. Instead, a surface esterification reaction is responsible for the film formation. The growth of metal oxides is achieved at temperatures as low as 50 degrees C on various supports including carbon nanotubes, organic fibers, and silicon wafers. The as-grown films show an excellent conformality and possess good dielectric properties due to their high purity. Inherent to the chemical approach is the possibility to grow oxides on silicon while minimizing the formation of a low-kappa interfacial layer.