Uniform lanthanum oxide atomic layer deposition using ozone

This study investigated the problem of lanthanum oxide uniform growth by atomic layer deposition (ALD) using water as the oxygen reagent. Although water is the classic reagent for ALD, it can be the reason for some problems (e.g., nonuniformity) with hygroscopic oxides (such as lanthanum oxide). There are some ways to improve coating quality: increase the purge duration after the water pulse, increase the synthesis temperature with the water process, and replace the oxygen reagent (e.g., for ozone). In this work, ways to improve were studied in the processes of coating growth using La(iPrCp)3. Spectral ellipsometry was used to study the thickness of the coatings. X-ray photoelectron spectroscopy with argon ion etching was used to investigate the chemical composition. X-ray diffraction and x-ray reflectometry were used to define structural properties. The influence of the purge duration after water and the reactor temperature was defined. The ALD parameters of La(iPrCp)3 and ozone were investigated. The dependence of coating characterization on oxygen reagent was researched. No improvements in uniformity were found in the synthesis using water; at the same time, the positive effect of ozone on the coating uniformity was confirmed. Ozone as a replacement for water helps to increase the uniformity of the coating by about 10 times. Coatings obtained with ozone are more similar to lanthanum oxide, and those obtained with water are more similar to lanthanum hydroxide.