Atomic layer deposition of Al2O3 and HfO2 for high power laser application

Abstract

Atomic layer deposition has promising application in optical coatings because of the self-terminating feature. An ideally self-terminating ALD process is based on the saturate chemi-sorption and complete purging of the desorbed precursor molecules. The kinetics of adsorption and desorption are analyzed, providing instruction for the development of ALD process. The exposure length is related to the partial pressure and molecule mass, while the purging length is dependent on the physi-sorption potential energy and substrate temperature. The GPC versus pulse length of ALD Al2O3 and HfO2 are measured. With a set of properly selected parameters, film layers with distinctive self-terminating feature are obtained. A coating consisting of several nanolaminates is analyzed with TEM to study the ALD film structure. An anti-reflection coating is deposited, controlling the film thickness by counting the cycles. The laser resistance of the ALD Al2O3 film, HfO2 film and anti-reflection coating is studied. The results certify the analysis and indicate a promising application in developing a self-terminating ALD process for a new material on a new plant.