Al 2 O 3 thin films: relation between structural evolution, mechanical properties and stability

TL;DRAbstract

In this thesis the relation between structure evolution, mechanical properties, and stability was investigated for Al2O3 thin films. The existence of different polymorphs of this material offers a range of properties for applications, but also meets the process control challenges when the formation of phase pure material is desired. The aim of this work is to affect the phase structure evolution and the stability of vapor deposited alumina thin films, especially for the case of PECVD. This goal is achieved by experimental investigations of the PECVD process which show that the alpha-Al2O3 phase is obtained only at conditions with a low precursor ratio, a long pulse length and a high power density. These allow for more efficient precursor dissociation as suggested from plasma OES data as well as larger ion bombardment. When these conditions are not fulfilled, only gamma-Al2O3 or alpha-gamma-mixture is formed. Due to the use of chloridic precursor, it is found that less Cl content is inc

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