INFLUENCE OF H2-, O2- AND Ar-PLASMA ON THIN Al2O3-FILMS A.Quade, C.Eggs*, H.Wulff, M.Schmidt** E.-M.-A.-University, Institute of Physical Chemistry, 17489 Greifswald, Germany * E.-M.-A.-University, Department of Physics ,17489 Greifswald, Germany **E.-M.-A.-University, Institute of Low-Temperature Plasma Physics, 17489 Greifswald, Germany
We have investigated the influence of H2-, O2- and Ar-plasma on the formation and stability of alumina layers on aluminium. The Al-films were deposited on smooth Si (100) wafer. The thickness of the films varies between 20 and 65 nm. An alumina layer of about 2 nm grew on the surface of the Al-films by atmospheric corrosion.
The thin films were treated in a plasma of a HF-discharge (100 kHz, 100 W) with a gas pressure of 1 mbar and a flow rate of 5 sccm.
The layers were investigated with grazing incidence x-ray reflectometry (GIXR) before and after plasma treatment. XPS and AFM were used additionally to get information about the chemical composition and the structure of the surface.
As a result of the H2-treatment we found an increase of the thickness of the whole film of about 10 nm. The O2-treatment showed only a small increase of the thickness, while Ar-plasma had no influence of the thickness.
In order to fit the reflectometry measurements best results were obtained under the assumption of a multilayer system of [[gamma]]-Al2O3, Al and [[gamma]]-Al2O3.
The O2- and Ar-plasma treatment causes a smoothing of the surface of the layers and their interfaces, while in contrast H2-plasma causes a strong increase of the roughness of the layer. XPS-investigations show that the surface of films only consists of Al2O3. The AFM-measurements corroborate the influence of the different plasma on the surface roughness.