X-ray reflectance and infrared spectroscopy study of plasma enhanced atomic layer deposited Al2O3 and SiO2

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Journal Title
Journal ISSN
Volume Title
Sähkötekniikan korkeakoulu | Master's thesis
Date
2017-05-08
Department
Major/Subject
Micro- and Nanosciences
Mcode
ELEC3037
Degree programme
NanoRad - Master’s Programme in Nano and Radio Sciences (TS2013)
Language
en
Pages
47+5
Series
Abstract
In this thesis, Al2O3 and SiO2 thin films produced by plasma enhanced atomic layer deposition were studied using X-ray reflectance (XRR) and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). Structural characterization of thin films such as thickness, roughness and density was obtained with the XRR technique. Qualitative chemical constitution of the samples was studied with infrared spectra. The samples were deposited using different plasma powers at low temperature ALD. The characteristic difference between as-deposited vs. 400 celsius annealed Al2O3 thin films were investigated. In case of SiO2, the effect of plasma time and ALD cycle number to thin film properties were analyzed. It was found that thickness does not show any dependence on plasma power, but density is increasing with plasma power for Al2O3, while for SiO2 no apparent dependence was revealed. Analysis of roughness showed that it increases with plasma power for Al2O3 and thin SiO2 samples, while for thicker SiO2 samples it does not change significantly. Analysis of ATR-FTIR spectra showed that there was no significant thin film composition dependence on the different plasma powers. ATR-FTIR results revealed that the structure of Al2O3 includes stretching and bending modes of Al-O bonds and also have sharp valley of Si-O bond due to the presence of native oxide between the Al2O3 thin film and Si substrate. SiO2 infrared spectra comprises Si-O bending and stretching bands and also bands connected with the presence of O-H groups. Also detectable traces of CH3 impurities was found, especially in case of thicker SiO2 thin films. On the basis of the performed analysis the dependence of SiO2 and Al2O3 thin film density, roughness, thickness and molecular constitution on plasma parameters was reported.
Description
Supervisor
Lipsanen, Harri
Thesis advisor
Sippola, Perttu
Keywords
PEALD, Al2O3, SiO2, oxide thin films, XRR, FTIR, O2 plasma
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