Low-temperature thermal and plasma-enhanced atomic layer deposition of metal oxide thin films
Atomic layer deposition (ALD) is a method for thin ﬁlm fabrication with atomic level precision. This thesis focuses on low-temperature thermal and plasma- enhanced ALD and presents results on thin ﬁlm growth by these techniques with examples of common ALD materials: Al2O3, ZnO and TiO2. As an example of limitations of the thermal ALD the nucleation and growth of Al2O3 and ZnO ﬁlms on different grades of poly(methyl methacrylate) (PMMA) are presented, showing that the initiation of the growth is strongly dependent on both the deposited material and the substrate. A potential application of the ALD ZnO ﬁlms in polymer surface functionalization is demonstrated by changing in the surface wettability by means of UV-illumination. To overcome the nucleation delay in thermal ALD, room-temperature PEALD of ZnO ﬁlms was demonstrated. It is shown that the growth and properties of the ﬁlms depend on the PEALD reactor conﬁguration and the plasma conditions therein. The plasma species interactions shown to be beneﬁcial to the ﬁlm growth were observed to damage the polymer substrates, the severeness depending on the polymer material. The last part of this thesis describes plasma mode transitions in capacitively- and inductively-coupled plasmas, that are typically used in PEALD processing. In addition to the mode transition induced changes in the plasma parameters, the contribution of the different plasma species to the growth and properties of ZnO and TiO2 ﬁlms are demonstrated and discussed. ...
PublisherUniversity of Jyväskylä
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- Väitöskirjat