| AVS 58th Annual International Symposium and Exhibition | |
| In Situ Spectroscopy and Microscopy Focus Topic | Monday Sessions |
| Session IS+AS+SS-MoA |
| Session: | In Situ Characterization of Solids: Film Growth, Defects, and Interfaces |
| Presenter: | Ivo Erkens, Eindhoven University of Technology, Netherlands |
| Authors: | I.J.M. Erkens, Eindhoven University of Technology, Netherlands A.J.M. Mackus, Eindhoven University of Technology, Netherlands H.C.M. Knoops, Eindhoven University of Technology, Netherlands F. Roozeboom, Eindhoven University of Technology, Netherlands W.M.M. Kessels, Eindhoven University of Technology, Netherlands |
| Correspondent: | Click to Email |
Atomic layer deposition (ALD) of noble metals and noble metal oxides on high-aspect-ratio 3D nanostructures has a wide variety of potential applications in sensing and catalysis. Despite several studies,1-3 much is still unknown about the reaction mechanism of Pt ALD using (MeCp)PtMe3 and O2, which can be considered a model system for noble metal ALD processes. Questions remain regarding the surface species and reactions, and the temperature dependence of the growth per cycle (GPC). In this contribution we expand the understanding of the Pt ALD mechanism by combining quadrupole mass spectrometry (QMS) and spectroscopic ellipsometry (SE). Using these in-situ techniques to study the process as a function of temperature between 100 and 300°C, we have gained a unique perspective, which has led to several new insights. The time-resolved QMS data for CH4 and CO2 show that combustion and other ligand reactions at the surface occur in sequence, while competing for the available carbon atoms. Quantification of the data showed that approximately 80% of the C atoms are combusted during the O2 pulse. By performing the QMS measurements in a temperature series, valuable information was obtained on the rate of combustion of the hydrocarbon ligands at the Pt surface during the O2 pulse. Using a combination of QMS and SE data, we were able to formulate a mechanism explaining growth inhibition at low temperatures. This mechanism manifests itself through three temperature dependent growth regimes: no growth below 100°C; limited growth between 100 and 250°C; and full growth between 250 and 300°C. Using results from surface science literature a likely explanation for these regimes was given. This involves the cyclopentadienyl ligands at the Pt surface forming reactive intermediates or being thermally decomposed. The mechanism was corroborated by QMS and SE data on post-plasma treatment cycles, by which catalytic activity was temporarily restored. We were therefore able to link the temperature dependence of the GPC to combustion kinetics. A detailed description of our methods and results will be given in our contribution.
1. Aaltonen et al., Electrochem. Solid-State Lett. 6, C130 (2003).
2. Kessels et al., Appl. Phys. Lett. 95, 013114 (2009).
3. Setthapun et al., J. Phys. Chem. C 114, 9758 (2010).