| AVS 60th International Symposium and Exhibition | |
| Thin Film | Tuesday Sessions |
| Session TF-TuM |
| Session: | ALD for Emerging Applications |
| Presenter: | A.J.M. Mackus, Eindhoven University of Technology, Netherlands |
| Authors: | A.J.M. Mackus, Eindhoven University of Technology, Netherlands D. Garcia-Alonso, Eindhoven University of Technology, Netherlands H.C.M. Knoops, Eindhoven University of Technology, Netherlands A.A. Bol, Eindhoven University of Technology, Netherlands W.M.M. Kessels, Eindhoven University of Technology, Netherlands |
| Correspondent: | Click to Email |
The material Pt has many applications because of its catalytic activity, chemical stability, and high work function. Several Pt ALD processes have been reported for substrate temperatures in the range 100-300 °C. For certain applications involving temperature-sensitive materials such as polymers, fibers, and biological samples, it is valuable to have processes available for Pt ALD at lower substrate temperatures.
In this work, the temperature window for ALD of low-resistivity Pt has been extended to room temperature by the development of new plasma-assisted ALD processes. During thermal ALD of Pt from MeCpPtMe3 and O2 gas, the ligands of the precursor undergo dehydrogenation reactions on the catalytic Pt surface, which leads to a carbonaceous layer that poisons the surface inhibiting further surface reactions.1 Combustion of this carbonaceous layer during the ALD cycle requires a substrate temperature above 200 °C, or alternatively, the use of strong oxidizing agents such as ozone or oxygen plasma. However, these strong oxidizing agents oxidize the deposited Pt to PtO2 when the deposition is carried out at low substrate temperatures. The deposition of Pt at low temperatures can be achieved by adding a H2 gas or H2 plasma exposure step to the ALD cycle in which the PtO2 at the surface is reduced to metallic Pt in every cycle.2,3
High-quality, virtually pure films with a resistivity of 18−24 μΩcm were obtained for the three-step ALD processes consisting of MeCpPtMe3 dosing, O2 plasma exposure, and H2 gas or H2 plasma exposure.3 The reaction mechanism of these processes was investigated by gas-phase Fourier transform infrared spectroscopy (FT-IR). It will be shown that the newly developed processes enable the deposition of Pt on polymer, textile, and paper surfaces. The ability to coat temperature-sensitive substrates significantly broadens the application range of Pt ALD.
1. Mackus et al., Chem. Mater. 24, 1752 (2012)
2. Hämäläinen et al., Thin Solid Films 513, 243 (2013)
3. Mackus et al., Chem. Mater., online early access; DOI: 10.1021/cm400274n