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Svärd L, Putkonen M, Kenttä E, Sajavaara T, Krahl F, Karppinen M, Van de Kerckhove K, Detavernier C, Simell P. Low-Temperature Molecular Layer Deposition Using Monofunctional Aromatic Precursors and Ozone-Based Ring-Opening Reactions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:9657-9665. [PMID: 28838240 DOI: 10.1021/acs.langmuir.7b02456] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Molecular layer deposition (MLD) is an increasingly used deposition technique for producing thin coatings consisting of purely organic or hybrid inorganic-organic materials. When organic materials are prepared, low deposition temperatures are often required to avoid decomposition, thus causing problems with low vapor pressure precursors. Monofunctional compounds have higher vapor pressures than traditional bi- or trifunctional MLD precursors, but do not offer the required functional groups for continuing the MLD growth in subsequent deposition cycles. In this study, we have used high vapor pressure monofunctional aromatic precursors in combination with ozone-triggered ring-opening reactions to achieve sustained sequential growth. MLD depositions were carried out by using three different aromatic precursors in an ABC sequence, namely with TMA + phenol + O3, TMA + 3-(trifluoromethyl)phenol + O3, and TMA + 2-fluoro-4-(trifluoromethyl)benzaldehyde + O3. Furthermore, the effect of hydrogen peroxide as a fourth step was evaluated for all studied processes resulting in a four-precursor ABCD sequence. According to the characterization results by ellipsometry, infrared spectroscopy, and X-ray reflectivity, self-limiting MLD processes could be obtained between 75 and 150 °C with each of the three aromatic precursors. In all cases, the GPC (growth per cycle) decreased with increasing temperature. In situ infrared spectroscopy indicated that ring-opening reactions occurred in each ABC sequence. Compositional analysis using time-of-flight elastic recoil detection indicated that fluorine could be incorporated into the film when 3-(trifluoromethyl)phenol and 2-fluoro-4-(trifluoromethyl)benzaldehyde were used as precursors.
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Affiliation(s)
- Laura Svärd
- VTT Technical Research Centre of Finland , P.O. Box 1000, FI-02044 VTT, Espoo, Finland
| | - Matti Putkonen
- VTT Technical Research Centre of Finland , P.O. Box 1000, FI-02044 VTT, Espoo, Finland
| | - Eija Kenttä
- VTT Technical Research Centre of Finland , P.O. Box 1000, FI-02044 VTT, Espoo, Finland
| | - Timo Sajavaara
- Department of Physics, University of Jyväskylä , P.O. Box 35, FI-40014, Jyvaskyla, Finland
| | - Fabian Krahl
- Department of Chemistry, School of Chemical Technology, Aalto University , P.O. Box 16100 FI-00076 Espoo, Finland
| | - Maarit Karppinen
- Department of Chemistry, School of Chemical Technology, Aalto University , P.O. Box 16100 FI-00076 Espoo, Finland
| | - Kevin Van de Kerckhove
- Department of Solid State Sciences, Ghent University , Krijgslaan 281/S1, Gent B-9000, Belgium
| | - Christophe Detavernier
- Department of Solid State Sciences, Ghent University , Krijgslaan 281/S1, Gent B-9000, Belgium
| | - Pekka Simell
- VTT Technical Research Centre of Finland , P.O. Box 1000, FI-02044 VTT, Espoo, Finland
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