Atomic Layer Deposition on Polymer Thin Films: On the Role of Precursor Infiltration and Reactivity
| Autor: | Babs Van de Voorde, Philippe Smet, Sandra Van Vlierberghe, Jin Li, Christophe Detavernier, Robin Petit |
|---|---|
| Rok vydání: | 2021 |
| Předmět: |
chemistry.chemical_classification
Materials science Polymer Barrier layer Chemistry chemistry.chemical_compound Atomic layer deposition Physics and Astronomy chemistry X-ray photoelectron spectroscopy Chemical engineering General Materials Science Polystyrene Fourier transform infrared spectroscopy Thin film Layer (electronics) |
| Zdroj: | AVS ALD/ALE 2022, Abstracts |
| ISSN: | 1944-8252 |
| Popis: | Polymers play a role in a variety of applications owing to their flexibility, low toxicity and ease of processing. In many cases (e.g., lighting, photovoltaics, displays), they are incorporated into devices as host materials for electro-optical components (e.g., quantum dots), which are sensitive to the environment, i.e., moisture, oxygen and temperature. Polymers do not provide adequate protection, apparent from their high water vapor and oxygen transmission rates. To improve the stability, they are coated with barrier layers. We report on the use of Al2O3 ALD, with TMA and H2O, to coat polymer thin films: polystyrene (PS), poly(methyl methacrylate) (PMMA) and poly(ethylene terephthalate glycol) (PET-G) [1]. Polymers being complex molecular networks encompassing a free volume, this free volume causes a growth delay during Al2O3 ALD on polymers, calling for an understanding of the nucleation, precursor infiltration and polymer relaxation effects that impact this growth delay. Here, the reactivity of the polymers towards TMA is investigated with FTIR and XPS, while the extent of TMA infiltration as a function of deposition temperature is probed with in situ ellipsometry (SE). Our results show that the temperature and presence, location and amount of polymer functional groups (C-O, C=O) influence the growth delay. While PS showed no infiltration, TMA-induced swelling was observed for PMMA and PET-G, with a change in reversibility as a function of temperature (Fig. 1). At low temperatures, TMA mainly physisorbs, while a pericyclic reaction drives the interaction with TMA for PMMA and PET-G at elevated temperatures (Fig. 2). For PET-G, this reaction can result in chain scission, accounting for the significant TMA infiltration. Furthermore, SE is used to determine the moment of closed layer formation, halting the infiltration and indicating the onset of linear growth (Fig. 3). The better understanding of the influence of the ALD deposition conditions and polymer properties on the barrier growth enablesfaster, more effective barrier creation for other ALD-polymer combinations. |
| Databáze: | OpenAIRE |
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