INOR 351 |
| Atomic layer deposition (ALD) is an important future film growth technique for microelectronics and other applications, but this area is presently limited by the small number of available chemical precursors. The growth of thin films by ALD requires precursors that are thermally stable at the substrate temperature, to avoid loss of the surface limited growth mechanism through uncontrolled precursor decomposition. In addition to thermal stability, ALD precursors should be highly reactive toward a second reagent to afford the desired thin film material. This combination of high thermal stability and high reactivity toward a second reagent can be difficult to achieve, especially in metalorganic precursors that do not contain halogen atoms. Herein, we describe a series of pyrazolate-based precursors that exhibit very high thermal stability and high reactivity toward oxygen reactants, as well as ALD growth studies from these precursors. The precursor tert-butylimidotris(3,5-di-tert-butylpyrazolato)tantalum has been employed with ozone as a coreactant for the ALD growth of high quality tantalum(V) oxide thin films. Remarkably, this tantalum precursor exhibits a temperature region of surface limited growth (“ALD window”) between 325 and 450 °C, which demonstrates that the pyrazolate ligand imparts very high thermal stability to this precursor. The characterization of the tantalum(V) oxide films will be overviewed. We will also describe the very high thermal stability of bis(tris(3,5-dimethylpyrazolyl)borate)barium, and will present preliminary BaTiO3 ALD thin film growth studies using this precursor, a titanium precursor, and water. The combined results suggest that pyrazolate-based ligands should be very useful for the preparation of new ALD precursors. |
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Thin Films: Chemical Vapor Deposition and Atomic Layer Deposition
8:30 AM-12:10 PM, Monday, August 20, 2007 BCEC -- 258C, Oral
Division of Inorganic Chemistry |