1. Investigation of hafnium-aluminate alloys in view of integration as interpoly dielectrics of future Flash memories
- Author
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Molas, Gabriel, Bocquet, Marc, Buckley, Julien, Grampeix, Helen, Gély, Marc, Colonna, Jean-Philippe, Licitra, Christophe, Rochat, Névine, Veyront, Thomas, Garros, Xavier, Martin, François, Brianceau, Pierre, Vidal, Vincent, Bongiorno, Cosimo, Lombardo, Salvatore, Salvo, Barbara De, and Deleonibus, Simon
- Subjects
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FLASH memory , *DIELECTRICS , *HIGH voltages , *ELECTRIC fields - Abstract
Abstract: In this paper, we evaluate the potentialities of hafnium-aluminates (HfAlO) materials as possible candidates for the interpoly dielectrics of future Flash memory devices. HfAlO layers of different thicknesses and compositions are integrated in single-layers and in Oxide/HfAlO/Oxide (OHO) triple-layer stacks, and analyzed in terms of coupling and insulating capabilities. We demonstrate that increasing the Hf content allows reducing the leakage current at high voltages but it results in a stronger leakage current at low voltages. We also show that once normalized in electric fields, the leakage current characteristics are independent of the high-k thickness. The electron conduction modes in these materials, at different temperatures, are also investigated. The activation energy increases with the Hf concentration in the HfAlO alloy, resulting in a higher leakage current at elevated temperatures. Finally, it is demonstrated that the conduction in triple-layer stacks is limited by a Poole–Frenkel conduction in the high-k layers, while the trap contribution in the case of single-layers becomes dominant when the HfAlO layer is thicker than 8nm. [Copyright &y& Elsevier]
- Published
- 2007
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