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DS: Fachverband Dünne Schichten

DS 16: Functional Oxides

DS 16.2: Vortrag

Dienstag, 26. Februar 2008, 17:30–17:45, H 2032

Switching and microstructural characterization of a Pt/TiO₂/Pt capacitor stack as nonvolatile ReRAM — •Herbert Schroeder, Jun Miao, and Doo Seok Jeong — IEM im Institut für Festkörperforschung und CNI, Forschungszentrum Jülich GmbH, D-52425 Jülich

Switchable resistors are discussed as nonvolatile resistive memory (NV-ReRAM) devices for future ultra-large scale-integrated memory chips in cross-bar architecture because of their simple geometry. A large variety of candidates is presently under discussion including paraelectric oxides. We have produced metal/insulator/metal (MIM) capacitor stacks with thin TiO₂ films between platinum electrodes and investigated the electrical and microstructural properties. As they are highly insulating they have to be electroformed to show the desired memory switching. In this contribution detailed experimental data on electrical and microstructural characterization are presented in order to demonstrate correlations and conclude on mechanisms controlling the forming and the switching. Besides ex-situ, sequential investigations also first results on in-situ experiments in electron microscopes are reported, i.e. the electrical current/voltage was applied during observation in a SEM and TEM. Main results are: a) Both memory switching modes, the symmetrical unipolar switching and the asymmetrical bipolar switching have been observed dependent on the forming sequence. b) Using very thin, electron transparent top electrodes (10-30 nm) and thin TiO₂ film (27nm) we could observe localized structural changes dependent on the forming sequence and the polarity of the forming.