Hamburg 2001 – scientific programme

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DF: Dielektrische Festkörper

DF 7: Ferroelektrische Schichten, Nanostrukturen und Keramiken

DF 7.1: Invited Talk

Thursday, March 29, 2001, 09:30–10:10, S18/19

Nano-Engineering of Ferroelectric Thin Films and Mesoscopic Devices — •Marin Alexe, H.N. Lee, C. Harnagea, A. Visinoiu, A. Pignolet, D. Hesse, and U. Gösele — Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120 Halle

In a future 1 Gbit non-volatile ferroelectric memory, the lateral area of the whole memory cell should not exceed 150x150 nm². This implies ferroelectric capacitors having lateral dimensions of 100 nm or less. Consequently, two main problems arise: i) finite size effects will induce anomalies of the ferroelectric behavior, the most critical being the possible inhibiting of polarization switching, and ii) in the case of classical top-down patterning via etching, as the device sizes approach the grain size, device made from polycrystalline films will be highly non-uniform in all parameters. We have addressed both problems, the first one by fabrication of ferroelectric memory cells with lateral sizes down to 75 nm using electron beam direct writing. Switching of single sub-100 nm cells and recording of piezoelectric hysteresis loops was achieved using a scanning force microscope working in piezoresponse mode. It was demonstrated that the finite size effects are not fundamentally limiting the increase of density for non-volatile ferroelectric memories in the Gbit range. The second problem was addressed by growing high quality non-c-oriented epitaxial SrBi₂Ta₂O₉ (SBT) films with (116) and (103) orientations were grown on Si(100) substrates using pulsed laser deposition. Structural investigations, macroscopic, and microscopic electrical measurements will be presented.