Regensburg 2000 – wissenschaftliches Programm
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DS: Dünne Schichten
DS 13: Nanostrukturen
DS 13.4: Fachvortrag
Dienstag, 28. März 2000, 15:45–16:00, H31
Sub-100nm ferroelectric memory cells fabricated by SEM- based nano-lithography and characterized by piezoresponse SFM — •Marin Alexe, Catalin Harnagea, Alain Pignolet, Dietrich Hesse, and Ulrich Goesele — Max-Planck-Institut fuer Mikrostrukturphysik, Weinberg 2, D-06120 Halle/Saale
In a prospective 1 Gbit non-volatile ferroelectric memory, the area of the whole memory cell should not exceed 150x150 nm2 and this implies ferroelectric capacitors having lateral dimensions of 100 nm or less. At these nano-size dimensions, finite size effects will induce anomalies of the ferroelectric behavior, the most severe being inhibiting of polarization switching. Ferroelectric memory cells with lateral sizes down to 75 nm were prepared using one of the next generation lithography process derived from SEM, namely electron beam direct writing. Patterns of SBT and PZT cells with lateral dimension down to 100 nm were exposed into a corresponding metalorganic film using a commercial electron-beam lithography system (ELPHY Plus) adapted to a JEOL JSM 6400 scanning electron microscope (SEM) working at 40 kV. Switching of single sub-100 nm cells was achieved and piezoelectric hysteresis loops were recorded using a scanning force microscope working in piezoresponse mode. The piezoelectricity and its hysteresis acquired for 100 nm PZT cells demonstrate the size effects are not fundamentally limiting the density increase of non-volatile ferroelectric memories towards the Gbit range.