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Akira OTAKE Keita YAMAGUCHI Katsumasa KAMIYA Yasuteru SHIGETA Kenji SHIRAISHI
Due to the aggressive scaling of non-volatile memories, “charge-trap memories” such as MONOS-type memories become one of the most important targets. One of the merits of such MONOS-type memories is that they can trap charges inside atomic-scale defect sites in SiN layers. At the same time, however, charge traps with atomistic scale tend to induce additional large structural changes. Hydrogen has attracted a great attention as an important heteroatom in MONOS-type memories. We theoretically investigate the basic characteristics of hydrogen-defects in SiN layer in MONOS-type memories on the basis of the first-principles calculations. We find that SiN structures with a hydrogen impurity tend to reveal reversible structural change during program/erase operation.
Doo-Hyun KIM Il Han PARK Seongjae CHO Jong Duk LEE Hyungcheol SHIN Byung-Gook PARK
This paper presents a detailed study of the retention characteristics in scaled multi-bit SONOS flash memories. By calculating the oxide field and tunneling currents, we evaluate the charge trapping mechanism. We calculate transient retention dynamics with the ONO fields, trapped charge, and tunneling currents. All the parameters were obtained by physics-based equations and without any fitting parameters or optimization steps. The results can be used with nanoscale nonvolatile memory. This modeling accounts for the VT shift as a function of trapped charge density, time, silicon fin thickness and type of trapped charge, and can be used for optimizing the ONO geometry and parameters for maximum performance.