Characteristics of poly-Si TFT combined with nonvolatile SONOS memory and nanowire channels structure

Abstract

In this work, we study a polycrystalline silicon thin-film transistor (poly-Si TFT) combined with a silicon-oxide-nitride-oxide-silicon (SONOS) stack gate dielectric and nanowire channels structure for the applications of transistor and nonvolatile memory. The proposed device named with NW SONOS-TFT has superior electrical characteristics of transistor and also can exhibit high program/erase (P/E) efficiency under adequate bias operation. The V-th decreases from 2.45 V to 1.76 V and subthreshold swing reduces from 0.57 V/decade to 0.42 V/decade. The programming V-th shift is improved from 2.2 V to 3.3 V at 14 V for 1 s and the erasing V-th shift is improved from -0.3 V to -1.3 V at -14 V for 1 s. The dramatic improvement can be attributed to the tri-gate structure and corner effect. In addition, the memory device has a promising data retention behavior at 85 degrees C and a 0.8 V memory window after 5 x 10(3) P/E cycles operations. Hence, the NW SONOS-TFT is suitable for application in the future system-on-panel display. (C) 2007 Elsevier B.V. All rights reserved.