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 °C and a 0.8 V memory window after 5 × 10 3 P/E cycles operations. Hence, the NW SONOS-TFT is suitable for application in the future system-on-panel display.