A novel omega-shaped-gated polycrystalline-silicon thin-film transistor (TFT) silicon-oxide-nitride-oxide-silicon (SONOS) nonvolatile memory with field-enhanced nanowire (FEN) structure has been proposed to improve the program and erase (P/E) performance. Each nanowire inherently had twin sharp corners fabricated simply by sidewall spacer formation to obtain high local electric fields. The field-enhanced carrier tunneling via such a structure led to faster P/E speed and wider memory window for the Ω-Gate SONOS as compared to the conventional planar (CP) counterpart. Such an Ω-Gate-TFT SONOS memory using simple process is very suitable for future system-on-panel applications.

In this letter, gate-all-around (GAA) polycrystalline silicon thin-film transistors (TFTs) with self-aligned grain-growth channels were fabricated using excimer laser crystallization (ELC) on a recessed-nanowire (RN) structure. Via the RN structure constructed by a simple sidewall-spacer formation, location-controlled nucleation and volume-confined lateral grain growth within the RN body during ELC process have been demonstrated with only one perpendicular grain boundary in each nanowire channel. Because of the high-crystallinity channel together with GAA operation mode, the proposed GAA-RN TFTs show good device integrity of lower threshold voltage, steeper subthreshold slope, and higher field-effect mobility as compared with the conventional planar counterparts.