Gate-all-around polycrystalline-silicon thin-film transistors with self-aligned grain-growth nanowire channels

Abstract

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.