title: High-performance bottom-gate poly-Si polysilicon-oxide-nitride-oxide-silicon thin film transistors crystallized by excimer laser irradiation for two-bit nonvolatile memory applications.
abstract: High-performance bottom-gate (BG) poly-Si polysilicon-oxide-nitride-oxide-silicon (SONOS) TFTs with single grain boundary perpendicular to the channel direction have been demonstrated via simple excimer-laser-crystallization (ELC) method. Under an appropriate laser irradiation energy density, the silicon grain growth started from the thicker sidewalls intrinsically caused by the bottom-gate structure and impinged in the center of the channel. Therefore, the proposed ELC BG SONOS TFTs exhibited superior transistor characteristics than the conventional solid-phase-crystallized ones, such as higher field effect mobility of 393 cm2/V-s and steeper subthreshold swing of 0.296 V/dec. Due to the high field effect mobility, the electron velocity, impact ionization, and conduction current density could be enhanced effectively, thus improving the memory performance. Based on this mobility-enhanced scheme, the proposed ELC BG SONOS TFTs exhibited better performance in terms of relatively large memory window, high program/erase speed, long retention time, and 2-bit operation. Such an ELC BG SONOS TFT with single-grain boundary in the channel is compatible with the conventional a-Si TFT process and therefore very promising for the embedded memory in the system-on-panel applications.
authors.affiliation: Department of Electronics Engineering and Institute of Electronics, National Chiao Tung University, Hsinchu 30010, Taiwan.
authors.forename: I-Che
authors.initials: IC
authors.lastname: Lee
authors.forename: Hsu-Hang
authors.initials: HH
authors.lastname: Kuo
authors.forename: Chun-Chien
authors.initials: CC
authors.lastname: Tsai
authors.forename: Chao-Lung
authors.initials: CL
authors.lastname: Wang
authors.forename: Po-Yu
authors.initials: PY
authors.lastname: Yang
authors.forename: Jyh-Liang
authors.initials: JL
authors.lastname: Wang
authors.forename: Huang-Chung
authors.initials: HC
authors.lastname: Cheng