High‐Performance Polycrystalline Silicon Thin‐Film Transistors without Source/Drain Doping by Utilizing Anisotropic Conductivity of Bridged‐Grain Lines

Abstract

AbstractBy utilizing anisotropic conductivity of bridged‐grain (BG) lines, a polycrystalline silicon (poly‐Si) thin‐film transistor (TFT) without source/drain (S/D) doping is designed, simulated, and fabricated. In the new design, the current is made to flow along the BG lines in the S/D region and flow perpendicularly to the BG lines in the channel. By taking advantage of the anisotropic conductivity of the BG lines, the S/D doping process is eliminated and the fabrication process cost is reduced. Meanwhile, the advantages of adopting BG lines are maintained. The as‐fabricated TFTs without S/D doping exhibit excellent device characteristics, compared with normal TFTs. The reliability of TFTs without S/D doping is also evaluated under hot carrier stress and negative/positive bias stress. Additionally, the proposed new TFT structure allows a wider range of dopant activation conditions.