AbstractAn improved polysilicon high voltage thin film transistor (HVTFT) structure with field-plate-controlled offset region (FP-HVTFT) is proposed for eliminating the current-pinching phenomena often observed in the conventional offset-gate polysilicon HVTFTs. The new metal field plate serves, in lieu of ion implantation, to control the conductivity of the offset region. By properly biasing the field plate to distribute the drain electric field at both ends of the offset region, high-voltage operation of up to 100 V, suitable for many large-area applications, is achieved. Good turn-on characteristics without current-pinching effects are consistently obtained. Moreover, the new FP-HVTFT also eliminates the lightly-doped-drain implant normally required in conventional offset-gate HVTFTs, resulting in a simpler and more reproducible process flow.
A Low Impact Ionization Rate Poly-Si TFT with a Current and Electric Field Split Design