To suppress UV damage on the subthreshold characteristic of TFT during hydrogenation for high density TFT SRAM

In this letter, we find an efficient way to suppress UV damage on the characteristics of polysilicon thin-film transistors (TFTs) during hydrogenation for high density TFT SRAM. Polysilicon TFT can be free from UV damage during hydrogenation if the channel region is shielded by a metal line of the same width as channel. After hydrogenation, the metal shielded TFT shows an excellent subthreshold swing of 112 mV/dec, and the leakage current can be as low as 20 fA while the unshielded TFT shows a subthreshold swing of 220 mV/dec and a leakage current of 0.33 pA. This gives almost 200% improvement in subthreshold swing and one order of magnitude reduction in leakage current.