Ultra-thin elevated channel poly-Si TFT technology for fully-integrated AMLCD system on glass

Abstract

A novel low temperature poly-Si (LTPS) TFT technology called the ultra-thin elevated channel TFT (UT-ECTFT) technology is proposed. The devices fabricated using this technology have an ultra-thin channel region (300 /spl Aring/) and a thick drain/source region (3000 /spl Aring/). The ultra-thin channel region is connected to the heavily doped thick drain/source region through a lightly doped overlapped region. The ultra-thin channel region is used to obtain a low grain-boundary trap density in the channel, and the overlapped lightly doped region provides an effective way for electric field spreading at the drain, thereby reducing the electric field there significantly. With the low grain-boundary trap density and low drain electric field, excellent current saturation characteristics and high drain breakdown voltage are obtained in the UT-ECTFT. Moreover, this technology provides complementary LTPS TFT's with more than two times increase in on-current and 3.5 times reduction in off-current compared to conventional thick channel LTPS TFT's.