Electrical characteristics of new LDD poly-Si TFT structure tolerant to process misalignment

Abstract

A new lightly doped drain (LDD) poly-Si TFT structure having symmetrical electrical characteristics independent of the process induced misalignment is described in this paper. Based on the experimental results, we have established that there is no difference between the bi-directional I/sub D/-V/sub G/ characteristics, and a low leakage current, comparable to a conventional LDD poly-Si TFT, has been maintained for this new poly-Si TFT. The maximum ON/OFF current ratio of about 1×10/sup 8/ is obtained for the LDD length of 1.0 μm. In addition, the kink effect in the output characteristics has been remarkably improved in the new TFTs in comparison to the conventional non-LDD single- or dual-gate TFTs.