Improved Poly-Si TFTs with a lightly Doped Drain Structure Using an Ion Doping Process

Abstract

Using only one doping process, the LDD structures with good TFT characteristics have been successfully fabricated. In this process, non-mass-separated ion doping method which is a very effective technology for the large area doping is used. Because it has a broad depth profile of phosphorus concentration within the offset SiO_2 region and poly-Si region, the feature is very useful for controlling the TFT characteristics. The LDD TFTs show high ON/OFF ratio of more than 10^8 and no degradation of ON current.