Method of LTPS TFT with fin-like structure and its channel self-selective enhanced crystallization

摘要

Forming high-quality Si film on glass with low cost has become one of key challenges in making high performance low temperature poly-Si TFT (LTPS) for future SOG applications. A new method of applying a finlike channel structure into the LTPS TFT is proposed. During the simple ELC process, the geometry size difference between the source/drain (S/D) and the channel region produces a new effect of self-selective enhanced crystallization on the fin-like channel. Via this effect, a high quality poly-Si with larger grain, smoother surface and more compact grain arrangement is achieved. Meanwhile, just like its precursor the SOI FinFET, the fin-like LTPS TFT structure demonstrates a sharp subthreshold slope, and higher transconductance and short channel effect immunity than the conventional thin film device. This was confirmed by ISE simulation.