Performance of poly-Si TFT using the CW laser lateral crystallization (CLC)

摘要

A new poly-Si TFT technology on a glass substrate has been developed by laser crystallization utilizing a diode pumped solid state (DPSS) CW laser with high power stability. Very large grains, typically 3 μm x 20 μm, are obtained. The grain boundaries are generally parallel to one another and to the scanning direction of the laser beam. No thermal damage was introduced to the glass substrate through the crystallization process. The field effect mobility oj poly-Si TFT was improved as much as 566 cm~2/Vs for n-channel and 200 cm~2/Vs for p-channel. We also investigated the effects of scanning speed on the microstructure of the grain and the characteristics of TFTs. Although the field effect mobility decreases as the increase of scanning speed, the characteristics of TFTs stay comparable to those of excimer laser crystallized poly-Si TFT even at high scanning speed of 200 cm/s.