The Study of Channel Doping and Hydrogenation Effects on Polysilicon Thin Film Transistors

• Main Authors: Huang-Wen Tseng, 曾皇文
• Other Authors: Tan-Fu Lei; Chung-Len Lee
• Format: Others
• Language: en_US
• Published: 1993
• Online Access: http://ndltd.ncl.edu.tw/handle/77528471304542503129

碩士 === 國立交通大學 === 電子研究所 === 81 === With regard to the unpassivated poly-Si TFTs with undoped channel, the magnitude of the threshold voltage is greater than 5V and the leakage current is usually not available. Thus the necessary channel doping and hydrogenation are required to reduce threshold voltages to acceptable values. In this thesis , we have studied the characteristics of the p-channel TFTs with boron and arsenic implantation doses before and after hydrogenation. From the experimental results, it is seen that the thicker films of 86nm exhibit the characteristics just as those we have predicted that the threshold voltage increases with the channel arsenic dose and decreases with the channel boron dose for properly channel implantation. However, the thinner films of 26nm show the features of passivation for very lightly channel implantation. In addition, it is seen that the increase of the Source/Drain resistance after hydrogenation becomes more significant as the thickness of the polysilicon is scaled down. Therefore, though the TFT with thinner channel thickness(26nm) exhibits better characteristics, its on current is limited by the drastically increased Source/Drain resistance after hydrogenation. In view of the reason mentioned aboved, it is recommended that the length of Source/Drain region should be decreased in order to minimize the influence of Source/Drain resistance on electrical characteristics.