Fabrication and Characterization of Schottky Barrier Polysilicon Thin-Film Transistors

• Main Authors: Ruo Gu Huang, 黃若谷
• Other Authors: Tiao-Yuan Huang
• Format: Others
• Language: en_US
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/46332416298206563760

碩士 === 國立交通大學 === 電子工程系 === 89 === In this thesis, we have proposed and demonstrated a novel poly-Si Schottky barrier thin-film transistor (SB-TFT) with field induced drain (FID). The FID SB-TFT features Co-silicided source/drain and a metal field-plate (i.e., sub-gate) lying over the passivation oxide. It depicts superior ambipolar operation capability by simply switching the bias polarity on the main-gate and the sub-gate. So depending on the polarity of the field-plate bias, the device can be set for n- and p-channel operations with positive and negative field-plate biases, respectively. Excellent on/off current ratios over 106 have been achieved for both n- and p-channel operations if proper bias conditions are chosen. In addition, the GIDL (gate-induced drain leakage)-like off-state leakage current encountered in devices with conventional SB-TFT could be completely suppressed. In this work, we also carried out further study on characterizing the off-state leakage of the devices at different temperatures. For the device with conventional structure, the field emission and thermionic emission from the drain are presumably the primary conduction mechanisms of off-state leakage Under the condition when the field strength is weak, the thermionic emission would dominate the conduction. When the field strength increases, the field emission will become significant. On the other hand, when FID scheme is implemented, the FID would drag the high-field region in the channel away from the drain side. As a result, thermionic emission would be the major conduction mechanism in the off state. In addition to superior electrical characteristics, the FID SB-TFT also features simpler and cheaper fabrication processing, making it very promising for CMOS integration and future large-area electronic applications.