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Kikuo ONO Takashi SUZUKI Hiroki SAKUTA Kenichi ONISAWA Minoru HIROSHIMA Tooru SASAKI Makoto TSUMURA Nobutake KONISHI
Amorphous silicon thin film transistors(a-Si TFTs) with a channel-etched structure were fabricated. The key technologies to realize these simple-process TFTs were 1) fabricating data lines and pixel electrodes of indium tin oxide(ITO); 2) carrying out tapered dry etching of plural layers of the a-Si and gate insulator silicon nitide; and 3) forming silicide layer to reduce the contact resistance between the phosphorousdoped a-Si and ITO. Excellent image quality, with a high contrast ratio of more than 100: 1, was obtained for video graphic array(VGA) mode TFT-LCDs using a dot inversion driving method. Furthermore, the transmission distribution was uniform with less than a 4.5% deviation on the whole display area although the ITO data line resistances were as large as 120 kΩ per line.
Kikuo ONO Takeshi TANAKA Jun OHIDA Junichi OHWADA Nobutake KONISHI
Transmittance distribution along a horizontal line in LCDs addressed by amorphous silicon TFTs was investigated using measurements and calculations. Nonuniformity of the distribution, in which the transmittance increased with increasing distance from the left edge of the LCD, was observed in a 10 inch diagonal TFT-LCD. The cause of the nonuniformity was attributed to the decrease in voltage drop due to the gate source parasitic capacitance and the increase in gate voltage fall time due to large line resistance, based on the measurements of voltage drops in TFT test elements and calculations considering the decrease in voltage drop. The distribution could be improved by reducing the line resistance and parasitic capacitance in the actual LCD.