25.3: A Novel Self-Aligned Coplanar Amorphous Silicon Thin Film Transistor

A novel self-aligned coplanar a-Si:H TFT was developed using the three stacked layers of thin a-Si: H, silicon-nitride (SiNx), and a-Si:H. After patterning thin a-Si:H and SiNx, the structure was ion-doped and then Ni layer was deposited. The fabricated TFT exhibited a field effect mobility of 0.44 cm2/Vs, a threshold voltage of 5.3 V, a subthreshold slope of 0.5 V/dec., an on/off current ratio of about 107, and parasitic resistance of 5.3 × 103 Ω Coplanar self-aligned a-Si:H TFT is very suitable for the fabrication of large area and high resolution TFT-LCD because of small parasitic resistance and very small parasitic capacitance between gate and source/drain electrodes.