Batch-processing of high performance amorphous-silicon/silicon-nitride thin-film transistors (for active-matrix addressable LCD)

The low-temperature chemical-vapor-deposition (CVD) method has been applied to the batch process of amorphous-silicon/silicon-nitride thin-film transistors (a-Si/SiN TFTs). The high-performance a-Si/SiN TFTs (mobility >1 cm/sup 2//Vs, threshold voltage <7 V, and subthreshold voltage-swing <1.5 V/decade) have been fabricated with good reproducibility and uniformity over a wide range of CVD conditions. This feature makes the a-Si/SiN TFT batch-process practical. The films have the unique feature that their electronic properties change slightly within a wide range of CVD conditions. Thus, the CVD system can be optimized by adjusting the wall temperature to achieve the identical deposition rate along the gas flow. Then, uniform TFT characteristics can be obtained over large and stacked substrate surfaces.<>