A low‐cost dehydrogenation system of amorphous silicon thin films used for fabricating low‐temperature polycrystalline silicon

Abstract

Low-temperature polycrystalline silicon thin-film transistors were widely employed in active-matrix flat-panel displays and giant microelectronics. In general, a-Si thin films prepared by plasma-enhanced chemical vapor deposition contain hydrogen. To prevent the ablation caused by sudden hydrogen eruption during excimer laser crystallization (ELC), two dehydrogenation systems are developed in this study to reduce hydrogen content before excimer laser crystallization. One is a ceramic heater-based dehydrogenation system and the other is a quartz tube radiant heaterbased dehydrogenation system. The hydrogenated amorphous silicon (a-Si : H) thin films prepared by plasma-enhanced chemical vapor deposition are dehydrogenated by both systems. Fourier-transform infrared absorption spectra revealed that the hydrogen content reduces after dehydrogenation processing. Raman measurements confirmed that the a-Si : H thin films are still amorphous phase. The major potential advantages of quartz tube radiant heater-based dehydrogenation system include rapid heating speed, good dehydrogenation quality, small footprint and low cost. Twosteps temperature rise method is a good candidate for dehydrogenation processing because it provides sample with low thermal distortion.

Uniform dehydrogenation of amorphous silicon thin films using a wide thermal annealing system

“…Several methods have been proposed for a dehydrogenation process to improve the issues of the conventional thermal annealing methods [7][8][9][10]. There are some required characteristics and performance for high-efficiency dehydrogenation systems, such as low damage to substrate, fast temperature ramping-up, high throughput, and low cost.…”

“…Despite this method decreasing annealing temperature, there are still adverse effects at manufacturing throughput problem because the additional UV illumination process prolongs the total dehydrogenation processing time. In addition, although step-bystep excimer laser annealing is an effective and promising candidate for dehydrogenation method [9]. This method is a cost-ineffective, lower ramping-up speed, and limited extension of the system size due to its small illumination spot.…”