STABILITY OF STRUCTURAL DEFECTS OF POLYCRYSTALLINE SILICON GROWN BY RAPID THERMAL ANNEALING OF AMORPHOUS-SILICON FILMS

The crystallization of a-Si films, grown by low-pressure chemical vapo r deposition and annealed by rapid thermal annealing (RTA), at 850 deg rees C in conjunction with conventional heating at 600 degrees C for 6 h, has been studied using transmission electron microscopy. The resul ts of RTA at 850 degrees C showed that the improvement of the poly-Si structure (large crystallites with low density of microtwins) was maxi mized for an annealing time of 150 s. The same results were also obtai ned by RTA at 850 degrees C with successive steps of 30 s duration eac h (5 X 30 s). A multiple-step annealing is sufficient to activate the movement of twin boundaries within the grains resulting in their annih ilation. This process is comparable with the technology of growing goo d-quality poly-Si on low-cost glass substrates.