Crystallization of amorphous silicon films using a multistep thermal annealing process

A multistep thermal annealing method, which utilizes the incubation time for nucleation to form large-grained polycrystals from seeded amorphous silicon film, was studied. According to this method, crystallization takes place in steps, via heating-cooling cycles. In each cycle the water is annealed for a period which is less than the incubation time for nucleation and then cooled to a low temperature for relaxation. During each annealing period, the seed grains grow to a certain extent, while spontaneous nucleation does not occur. Preliminary experimental results obtained with 0.17 μm thick amorphous films, which were deposited by the low pressure chemical vapor deposition method (at 818 K, 400 mTorr) on oxidized silicon substrates, exhibited general agreement with the basic idea of a multistep annealing process.