Single shot excimer laser annealing of amorphous silicon for AMLCD

We analyse in detail one critical step in the fabrication of high quality polysilicon on low cost glass substrate by spectroscopic ellipsometry (SE). We use the very promising technique of single shot excimer laser annealing (SSELA), which is known now to give very good results in terms of homogeneity, crystallinity and surface roughness. Different starting materials have been used. First UHV-CVD amorphous Si films quasi-free of hydrogen have been treated. We show that one laser shot is sufficient to get completely crystallised films with large crystal size and limited surface roughness if the pulse energy is optimised. When the amorphous silicon films have limited hydrogen content (PECVD at low temperature), we show that the crystallisation can also be achieved after one single laser shot but the morphological quality is improved if a thermal annealing at 400°C is performed before laser annealing.