Post-Annealing Effects on a Laterally Grown Polycrystalline Silicon Layer

Abstract

A polysrystalline silicon (poly-Si) layer prepared by selectively enlarging laser crystallization (SELAX) was post-annealed by excimer laser irradiation. The average grain width increased 26% because of partly merged grains, while the morphological trace of the laterally grown poly-Si layer was maintained. The difference in field-effect mobility resulting from thin-film-transistor (TFT) configuration was reduced by post-annealing. The field-effect mobility of TFTs parallel to the lateral growth direction decreased slightly (within 4.5% for n-type and 11.5% for p-type). On the other hand, TFTs configured perpendicular to the lateral growth direction increased as the energy density during post-annealing increased (up to 200% for both types). For n-type TFTs these results were attributed to the increase of the effective width of the grain and the reduction of the density of trapping states at grain boundaries.