Excimer laser recrystallization of selectively floating a-Si thin film

Abstract We report a new excimer laser annealing (ELA) method which increases the grain size of poly-Si film considerably by employing a selectively floating a-Si active layer structure. An air-gap, with low thermal conductivity, blocks the heat conduction to the underlying substrate in the floating a-Si region so that the lateral temperature gradient, which is responsible for a lateral grain growth, is successfully induced by the proposed simple air-gap structure. Our experimental result shows that large grains were grown in the lateral direction from the edge to the center of the floating active region. The large lateral grains exceeding 4 μm were successfully obtained with only one laser irradiation and uniform lateral grains have been grown with a wide laser annealing process window.