Xenon Flash Lamp Annealing of Poly-Si Thin Films

We have investigated xenon (Xe) flash lamp annealing for the crystallization of amorphous silicon (a-Si) films for polycrystalline silicon (poly-Si) thin film transistors on glass substrates. The Xe flash lamp emits white light with a wavelength range of for , thereby instantaneously supplying the energy necessary to crystallize a-Si films to poly-Si films. The distance between electrodes in the lamp is , the bore diameter is , and the peak voltage is up to . The sample structure is a-Si deposited on a glass substrate by plasma-enhanced chemical vapor deposition using gas. An average grain size of is obtained without substrate heating during Xe flash lamp annealing when the light energy density is . The grain size is less than at , and a significant grain growth occurs at . The light energy is absorbed by the whole film, because the Xe flash lamp emits light with a wide wavelength range of . Therefore, when the light energy exceeds its threshold at which the a-Si film melting point is observed, films can be partially melted and subsequently crystallized at the top and bottom surfaces, thereby forming large-grain poly-Si.