Method of annealing polycrystalline silicon using solid-state laser and devices built thereon

Thin-film transistors (TFTs) are used in the construction of active-matrix devices like liquid-crystal displays (LCDs), organic light emitting diode (OLED) displays, and image sensors. TFTs based on amorphous silicon suffer from low operating speed and lack of a p-type device, making it difficult to realize peripheral circuits. There has therefore been a move to polycrystalline silicon devices, which can be obtained from amorphous silicon by furnace or laser-induced heating. This invention introduces a technique of forming polycrystalline silicon thin films by combining the processes of crystallization of amorphous silicon and laser based annealing. The resulting quality of the films is good, uniform and reproducible. Semiconductor devices can be built on the films with a low temperature. As a result, the cost of lasers used in the process is typically low. The resulting polycrystalline silicon can be used in a variety of applications, including but not limited to sensors, electronic devices, flat-panel displays and 3-dimensional integrated circuits (ICs)