Solid phase post-treatment of polysilicon films by a continuous argon laser

This paper presents an alternative to the solid phase crystallization in a furnace and the liquid phase crystallization by a laser irradiation. Conventional annealing in a furnace leads to a uniform, but defected grain size distribution. Laser crystallization induces an inhomogeneous grain size distribution but with nearly no defects. Thus, an alternative is proposed using both furnace and laser crystallization. The silicon layers are crystallized by solid phase crystallization and then post-annealed using a cheap continuous wave argon laser. By using a low energy, in order to stay in the solid phase during the irradiation, the homogeneous grain size distribution, resulting from the furnace annealing is preserved. The laser irradiation aims to reduce the in-grain defects. Thin film transistors realized in this way present a field effect mobility of 145 cm2/V·s with a dispersion smaller than 10%.