A viscous Ni solution was coated over amorphous Si thin film for evenly spread of Ni metal source. The Ni s. prepared by dissolving $NiCl_2$ into IN HCI and mixing with propylene glycol. $NiCl_2$ and Ni were deposited on the amorphous film after oven dry and they enabled to obtain a uniform crystallization. The crystallization using the viscous Ni solution was a Ni-silicide mediated process, the same process used with Ni metal layer. The crystallization temperature was lowered to $480^{circ}C$ by the synergy effect of silicide-mediated crystallization and microwave-induced crystallization. Lateral crystallization was also enhanced such that the velocity of lateral crystallization by microwave annealing became faster than by furnace annealing.