A viscous Ni solution was applied on amorphous Si films and its effect on the crystallization of amorphous Si films was investigated. A viscous Ni solution was prepared by dissolving NiCl2 in 1 N HCl and mixing it with propylene glycol. NiCl2 and Ni was uniformly deposited by spin coating and drying the viscous metal solution, and it enhanced the crystallization at lower temperature overcoming the nonuniform coating of diluted acid metal solution. The a-Si films deposited by low pressure chemical vapor deposition with Si2H6 were fully crystallized in 10 h at 500 degreesC by furnace annealing and in 8 h at 480 degreesC by microwave annealing. The enhanced crystallization was due to the mediation by NiSi2. The surface roughness of the crystallized Si films using the Ni solution was smoother than that of the crystallized Si films with Ni metal layer.