We present the impact of Al-doped ZnO (AZO) layer of polycrystalline silicon (poly-Si) thin films grown at different annealing temperatures using aluminum-induced crystallization (AIC). In situ observation revealed that the increase of crystallized fraction was fast in poly-Si films grown with AZO layer compared to those without AZO. It is explained that the roughness of interface between Si and Al by introducing AZO layer was increased, which contributes to enhancement of diffused Si concentration into Al layer. Those results were also quantitatively demonstrated by calculating of Si concentration diffused into the Al layer. Therefore, we exhibit that controlling interface roughness is shown to be important to determine the growth rate of poly-Si thin films.