A method for doping polysilicon improves a doping profile during plasma doping and includes forming a silicon layer using two separate operations. After forming a first silicon layer, thermal annealing is performed to crystallize the first silicon layer, such that the uniformity of a doping concentration according to the depth of a layer inside is improved during plasma doping. Additionally, a doping concentration at the interface between a polysilicon layer and a gate oxide layer is increased. A by-product deposition layer is reduced, which is formed on the surface of a polysilicon layer due to the increase of a doping concentration in a polysilicon layer. As a result, the dopant loss, which is caused by the removing and cleansing of an ion implantation barrier used during doping, is reduced.