A method and a wafer processing furnace for forming a doped polysilicon layer on a plurality of substrates is provided. In a preferred embodiment, the method comprises providing a plurality of substrates to a process chamber. It also comprises executing a deposition cycle comprising providing a silicon-containing precursor to the process chamber thereby depositing, on the plurality of substrates, an undoped silicon layer until a pre-determined thickness is reached and providing the process chamber with a flow of a dopant precursor gas without providing the silicon-containing precursor to the process chamber. The method also comprises performing a heat treatment process, thereby forming the doped polysilicon layer.