Fabricating low contact resistance conductive layer in semiconductor device

A conductive layer may be fabricated on a semiconductor substrate by loading a silicon substrate in to a chamber whose inside temperature is at a loading temperature in the range of approximately 250° C. to approximately 300° C., increasing the inside temperature of the chamber from the loading temperature to a process temperature, and sequentially stacking a single crystalline silicon layer and a polycrystalline silicon layer over the silicon substrate by supplying a silicon source gas and an impurity source gas in to the chamber, where the chamber may be, for example, a CVD chamber or a LPCVD chamber.