Method of fabricating a bit line of flash memory

摘要

A method of fabricating a bit line of a flash memory. A silicon-on-insulator (SOI) has a buried oxide layer therein and a silicon layer thereon. A patterned hard mask layer is formed on the silicon layer. The exposed silicon layer and the buried oxide layer thereunder are removed to form a bit line opening while using the hard mask layer as a mask. A conformal lightly doped polysilicon layer is formed over the substrate. A heavily doped polysilicon layer is formed over the substrate and filling the bit line opening. The lightly doped polysilicon layer and the heavily doped polysilicon layer are removed until arriving at the silicon layer to form a bit line. The hard mask layer is then removed.