| 摘要 |
The present invention provides a method for forming an embedded memory MOS. The method involves first forming a first dielectric layer and an undoped polysilicon layer, respectively, on the surface of the semiconductor wafer with a defined memory array area and a periphery circuits region. Then, the undoped polysilicon layer in the memory array area is doped to become a doped polysilicon layer, followed by the formation of a protective layer on the surface of the semiconductor wafer. Thereafter, a first photolithographic and etching process(PEP) is used to etch the protective layer and the doped polysilicon layer in the memory array area to form a plurality of gates, and to form lightly doped drains(LDD) adjacent to each gate. A silicon nitride layer and a second dielectric layer are formed, followed by their removal in the periphery circuits region. Finally, a second PEP is used to etch the undoped polysilicon layer in the periphery circuits region to form a plurality of gates, as well as to form LDDs, spacers and sources/drains(S/D) of each MOS in the periphery circuits region. |
