| 摘要 |
PURPOSE:To implement high breakdown strength in a memory cell and reduction in area of the cell, by forming three diffusion layers by using two kinds and one kind of impurities. CONSTITUTION:A gate electrode 8 comprising a polysilicon film doped with phosphorus is formed on a silicon oxide film 7, which is to become a gate insulating film. Then, phosphorus ions are implanted before silicon films 9 and 10 are formed by the oxidation of a substrate 1. An N-type diffusion layer 4 is formed between the channel regions of an MOSFET and an MNOSFET. A silicon nitride film 11 is formed on the films 9 and 10. The gate electrode 12, which is formed by phosphorus doping, is overlapped on the electrode 8 on the film 11. Then phosphorus ions are implanted by a self-aligning technology with the gate electrode as a mask, and N-type diffusion layers 2 and 5 are formed. N-type diffusion layers 3 and 6 are formed from above the layers 2 and 5 using arsenic. Thus the double-layer diffusion layers mode of the arsenic and the phosphorus are formed. |
