| 摘要 |
PURPOSE: To increase the capacitor capacitance of a DRAM memory cell. CONSTITUTION: A silicon nitride film 12 whose thickness becomes thinner partially is formed on a polysilicon film 12 which becomes the lower electrode of a capacitor with a natural oxide film 13 in between. The nitride film 14 is thermally oxidized until part 15 of the polysilicon film 12 is oxidized by utilizing the thickness variation of the nitride film 15. Then, after the unoxidized part 14a of the nitride film 14, oxidized part 14b the nitride film 14, natural oxide film 13, and oxidized part of the polysilicon film 15 are removed and a silicon nitride film 16 is formed on the removed surface, and then, a heeling oxide film 17 is formed by thermally oxidizing the surface of the nitride film 16, a polysilicon film 18 which becomes the upper electrode of the capacitor is formed. Therefore, the effective surface areas of the electrodes of the capacitor are increased by the inegulaties formed on the surface of the polysilicon film 12. |
