| 摘要 |
PURPOSE:To obtain a semiconductor device which has preferable capacitor characteristic and ultrafine capacitor by forming a high density diffused layer in the impurity density of the prescribed value or higher on the surface of a substrate at the periphery of a groove, and then forming a capacitor oxide film by thermal oxidation. CONSTITUTION:A field oxide film 22 is formed on the surface of a p type Si substrate 21, and a thin thermal oxide film 23 is formed on the substrate 21. Then, an n<+> type diffused layer 25 is formed on the film 23, and a groove is formed by etching the substrate 21 at the center of the layer 25 by an isotropic etching. A phosphosilicate glass film 26 is accumulated on the overall surface, and an n type diffused layer 27 is formed on the inner wall of the groove. Then, the films 23, 26 are removed, a capacitor oxide film 28 is formed by thermal oxidation, polycrystalline Si film is accumulated on the overal surface, and patterned to obtain a capacitor electrode 29. Then, an n<+> type diffused layer 25 of 5X10<20>cm<-3> of impurity density is formed on the substrate 21 to surround the groove. The stepwise difference of the boundary from the groove of the substrate 21 is rounded, thereby causing no concentration of an electric field. |
