| 摘要 |
PURPOSE:To improve characteristics and integration density, by forming a guard ring by a self-alignment method with respect to a Schottky barrier part, i.e. a silicide layer. CONSTITUTION:On a P-type silicon substrate 11, an N<+> embedded layer 12 and an N-type epitaxial layer 13 as the first semiconductor layer are formed. Then, a P<-> isolation layer 14, an N<+> diffused layer 15, a thin thermal oxide film 16 and a silicon nitride film 17 are formed. Then, the silicon nitride film 17 and the thermal oxide film 16 are patterned, and a nitride film pattern 17a and a thermal oxide film pattern 16a are formed. Thereafter, boron ions (a) are implanted in the epitaxial layer 13, and a P-type impurity layer 19 is formed. Then a field oxide film 20 is formed by selective oxidation. At the same time, the P-type diffused layer spreads to not only a part directly beneath the field oxide film 20 but also to the surface of the epitaxial layer 13. Thus, a P-type guard ring 21 as the second semiconductor layer is formed. |
