| 摘要 |
PURPOSE:To contrive to improve the yield and to reduce the cost by a method wherein a conductive impurity to form an isolation layer is selectively implanted to the bottom of a groove by the use of a mask provided to form the groove, and is then diffused. CONSTITUTION:A material, where an n<-> type Si epitaxial layer 12 has been formed on a P<-> type Si semiconductor substrate 10, and an n<+> type buried layer 14 between the layer and the substrate, is used as the semiconductor base body. A thick oxide film mask 20 is formed on the surface of the layer 12, and grooves 22 running along isolation regions a3 are formed by etching treatment. A thin oxide film 24 is formed on the inside surface of the groove 22, and a p type conductive impurity 26 is selectively implanted from above only to the bottom of the groove. The impurity left only at the bottom of the groove is thermally diffused and thus forms an n type diffused layer 29 and a p<+> type isolation layer 30. The process of heat treatment can be reduced by thermal diffusion of the diffused layer 29 and the isolation layer at the same time. |
