SEMICONDUCTOR DEVICE HAVING DOUBLE ISOLATION STRUCTURE AND MANUFACTURING METHOD THEREOF

摘要

PURPOSE: A semiconductor device having a double isolation structure and a method for manufacturing the same are provided to be capable of obtaining good device isolation and small device isolation area. CONSTITUTION: The first conductive type epitaxial layer(56) is formed on a semiconductor substrate(50). A device region is composed of the substrate and the epitaxial layer. A double diffused MOS transistor is formed in the device region. A device isolation structure(90) for defining the device region has a double isolation structure of a diffused isolation layer(63) and a trench isolation layer(64). The diffused isolation layer(63) is formed in the substrate for surrounding the base and bottom sidewall of the device region. The trench isolation layer(64) is surrounded to the upper sidewall of the device region via the epitaxial layer(56).