SEMICONDUCTOR DEVICE AND MANUFACTURING METHOD THEREOF

摘要

A semiconductor device and its manufacturing method are provided to simplify manufacturing processes and to economize fabrication costs by forming an aiming transistor without an additional guard ring using an improved first semiconductor region. A first semiconductor region(2) is formed in a semiconductor substrate(1). A second semiconductor region is formed in the substrate. A low critical value type low voltage driver transistor is formed on the substrate. A high critical value type low voltage driver transistor is formed on the first semiconductor region. A low and high critical value type low voltage driver transistor is formed on the second semiconductor region. An isolation layer(4) is formed between the transistors on the substrate. The periphery of the low critical value type low voltage driver transistor is enclosed with the first semiconductor region.