METHOD FOR MANUFACTURING SEMICONDUCTOR DEVICE

摘要

PURPOSE: A method for manufacturing semiconductor device is provided to reduce the step of a manufacturing process by forming the threshold voltage control region not only in the trench type isolating structure of an n-MOS region but also in the trench type isolating structure of a p-MOS region without mask. CONSTITUTION: A pad oxide film(2) and a nitride film(3) are deposited on a substrate(1) in turns. A portion of the nitride film(3) and the pad oxide film(2) is etched to expose a portion of the substrate(1). A trench is formed by etching the exposed substrate(1). A threshold voltage control region(4) is formed in the side of the trench by using the remains of the nitride film(3) as mask. An oxide film is deposited on the whole structure, flattened. The exposed nitride film(3) and the pad oxide film(2) are removed, so that an isolating structure is formed in the trench. An n-MOS transistor is formed on an n-MOS transistor region(NA) and a p-MOS transistor is formed on a p-MOS transistor region(PA).