METHOD FOR FORMING SEPARATIVE REGION OF LDMOS TRANSISTOR

PURPOSE: A method for forming a separative region of an LDMOS(Lateral Double diffused MOS) transistor is provided to improve reliability and productivity by simplifying a fabricating process of an isolation region. CONSTITUTION: A p-type epitaxial layer(23) is formed on an upper portion of an insulating oxide layer(22) of a semiconductor substrate(21). A high voltage transistor region is defined by forming a p-type well(24) and an n-type drift(25) on an upper portion of the p-type epitaxial layer(23). A trench structure is formed on an edge of high voltage transistor region. An oxide layer(26) is grown on a wall side of the trench structure. An oxide layer(27) and a polysilicon(28) are deposited on an upper portion of the semiconductor substrate(21). An oxide layer(29) is deposited on a surface of the whole structure. A photo-resist is coated thereon. The photo-resist is formed partially on the oxide layer(29) by performing an exposure process and a development process. The remaining oxide layer(29) is etched by performing a wet etch process.