SEMICONDUCTOR DEVICE AND MANUFACTURING METHOD THEREOF

摘要

PURPOSE: A method for manufacturing a semiconductor device is provided to guarantee reliability, by forming metal oxide semiconductor(MOS) transistors on a semiconductor substrate wherein the MOS transistors have gate oxidation layers of the same thickness and different operating voltages. CONSTITUTION: A field oxidation layer is formed between a first operating voltage region and a second operating voltage region of a semiconductor substrate to isolate the first and second operating voltage regions from each other wherein a second operating voltage is higher than a first operating voltage. Gate oxidation layers having the same thickness are formed on the first and second operating voltage regions. A high-density polysilicon gate electrode for a metal oxide semiconductor(MOS) transistor having the first operating voltage is formed on the gate oxidation layer in the first operating voltage region. And, a low-density polysilicon gate electrode for a MOS transistor having the second operating voltage is formed on the gate oxidation layer in the second operating voltage region.