DUAL GATE OXIDE OF A SEMICONDUCTOR DEVICE AND FORMING THEREOF

摘要

PURPOSE: A method for fabricating a dual gate insulating layer is to prevent an impurity ion implanted into a silicon substrate from being penetrated into a gate insulating layer. CONSTITUTION: A field insulating layer(22) is formed on a silicon substrate(21) with a low voltage region(L) and a high voltage region(H) formed thereon. The first oxide layer(23) is formed on the field insulating layer and the silicon substrate by a thermal process. A nitride layer(24) is formed on the first oxide layer at a thickness of 50 to 80 angstroms. A photoresist is formed on the nitride layer of the low voltage region. The nitride layer formed on the high voltage region is anisotropy etched by using the photoresist as a mask. The second oxide layer(26) is formed on the entire structure by a thermal process. Thereby, the second oxide layer is formed on the high voltage region at a thickness of 300 to 400 angstroms, and on the low voltage region at a thickness of 30 angstroms.