METHOD FOR MANUFACTURING SEMICONDUCTOR DEVICE WITH GATE OXIDE LAYER OF PLURAL THICKNESS LEVEL

摘要

PURPOSE: A method for manufacturing a semiconductor device is provided to easily obtain a gate oxide layer with plural thickness level by using a simple nitrogen ion-implantation process. CONSTITUTION: A silicon substrate(100) is defined by the first portion(1000) and the second portion(1200). Nitrogen ions are selectively implanted into the second portion of the silicon substrate. By first oxidizing the resultant structure, oxide layers with different thickness are formed on the first and second portion, respectively. An oxide layer of plural thickness level is formed by patterning the oxide layers. By second oxidizing the resultant structure, a gate oxide layer(114) of plural thickness level is formed.