Patent ID: 6759302
Filing Date: 2004-07-06
Classification: H01L,Y10S

Abstract:
A method of forming three gate oxide layers with three different oxide thicknesses on a substrate, comprising:(a) providing a substrate with isolation regions and three active areas where circuits are to be formed, said active areas are separated by said isolation regions; (b) growing a first oxide layer on said substrate in the three active areas, said first oxide layer has a first oxide thickness; (c) removing the first oxide layer from two of the active areas; (d) growing a second oxide layer on said substrate wherein said second oxide layer has a second oxide thickness on the two active areas without said first oxide layer and wherein said second oxide layer increases the first oxide thickness on the first oxide layer and the first oxide thickness is greater than the second oxide thickness; and (e) nitridating the second oxide layer with a second oxide thickness in one active area to form a third oxide layer with a third oxide thickness which is less than the second oxide thickness.