Patent ID: 6521549
Filing Date: 2003-02-18
Classification: H01L

Abstract:
A method of forming a relatively thin gate insulator of a digital switching transistor in a first region of a silicon substrate for an integrated circuit and a relatively thick gate insulator of an analog linear transistor in a second region of the silicon substrate, comprising the steps of:implanting nitrogen atoms in the first region; oxidizing the first and second regions of the silicon substrate to form a silicon oxynitride layer and an outer layer of silicon dioxide as a part of the silicon oxynitride layer in the first region and a layer of silicon dioxide in the second region; removing the outer layer of silicon dioxide from the silicon oxynitride layer to leave a remaining layer of substantially-only silicon oxynitride and removing an upper portion of the layer of silicon dioxide in the second region; and using the remaining layer of substantially-only silicon oxynitride to form the gate insulator of the digital switching transistor.