NITRIDATION FOR SPLIT GATE MULTIPLE VOLTAGE DEVICES

摘要

A method is disclosed for making gate oxides on a silicon wafer surface for multiple voltage applications comprising the steps of growing an oxide layer (12) on a wafer (10) surface, exposing the surface of the oxide layer (12) to a nitrogen ion containing plasma to form a nitrided layer (22). Next, a photoresist layer (14) is deposited over a portion of the oxide layer (12) and the isolation (30), followed by etching of the exposed nitrided layer 22 and a portion of the oxide layer (12) to create a thinner silicon dioxide layer (32). The photoresist layer (14) is removed, the wafer (10) is cleaned and then the thinner silicon dioxide layer (32) is removed prior to a final oxidation step to form a thinner silicon dioxide layer (34) having a different thickness than the silicon dioxide layer (12).