Method for forming enhanced FOX region of low voltage device in high voltage process

摘要

A method for forming enhanced field oxide (FOX) region of low voltage devices in a high voltage process is disclosed. The method includes providing a semiconductor structure comprising a substrate, two field oxide regions on the substrate, a well between the two field oxide regions in the substrate and a silicon nitride layer between the two field oxide regions above the well. As a key step, nitrogen is implanted into the semiconductor structure, and the silicon nitride layer is then removed. Then, a gate oxide layer on the well and silicon oxynitride layer on the field oxide regions are all formed in-situ.