Method for moat nitride pull back for shallow trench isolation

This invention relates generally to the field of integrated circuit fabrication, and more particularly to a method for moat nitride pull back for shallow trench isolation. A method of fabricating a shallow trench isolation structure includes forming outwardly of a semiconductor layer a first oxide layer. A nitride layer is formed outwardly of the first oxide layer. A second oxide layer is formed outwardly of the nitride layer. A trench is formed through the first oxide layer, the nitride layer, and the second oxide layer and into the semiconductor layer. With the second oxide layer protecting an upper surface of the nitride layer, the nitride layer is etched to form a lateral recessed side boundary of the trench at the nitride layer. The shallow trench isolation layer is formed in the trench.