Shallow trench isolation structure and method of fabricating the same

A method of fabricating a shallow trench isolation structure, comprising:

• forming a trench in a substrate;
• forming an oxide liner on the sidewalls and bottom of the trench;
• forming a silicon oxynitride layer on the substrate and the sidewalls and bottom of the trench;
• and
• forming an oxide layer on the silicon oxynitride layer and substantially filling the trench by high density plasma chemical vapor deposition (HDPCVD).