Method of forming shallow trench isolation with silicon oxynitride barrier film

Abstract

A method of forming shallow trench isolation in a semiconductor substrate. A hard mask having an opening is formed on the semiconductor substrate. The semiconductor substrate is etched through the opening to form a shallow trench. The semiconductor substrate such as silicon substrate is annealed in an ambient containing nitric oxide or nitrogen and oxygen to form a silicon oxynitride film on the shallow trench to serve as a barrier to prevent dopant source/drain outdiffusion. An insulator is then formed on the hard mask to fill the shallow trench. The insulator is planarized while the hard mask is used as the polishing stop layer. Thereafter, the hard mask is removed to expose the upper surface of the semiconductor substrate and leave a shallow trench isolation.

Dependencies are inferred from the claim text.