Method to form shallow trench isolations

A method of forming trenches for shallow trench isolation structures in an integrated circuit device comprising:

• providing a semiconductor substrate;
• forming a pad oxide layer overlying said semiconductor substrate;
• depositing a silicon nitride layer overlying said pad oxide layer;
• depositing a protective layer overlying said silicon nitride layer wherein said protective layer comprises SiOxNy (stoichiometric silicon oxynitride);
• patterning said protective layer, said silicon nitride layer, and said pad oxide layer to expose said semiconductor substrate where trenches for shallow trench isolations are planned;
• and
• etching said semiconductor substrate to complete said trenches in the manufacture of the integrated circuit device wherein the presence of said protective layer prevents loss of said silicon nitride layer during said etching.

A method of forming shallow trench isolations in an integrated circuit device comprising:

• providing a semiconductor substrate;
• forming a pad oxide layer overlying said semiconductor substrate;
• depositing a silicon nitride layer overlying said pad oxide layer wherein said silicon nitride layer is deposited to a thickness of between about 600 Angstroms and 1,300 Angstroms;
• depositing a protective layer overlying said silicon nitride layer wherein said protective layer comprises SiOxNy (stoichiometric silicon oxynitride);
• patterning said protective layer, said silicon nitride layer, and said pad oxide layer to expose said semiconductor substrate where shallow trench isolations are planned;
• etching said semiconductor substrate to form trenches for said planned shallow trench isolations wherein the presence of said protective layer prevents etching of said silicon nitride layer during said etching;
• depositing a trench filling layer overlying said protective layer and filling said trenches;
• and
• polishing down said trench filling layer and said protective layer to complete said shallow trench isolations in the manufacture of the integrated circuit device.