Oxide liner for high reliability with reduced encroachment of the source/drain region

摘要

A semiconductor process in which a first nitrogen bearing oxide is formed on an upper surface of a semiconductor substrate. A silicon nitride layer is then formed on the nitrogen bearing oxide. The first oxide and the silicon nitride layer are then patterned to expose an upper surface of the substrate over a trench region of the substrate. An isolation trench is then etched into the trench region of the substrate and a nitrogen bearing liner oxide is then formed on sidewalls and a floor of the trench. An isolation dielectric is then formed within the trench and, thereafter, the silicon nitride layer is removed from the wafer. A suitable thickness of the first nitrogen bearing oxide and of the liner oxide is in the range of approximately 30 to 100 angstroms. A consumption of adjacent active regions caused by the thermal oxidation process is preferably less than approximately 50 angstroms.