Locos technology with reduced junction leakage

摘要

A field oxide structure having a reduced number of defects is described. A field oxide mask is formed over a substrate having openings which expose portions of the substrate where the field oxide structures are to be formed. Silicon nitride spacers are formed on the sidewalls of the openings. Channel stop ions are selectively implanted through the opening into the substrate and then the thick field oxide structures are formed. Stress-generated crystalline defects are formed underlying the field oxidation regions at the edges of the openings. The silicon nitride spacers are removed. An additional source/drain ion implantation is performed by implanting ions to doped regions in the substrate deep enough into the substrate so that the crystalline defects are enclosed within the implanted regions to reduce junction leakage. The silicon dioxide, silicon nitride, and pad silicon oxide layers are removed to complete the field oxide structure.