A new twin-well CMOS process using nitridized-oxide-LOCOS (NOLOCOS) isolation technology

A twin-well CMOS process using the nitridized pad-oxide film as a buffer for the enhanced local oxidation of silicon (LOCOS) in which the nitridized pad oxide is used to obtain a defect-free and near-zero bird's beak field isolation structure is discussed. The principal feature of the process is that high-temperature nitridation of the thin pad oxide is simultaneously used to increase the junction depth of the As-implanted n-well. Both n- and p-channel MOSFETs fabricated by the twin-cell CMOS process using the nitridized-oxide-LOCOS (NOLOCOS) isolation technology are characterized and compared to those fabricated by the conventional LOCOS isolation technique. The major features of the NOLOCOS isolation technology in CMOS/VLSI fabrication are clearly demonstrated.<
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