Soft-breakdown damage in MOSFET´s due to high-density plasma etching exposure

Gate leakage current densities on the order of nA/μm² at operating voltage levels have been observed in MOSFET´s that were processed in a high-density plasma (HDP) oxide etch tool, yet these transistors have performance parameters that are within 10% of controls. These high gate leakage currents seen in the HDP etched devices were not observed in controls. Direct observation shows that these HDP exposed devices have light emission at higher voltages in the region where the gate poly-Si crosses the birds beak. Light emission in this region is also not observed in controls.