SOFT-BREAKDOWN DAMAGE IN MOSFETS DUE TO HIGH-DENSITY PLASMA-ETCHING EXPOSURE

Gate leakage current densities on the order of nA/mu m(2) 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 hav e performance parameters that are within 10% of controls. These high a te leakage currents seen in the HDP etched devices were not observed i n controls. Direct observation shows that these HDP exposed devices ha ve 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.