CMOS Gate Oxide Integrity Failure Structure Analysis Using Transmission Electron Microscopy

In this paper, cross-sectional TEM combined with plan-view TEM analysis was employed to investigate the gate oxide integrity (GOI) failure isolated using infrared optical beam induced resistance change (IR-OBIRCH) method. The cross-sectional TEM investigation only shows gate oxide breakdown and fused active under the spacer. However, plan-view TEM analysis reveals clearly the breakdown happened at the poly edge due to smaller spacer related to over etch of spacer nitride or oxide. EF-TEM elemental mapping shows Co migrates electrically to the fused active area