Evaluation of Electron Shading Charge Buildup Damage Using Metal-Nitride-Oxide-Silicon Capacitors

The damage from plasma-induced charge buildup caused by the "electron shading" effect was investigated in a pulse-modulated plasma using metal-nitride-oxide-silicon (MNOS) capacitors. The reduction of charge buildup depends strongly on the on-time. When the on-time is shorter than 50 µ s and the off-time is constant at 100 µ s, the potential difference between high and low aspect ratio patterns, ΔV, becomes zero. However, the shift in the flatband voltage is large in the case of 33.3 µ s on-time, and it corresponds to the degradation of the gate oxide. The potential of the silicon substrate is thought to become low compared to the polysilicon electrode. This indicates that the potential of the silicon substrate must also be controlled.