Effect of Electron Shading on Gate Oxide Degradation

The oxide degradation due to edge and electron shading effects is investigated in a pulse-modulated plasma using metal-oxide-silicon (MOS) and metal-nitride-oxide-silicon (MNOS) capacitors. Reduction of edge defect, shading defect and electron shading charge build-up is strongly dependent on the on-time in pulse plasma. In particular, when the on-time is shorter than 50 µs, the coefficient of the shading defect becomes almost zero. The investigation of MNOS capacitors, which have the patterns with or without the substrate contact antenna, indicates that the electric stress direction applied to gate oxide changes as the device structure changes.