Hot-electron-induced instability in 0.5- mu m p-channel MOSFETs patterned using synchrotron X-ray lithography

Radiation damage caused by X-ray includes positive oxide charge, neutral traps, and interface states. Although several annealing steps are performed throughout the entire fabrication process, the radiation damage, particularly neutral traps, is not completely annealed out. The hot-electron-induced instability in p-channel MOSFETs is significantly increased due to the enhanced electron trapping in the oxide by residual traps. However, the degradation in n-channel MOSFETs due to channel-hot carriers is not significantly increased by X-ray lithography since n-channel MOSFETs are susceptible to interface state generation by hot carriers but are relatively insensitive to the degradation due to electron trapping. The results suggest that p-channel MOSFETs in addition to n-channel MOSFETs need to be carefully examined for hot carrier-induced instability in CMOS VLSI circuits patterned using X-ray lithography and/or when the radiation damage is incurred in the back-end-of-the-line processing.<
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