Hot-Electron-Induced Instability in 0.5-μm p-Channel MOSFET’s Patterned Using Synchrotron X-ray Lithography

Abstract

Radiation enhanced hot-electron induced instability in p- channel MOSFET’s patterned using X-ray lithography is reported in this paper. 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 MOSFET’s is significantly increased due to the enhanced electron trapping in the oxide by residual traps. However, the degradation in n-channel MOSFET’s due to channel hot carriers is not significantly increased by X-ray lithography since n-channel MOSFET’s are susceptible to interface state generation by hot carriers but are relatively insensitive to the degradation due to the electron trapping. These results suggest that p-channel MOSFET’s in addition to n-channel MOSFET’s need to be carefully examined in terms of hotcarrier-induced instability in CMOS VLSI circuits patterned using X-ray lithography and/or when the radiation damage is incurred in the backend-of-the-line processing.© 1989 IEEE