Heavy-Ion-Induced Breakdown in Ultra-Thin Gate Oxides and High-k Dielectrics

We present experimental results on single-event-induced breakdown in sub-5-nm plasma-enhanced SiO2, nitrided SiO2, Al2O3, HfO2, and Zr0 4Si1 6O4 dielectrics typical of current and future-generation commercial gate oxides. These advanced oxides are found to be quite resistant to ion-induced breakdown. Radiation-induced soft breakdown was observed in some films with 342 MeV Au (LET = 80 MeV/mg/cm) but not 340 MeV I (LET = 60 MeV/mg/cm). The critical voltage to hard breakdown was found to scale with the square root of the physical oxide thickness, not with the energy stored on the gate capacitance. Alternative dielectrics with equivalent oxide thickness substantially below their physical thickness were found to exhibit significantly higher voltage to hard breakdown than SiO2 counterparts. All of the samples reached ion-induced hard breakdown at applied voltages well above typical operating power-supply voltages; these findings bode well for the use of advanced commercial integrated circuits in space systems.