Gate-oxide breakdown accelerated by large drain current in n-channel MOSFET´s

A study of the time-dependent dielectric breakdown (TDDB) of thin gate oxides in small n-channel MOSFETs operated beyond punchthrough is discussed. Catastrophic gate-oxide breakdown is accelerated when holes generated by the large drain current are injected into the gate oxide. More specifically, the gate-oxide breakdown in a MOSFET (gate length=1.0 mu m, gate width-15 mu m) occurs in approximately 100 s at an applied gate oxide field of approximately 5.2 MV/cm during the high drain current stress, while it occurs in approximately 100 s at an applied gate oxide field of approximately 10.7 MV/cm during a conventional time-dependent dielectric breakdown (TDDB) test. The results indicate that the gate oxide lifetime is much shorter in MOSFETs when there is hot-hole injection than that expected using the conventional TDDB method.<>