HOLE ACCUMULATION IN SIO2/SI3N4/SIO2 CAPACITORS PRIOR TO DIELECTRIC-BREAKDOWN

Supporting evidence for the time-dependent dielectric breakdown (TDDB) of an SiO2/Si3N4/SiO2 (ONO) capacitor due to hole accumulation has been obtained: 1) the gate current of the ONO capacitor during constant voltage stress continues to increase prior to dielectric breakdown, 2) after stress with a positive gate bias, the midgap voltage shifts toward the negative voltage direction, and 3) the time-to-breakdown is inversely proportional to the gate current. These suggest that holes injected from the anode accumulate in the vicinity of the Si3N4/SiO2 interface near the cathode, which cause the breakdown of ONO capacitors.