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Long-term reliability results over six orders of magnitude in time are presented showing that the voltage acceleration model for ZrO2/SiO2/ZrO2 exhibits an exponential dependence with voltage, down to 2 V. The voltage acceleration parameter gamma is between 10 and 15 V-1, depending on the biasing polarity. Soft-breakdown behavior (SILC) is evident prior to the onset of hard breakdown as a result of barrier lowering or charge accumulation in the high- k film. Under ac stress conditions, this SILC branch is lowered in magnitude, translating to a gain in lifetime to breakdown.

A second current-acceleration method for measuring the reliability of silicon bipolar transistors under reverse emitter-base bias stress is demonstrated in this paper. The low-voltage operation condition in submicron transistors may be attained during the stress experiments, providing an accurate determination of the transistor's operation time-to-failure (TTF) without extrapolating from higher voltage stress data. Two different current-acceleration stress methods are demonstrated in one transistor design and compared with the traditional voltage-acceleration method using the carrier kinetic energy as the independent variable. It is shown that the traditional voltage-acceleration method can give an erroneous and larger extrapolated time-to-failure by several orders of magnitude in some devices.

It is argued that base current reversal in an advanced n-p-n bipolar transistor arises from the same physical mechanism as classical bipolar snapback. Measurements of the bipolar snapback voltage, BV/sub CE0/, and of the collector-emitter voltage required for base current reversal, V/sub CE/Br/ are identical over a range of variation in transistor design and over more than eight orders of magnitude in collector current. The minimum or sustaining values of BV/sub CE0/, or V/sub CE/Br/, should be used for the purposes of bipolar device design rather than the larger trigger value measured at very low current levels. The former is an indication of electric field strength in the collector-base depletion region while the latter is a monitor of the level of the nonideal base current component. Measurement of base current reversal provides a more consistent and less destructive technique of characterizing bipolar sustaining voltage. >