Mercury-probe characterisation of soft breakdown: effect of oxide thickness and measurement set-up

The breakdown of 4-7 nm gate oxides is investigated using fast-feedback Hg-probe measurements to perform Exponentially Ramped Current Stress (ERCS) tests. Soft breakdown is detected in oxides thinner than 5 nm. However, it is found that the detection of soft-breakdown during ERCS test depends on the measurement set-up. In particular, it can be completely suppressed by reducing the gate oxide capacitor area. The consequences of this result for correct routine assessment of gate oxide integrity in microelectronic manufacturing are discussed. © 1999 Elsevier Science Ltd. All rights reserved.