Leakage Current in Sub-Quarter Micron MOSFET: A Perspective on Stressed Delta I DDQ Testing

The effectiveness of single threshold I _DDQ measurement for defect detection is eroded owing to higher and more variable background leakage current in modern VLSIs. Delta I _DDQ is identified as one alternative for deep submicron current measurements. Often delta I _DDQ is coupled with voltage and thermal stress in order to accelerate the failure mechanisms. A major concern is the I _DDQ limit setting under normal and stressed conditions. In this article, we investigate the impact of voltage and thermal stress on the background leakage. We calculate I _DDQ limits for normal and stressed operating conditions of 0.18 m n-MOSFETs using a device simulator. Intrinsic leakage current components of transistor are analyzed and the impact of technology scaling on effectiveness of stressed I _DDQ testing is also investigated.