Effects of pre-stress on hot-carrier degradation of N-channel MOSFETs

N-channel Metal Oxide Field-Effect Transistors (nMOSFETs) degrade following a power-law in time: tⁿ where n<;1 typically. This ideal degradation curve can be distorted in devices that have been subject to certain types of pre-stress. Such distortion can cause erroneous lifetime extrapolations, unless accounted for in analysis. This paper describes various types of pre-stress and their effect on hot-carrier degradation of L=0.5 μm nMOSFETs designed for 5 V operation. We show how taking into account pre-stress is critical for proper analysis and interpretation of degradation behavior used to guide robust device design.