Degradation in metal-oxide-semiconductor structure with ultrathin gate oxide due to external compressive stress

The effect of external stress on metal-oxide-semiconductor (MOS) structure with ultrathin gate oxide (similar to1.5 nm) was studied. J-V characteristi cs of fresh and stressed samples revealed that the tensile stress had littl e effect on J-V curves, whereas the compressive stress obviously increased the leakage current by about several hundred in percentages with respect to the fresh sample, in both positive and negative gate biases. This increase in leakage current was suggested to be attributed to the increase of inter face states and silicon bulk traps under external compressive stress in the MOS device with an inherent tensile stressed silicon. In addition, we also found that once the device was damaged by the previously applied compressi ve stress, the second applied compressive stress of the same magnitude woul d not create more damage unless the device was breakdown. (C) 2001 American Institute of Physics.