Method to monitor the kink effect

摘要

This invention relates to the characterization of integrated circuit devices and more particularly to an improved method for monitoring for unacceptable kink behavior, in the threshold voltage characteristics of FET devices, that can be caused by a tendency for reduced gate oxide thickness and reduced substrate doping concentration, along the length of channel regions bounded by STI. This is achieved by comparing a pair of drain current versus gate voltage characteristics, as a function of two values of substrate voltage. Relative voltage shifts between the two curves are compared at a value of drain current that is well below the kink and at a value of drain current that is well above the kink. The quantitative degree of kink behavior is determined by how much greater the voltage shift, corresponding to the value of drain current well above the kink, exceeds the voltage shift, corresponding to the value of drain current well below the kink.