The increase in the electrical characteristic variability of MOSFETs caused by the miniaturization of MOSFETs is one of the critical issues for realizing the low power consumption of large-scale-integrated circuits and the high accuracy of analog devices. It is necessary to easily evaluate the variability of a very large number of MOSFETs in a very short time for short-period- developing fabrication processes and device structures. We have proposed and developed a simple test structure for evaluating the electrical characteristics of over 1.2 million MOSFETs such as threshold voltage (V th), subthreshold swing (S-factor) in around 30 min. The accuracy of the test circuit developed is 1.9 mV, as 3σ. We have also evaluated the V th distribution, the S-factor distribution, and the dependence of V th variability on the gate size and antenna ratio of MOSFETs. The measurement results are very useful in developing fabrication processes, process equipment, and device structures, that suppress the variability.
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