Statistical Evaluation of Process Damage Using an Arrayed Test Pattern in a Large Number of MOSFETs

Evaluating the statistical variations of MOSFETs is important for realizing accurate analog circuits and large-scale-integration devices. A new evaluation method for the statistical variation of the electrical characteristics of MOSFETs is presented. We have developed a test circuit for understanding the statistical and local variations of MOSFETs in a very short time. We demonstrate that the electrical characteristics in more than one million MOSFETs, such as the threshold voltage and the subthreshold swing (S-Factor), are measured in 30 min and that the measured results are very efficient in developing the fabrication process, the process equipment, and the device structure to reduce the statistical and local characteristic variation.