Bias-Temperature-Stess Studies of Change Retention in Dual-Dielectric, Charge-Storage Cells

Bias-Temperature-Stress Studies of Charge Retention in Dual-Dielectric, Charge-Storage Cells By K. K. THORNBER, D. KAHNG, and C. T. NEPPELL ( M a n u s c r i p t r e c e i v e d February 19, 1974) We ·present a simple, relatively efficient method to predict the nonvolatility of dual-dielectric, charge-storage cells. Using this method, charge-retention times of several hundred years can be predicted unambiguously from experiments of several days' duration made at elevated temperatures and vrith externally applied, accelerating fields. The method is first presented in the context of a simple, physically reasonable model of the bias and temperature dependence of the characteristic relaxation time of the device. It is then used to analyze a particular device structure. At 80°C, we predict that this device can maintain a flatband-voltage shift in excess of 4 volts for approximately 500 years. Our analysis suggests that this method can be applied to a variety of dual-dielectric, charge-storage cells to predict their nonvolatilities.