Analytical Percolation Model for Predicting Anomalous Charge Loss in Flash Memories

Abstract

Data retention in flash memories is limited by anomalous charge loss. In this work, this phenomenon is modeled with a percolation concept. An analytical model is constructed that relates the charge-loss distribution of moving bits in flash memories with the geometric distribution of oxide traps. The oxide is characterized by a single parameter, the trap density. Combined with a trap-to-trap direct tunneling model, the physical parameters of the electron traps involved in the leakage mechanism are determined. Flash memory failure rate predictions for different oxide qualities, thicknesses and tunnel-oxide voltages are calculated.