New EPROM Data-Loss Mechanisms

Data-loss mechanisms in present-generation EPROMs have been studied. Defect-related data loss is primarily due to interpoly-oxide defects. This is a change from the previous generation and introduces a new EPROM failure mode--column data loss. Contamination-compensation is found to be due as much to field-driven motion as to diffusion, and one result is that contaminated regions can exhibit charge gain as well as charge loss. Intrinsic charge loss is attributed to detrapping of electrons from the oxide layers rather than to loss of stored charge, suggesting that with proper screening of defects EPROM data retention is effectively unlimited.