Method for programming a reference cell

摘要

The nitride ROM (NROM) reference cell is fast-pulse programmed by raising a drain voltage in large steps until above a threshold interim voltage. It is then slow programmed with a fixed drain voltage in small steps until above a final target level, where the interim target level is 100-400mV below the final level but greater than an expected threshold voltage raise from the pulse. The threshold voltage level is measured after each programming pulse.