High Endurance Sonos Technology Improved by Design & Process Optimization

In this paper, we present a design and process optimization to improve SONOS cell endurance cycle. Generally, the endurance cycle can be effectively increased by reducing the voltage. But with the voltage dropping, large VT margin loss will be found. In this case, we design a differential cell which can enlarge cell VT window. In addition, we optimize the process condition to get the ideal VT window of the differential cell. Finally, the endurance cycle of SONOS IP(512Kb) is improved from 500K to 25M cycles at 85 degrees.