Basic feasibility constraints for multilevel CHE-programmed flash memories

This paper discusses the basic constraints for the feasibility of multilevel (NM) Flash memories, with specific reference to devices programmed by channel hot electron injection. Issues such as programming algorithm, program and read disturb immunity, data retention, and sense circuitry sensitivity are considered. Experimental data concerning the most suited programming algorithm and reliability aspects are given. A guideline for the evaluation of NIL storage feasibility is provided, and a simple set of equations for basic constraint estimation is derived.