NOVEL PUNCH-THROUGH FREE PROGRAM SCHEME FOR NT-STRING FLASH DESIGN

摘要

A nonvolatile memory array has nonvolatile memory cells arranged in rows and columns where each column has a bit line and source line associated with and in parallel with the nonvolatile memory cells. In programming the nonvolatile memory cell, approximately equal program voltage levels are applied to a drain and a source of a selected charge retaining transistor such that the difference in the voltage between the drain and the source of the selected charge retaining transistor is less than a drain to source breakdown voltage of the selected charge retaining transistor to prevent drain-to-source punch through. In programming or erasing the nonvolatile memory cell a control gate and a bulk program voltage level is applied to a control gate and bulk such that the magnitude of the control gate and bulk program voltage levels is less than a breakdown voltage level of peripheral circuitry.