Reverse vt-state operation and optimized bics device structure

Abstract

Systems and methods for improving the reliability of non-volatile memory by reducing the number of memory cell transistors that experience excessive hole injection are described. The excessive hole injection may occur when the threshold voltage for a memory cell transistor is being set below a particular negative threshold voltage. To reduce the number of memory cell transistors with threshold voltages less than the particular negative threshold voltage, the programmed data states of the memory cell transistors may be reversed such that the erased state comprises the highest data state corresponding with the highest threshold voltage distribution. To facilitate programming of the memory cell transistors with reversed programmed data states, a non-volatile memory device structure may be used in which the bit line connections to NAND strings comprise direct poly-channel contact to P+ silicon and the source line connections to the NAND strings comprise direct poly-channel contact to N+ silicon.