Methods of program-verifying a multi-bit nonvolatile memory device and circuit thereof

Abstract

Methods of verifying a program state may be provided for a non-volatile memory device including a multi-bit memory cell transistor providing more than two different program states. More particularly, the multi-bit memory cell transistor may be programmed from a first program state to a second program state, and a reference memory cell corresponding to the second program state may be selected. After programming the multi-bit memory cell transistor to the second program state and after selecting the reference memory cell corresponding to the second program state, a current flowing through the multi-bit memory cell transistor programmed to the second memory state and a current flowing through the reference memory cell may be compared. Programming the multi-bit memory cell transistor to the second program state may then be verified responsive to comparing the currents flowing through the multi-bit memory cell and the reference memory cell.