Method of operating a dual cell memory device having an improved read margin over lifetime

A method for programming a charge trapping dielectric memory device (6) having a first charge storing cell (38, 40) and a second charge storing cell (38, 40), the method comprising: strong quenching of the first and the second charge storing cell to shift a threshold voltage of the erased state of the memory device to a lower value than a threshold voltage in the natural state; Programming the first charge storing cell to store a first amount of charge corresponding to a first programming state selected from a blank program level and a first charged program level; and Programming the second charge storing cell to store a second amount of charge corresponding to a second programming state selected from the blank program level and a second charged program level.