A memory cell with a charge trapping structure has multiple bias
arrangements. Multiple cycles of applying the bias arrangements lowering
and raising a threshold voltage of the memory cell leave a distribution
of charge in the charge trapping layer. The charge interferes with the
threshold voltage achievable in the memory cell. This distribution of
charge is balanced by applying a charge balancing bias arrangement at
intervals during which a plurality of program and erase cycles occurs.
Also, the charge balancing bias arrangement is applied prior to the
beginning of program and erase cycles of the memory cell.