Enable open sub-block erase in sub-block mode operation

A controller in communication with a memory apparatus including memory cells each connected to one of a plurality of word lines and configured to retain a threshold voltage corresponding to one of a plurality of data states, the memory cells form a block including an unselected sub-block for an erase operation and a selected sub-block for the erase operation, the controller configured to:

• identify ones of the plurality of word lines of the unselected sub-block that are programmed, and
• instruct the memory apparatus to apply a selected erase enable voltage to ones of the plurality of word lines of the selected sub-block while applying an unselected erase enable voltage to ones of the plurality of word lines of the unselected sub-block to erase the memory cells of the selected sub-block during the erase operation, the unselected erase enable voltage being different for ones of the plurality of word lines of the unselected sub-block that are programmed than for ones of the plurality of word lines of the unselected sub-block that are erased.

A method of operating a memory apparatus including memory cells each connected to one of a plurality of word lines and configured to retain a threshold voltage corresponding to one of a plurality of data states, the memory cells form a block including an unselected sub-block for an erase operation and a selected sub-block for the erase operation, the method comprising the steps of:

• identifying ones of the plurality of word lines of the unselected sub-block that are programmed;
• and
• applying a selected erase enable voltage to ones of the plurality of word lines of the selected sub-block while applying an unselected erase enable voltage to ones of the plurality of word lines of the unselected sub-block to erase the memory cells of the selected sub-block during the erase operation, the unselected erase enable voltage being different for ones of the plurality of word lines of the unselected sub-block that are programmed than for ones of the plurality of word lines of the unselected sub-block that are erased.