Semi-circle drain side select gate maintenance by selective semi-circle dummy word line program

A controller in communication with a memory apparatus including memory cells connected to one of a plurality of word lines including at least one dummy word line and a plurality of data word lines and arranged in one or more strings and configured to retain a threshold voltage corresponding to one of a plurality of memory states, the controller configured to:

• instruct the memory apparatus to identify ones of the memory cells connected to the at least one dummy word line having the threshold voltage being below a predetermined detection voltage threshold following an erase operation;
• and
• reduce threshold voltage down shifting of a semi-circle drain side select gate by instructing the memory apparatus to selectively apply at least one programming pulse of a maintenance program voltage to the at least one dummy word line to program the ones of the memory cells connected to the at least one dummy word line having the threshold voltage being below the predetermined detection voltage threshold.

A method of operating a memory apparatus including memory cells connected to one of a plurality of word lines including at least one dummy word line and a plurality of data word lines and arranged in one or more strings and configured to retain a threshold voltage corresponding to one of a plurality of memory states, the method comprising the steps of:

• identifying ones of the memory cells connected to the at least one dummy word line having the threshold voltage being below a predetermined detection voltage threshold following an erase operation;
• and
• reduce threshold voltage down shifting of a semi-circle drain side select gate by selectively applying at least one programming pulse of a maintenance program voltage to the at least one dummy word line to program the ones of the memory cells connected to the at least one dummy word line having the threshold voltage being below the predetermined detection voltage threshold.