Program refresh for non-volatile memory cells

A semiconductor device, comprising:

• a plurality of memory cells formed on a semiconductor substrate;
• and control circuitry to:
• program a first memory cell of the plurality of memory cells to a first program state that is associated with a first program verify voltage and a first reference voltage such that the first memory cell has a first threshold voltage that meets or exceeds the first program verify voltage, wherein the first program verify voltage is greater than the first reference voltage;
• determine in a first read operation that the first threshold voltage of the first memory cell has drifted down to between the first program verify voltage and the first reference voltage;
• and
• in response to the determination in the first read operation, program the first memory cell to increase the first threshold voltage of the first memory cell to meet or exceed the first program verify voltage.