Erase and program operations for memory devices having multiple storage modes

A memory device, comprising:

• a memory array;
• and
• a peripheral circuit coupled to the memory array and configured to perform operations comprising:
• selecting a portion of a memory array, wherein the portion of the memory array is programmable in a first storage mode or a second storage mode, wherein:
• the second storage mode has a lower storage density than the first storage mode, and
• the first storage mode corresponds to a first erase operation using a first effective erase voltage;
• and
• performing a switch erase operation to switch the portion of the memory array from the first storage mode to a switched second storage mode, wherein the switched second storage mode has a same storage density as the second storage mode and corresponds to the switch erase operation, and wherein after performing the switch erase operation, a threshold voltage of a memory cell of the portion of the memory array is higher than a threshold voltage of the memory cell of the portion of the memory array after performing the first erase operation.

A method for operating a memory device, comprising:

• selecting a portion of a memory array, wherein the portion of the memory array is programmable in a first storage mode or a second storage mode, wherein:
• the second storage mode has a lower storage density than the first storage mode, and
• the second storage mode corresponds to a second program operation;
• and
• performing a switch program operation to switch the portion of the memory array in the first storage mode to a switched second storage mode, wherein the switched second storage mode has a same storage density as the second storage mode and corresponds to the switch program operation, and wherein the switch program operation is different from the second program operation of the second storage mode.