Non-volatile memory device, operation method thereof, and devices having the non-volatile memory device

A program method for a non-volatile memory device comprising:

• programming a first multi-level cell among multi-level cells of the non-volatile memory device to a first state of a first group of states according to a first verify voltage level of a first group of verify voltage levels;
• and
• re-programming the first multi-level cell to a first state of a second group of states according to a first verify voltage level of a second group of verify voltage levels, each verify voltage level of the second group of verify voltage levels having a higher verify voltage level than any verify voltage levels of the first group of verify voltage levels,
• wherein one of the states of the second group of states includes at least one of the states of the first group of states.

A read method for a non-volatile memory device comprising:

• providing a first read voltage to a selected word line to read a particular bit of a multi-bit memory cell;
• determining whether the memory cell is in a re-programmed state based on the first provided read voltage;
• providing a second read voltage to the selected word line to read the particular bit of the memory cell, when it is determined that the memory cell is not in a re-programmed state;
• and
• reading the particular bit according to the second read voltage,
• wherein a level of the second read voltage is smaller than a level of the first read voltage.