Non-volatile memory device for improving data reliability and operating method thereof

An operating method of a memory device including a memory cell array which includes a plurality of word lines and includes a normal area including some of the plurality of word lines and a deterioration area including other word lines of the plurality of word lines, the operating method comprising:

• programming data of at least one first bit in each of memory cells connected to word lines of a first group of the deterioration area;
• after the programming on the word lines of the first group is completed, programming data of at least two second bits in each of memory cells connected to word lines of a second group of the deterioration area, wherein the at least two second bits are more than the at least one first bit;
• and
• performing programming on the word lines of the normal area,
• wherein a threshold voltage level corresponding to an erase state of each of the word lines of the first group is higher than a threshold voltage level corresponding to an erase state of each of the word lines of the second group.

An operating method of a memory device including a memory cell array which includes a deterioration area including word lines of a first group and word lines of a second group, the operating method comprising:

• programming data of at least one first bit in each of memory cells connected to the word lines of the first group;
• after the programming on the word lines of the first group is completed, programming data of at least two second bits in each of memory cells connected to the word lines of the second group, wherein the at least two second bits are more than the at least one first bit;
• performing an erase operation using a first verify voltage on the word lines of the first group;
• and
• performing an erase operation using a second verify voltage on the word lines of the second group,
• wherein a level of the first verify voltage is higher than a level of the second verify voltage, and a threshold voltage level after an erase operation on the word lines of the first group is higher than a threshold voltage level after an erase operation on the word lines of the second group.