Multi-level cell memory device and operating method thereof

A method of operating a non-volatile memory device, comprising:

• performing a first hard decision read operation that includes applying a first read voltage to a selected word line of the non-volatile memory device;
• storing a result of the first hard decision read operation at a first latch of a page buffer in the non-volatile memory device;
• performing a second hard decision read operation that includes generating hard decision data by applying a second read voltage to the selected word line, the second read voltage being higher than the first read voltage;
• generating a first soft decision value using a result of the first hard decision read operation stored at the first latch without applying a first soft decision read voltage to the selected word line;
• storing the first soft decision value at a second latch of the page buffer;
• generating a second soft decision value by applying a soft decision read voltage to the selected word line, the soft decision read voltage being higher than the second read voltage;
• storing the second soft decision value at a third latch of the page buffer;
• and
• generating soft decision data using the page buffer by performing a logical operation on the first soft decision value and the second soft decision value.

An method of operating a non-volatile memory device including at least one cell string having memory cells arranged between a string select transistor and a ground select transistor in a direction perpendicular to a substrate, the method of operating comprising:

• performing a first hard decision read operation that includes applying a first voltage to a selected word line of the non-volatile memory device;
• storing a result of the first hard decision read operation at a first latch of a page buffer of the non-volatile memory device;
• performing a second hard decision read operation that includes applying a second voltage to the selected word line,
• the second voltage being higher than the first voltage;
• and
• generating a first soft decision value using a result of the first hard decision read operation stored at the first latch without applying a first soft decision read voltage to the selected word line.

A method of operating a non-volatile memory device, comprising:

• performing a first read operation that includes applying a first voltage to a selected word line of the non-volatile memory device;
• storing a result of the first read operation at a first latch of a page buffer of the non-volatile memory device;
• performing a second read operation that includes applying a second voltage to the selected word line, the second voltage being higher than the first voltage;
• performing an error correction operation on a result of the second read operation;
• and
• performing an additional error correction operation using soft decision data if the error correction operation on the result of the second read operation fails,
• generating the soft decision data by,
• performing a third read operation that includes applying a third voltage to the selected word line, the third voltage being higher than the second voltage,
• storing a result of the third read operation in an other latch of the page buffer, and
• performing a logical operation using the result of the first read operation stored in the first latch and the result of the third read operation stored in the other latch.