| 摘要 |
A nonvolatile memory device comprises a plurality of first memory cells. Each of the first memory cells stores a plurality of data bits as one of a plurality of threshold voltages corresponding to a plurality of logic states. The method for setting a default read voltage of the nonvolatile memory device comprises the following steps of: programming first data in the first memory cells to uniformly use logic states of the first memory cells; applying a first default read voltage, which is included in default read voltages, to word lines, which are connected to the first memory cells, and measuring a first ratio of first on-cells having a threshold voltage lower than the first default read voltage among the first memory cells; and changing the first default read voltage based on the first ratio and a first reference value corresponding to the first default read voltage. |
