| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a nonvolatile memory unit including an indicator cell, and to provide a multilevel cell programming method which can skip part of the verification process utilizing the indicator cell. <P>SOLUTION: The multilevel cell programming method includes steps of: applying different data to each cell so that mutually different threshold voltages are set to the plurality of the main cells and indicator cells; carrying out programming operations to the main cell and the indicator cells; carrying out the first verification operation to the main cell and the indicator cells by setting the first verification voltage as a reference; sequentially repeating the programming operations and the first verification operation until the threshold voltage of the first cell exceeds the first verification voltage; carrying out the second verification operation to the main cell with the second verification voltage as the reference, when the threshold voltage of the first cell exceeds the first verification voltage. <P>COPYRIGHT: (C)2009,JPO&INPIT</p> |
