| 摘要 |
<p>Programming algorithms suitable for non-volatile memory devices are presented, where the usual staircase type of waveform is decomposed into multiple passes. The same pulses are used, but their order is different, being broken down into N subsets of every N-th pulse so that there are N programming passes. For example, in a four pass version the first pass would sequentially have pulses (1, 5, 9, ) of the staircase; the second pass would have pulses (2, 6, 10, ); and so on for the third and fourth passes. By using a large step size for stepping up the program voltage VPGM, pre-verify and shifted verify margins for the different passes, a narrow distribution can be obtained with multiple passes. Also, in a complementary set of features, a quick pass write (QPW) can be done without the drawback of doing QPW verify by the use of shared verify levels.</p> |
