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Semiconductor memory device

  • US 9,818,487 B2
  • Filed: 02/27/2017
  • Issued: 11/14/2017
  • Est. Priority Date: 09/06/2012
  • Status: Active Grant
First Claim
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1. A semiconductor memory device, comprising:

  • a memory block including a plurality of memory strings, the plurality of memory strings including a first memory string and a second memory string, the first memory string including a first transistor, a second transistor and a plurality of first memory cells, the second memory string including a third transistor, a fourth transistor and a plurality of second memory cells;

    a first bit line connected to a node of the first transistor and a node of the third transistor;

    a first select gate line connected to a gate of the first transistor;

    a second select gate line connected to a gate of the third transistor;

    a source line connected to a node of the second transistor and a node of the fourth transistor;

    a plurality of word lines, each of the word lines connected to one of gates of the first memory cells and one of gates of the second memory cells;

    a controller configured to control an erase verify operation of the memory block, wherein the erase verify operation includes;

    applying a first selection voltage to the first select gate line at a first time;

    while applying the first selection voltage to the first select gate line, applying an erase verify voltage to the plurality of word lines; and

    applying a second selection voltage to the second select gate line at a second time after the first time without making the voltage applied to the plurality of word lines zero voltage at any time between the first time and the second time.

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