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Method of reducing hot electron injection type of read disturb in dummy memory cells

  • US 9,406,391 B1
  • Filed: 10/27/2015
  • Issued: 08/02/2016
  • Est. Priority Date: 01/26/2015
  • Status: Active Grant
First Claim
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1. A method for performing a sensing operation in a memory device, the method comprising:

  • while a bit line of an unselected NAND string is at a driven voltage, requesting a voltage driver of a select gate line to provide a step up of a voltage on the select gate line, requesting a voltage driver of a first dummy word line to provide a first step up of a voltage on the first dummy word line, and requesting a voltage driver of unselected word lines to provide a first step up of a voltage on the unselected word lines, wherein the bit line is connected to a selected NAND string, the select gate line is connected to a drain-side select gate transistor at a drain-side of the unselected NAND string and a drain-side select gate transistor at a drain-side of the selected NAND string, the first dummy word line is connected to a first dummy memory cell in the unselected NAND string adjacent to the drain-side select gate transistor of the unselected NAND string and to a first dummy memory cell in the selected NAND string adjacent to the drain-side select gate transistor of the selected NAND string, a selected word line is connected to a selected memory cell in the selected NAND string and to a corresponding unselected memory cell in the unselected NAND string, the unselected word lines are connected to unselected memory cells in the selected NAND string and to corresponding unselected memory cells in the unselected NAND stringsubsequently, requesting the voltage driver of the select gate line to provide a step down of the voltage on the select gate line to a stepped down level; and

    while the voltage on the select gate line is at the stepped down level;

    requesting the voltage driver of the unselected word lines to provide a second step up of the voltage of the unselected word lines,requesting the voltage driver of the first dummy word line to provide a second step up of the voltage of the first dummy word line,requesting a voltage driver of the selected word line to provide one or more voltages on the selected word line, andsensing the selected memory cell while the selected word line is at the one or more voltages.

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