Adjusting voltage on adjacent word line during verify of memory cells on selected word line in multi-pass programming
First Claim
1. An apparatus, comprising:
- a set of memory cells arranged in NAND strings and connected to a plurality of word lines, the plurality of word lines comprising a selected word line and unselected word lines; and
a control circuit, the control circuit to perform verify tests for memory cells connected to the selected word line in one program loop, is configured to apply a plurality of verify voltages in turn to the selected word line, and during the application of each verify voltage, sense a conductive level of the memory cells connected to the selected word line and apply a variable voltage to a first adjacent word line of the selected word line, wherein the variable voltage is a first increasing function of the verify voltages.
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Abstract
Apparatuses and techniques are described for programming memory cells with a narrow threshold voltage (Vth) distribution in a memory device. In one approach, the final pass of a multi-pass program operation on a word line WLn includes applying a variable voltage to WLn+1 during verify tests on WLn. The variable voltage (Vread) can be an increasing function of the verify voltage on WLn, and thus a function of the data state for which the verify test is performed. In one approach, Vread on WLn+1 is stepped up with each increase in the verify voltage on WLn. The step size in Vread can be the same as, or different than, the step size in the verify voltage. Vread can be different for each different verify voltage, or multiple verify voltages can be grouped for use with a common Vread.
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Citations
20 Claims
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1. An apparatus, comprising:
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a set of memory cells arranged in NAND strings and connected to a plurality of word lines, the plurality of word lines comprising a selected word line and unselected word lines; and a control circuit, the control circuit to perform verify tests for memory cells connected to the selected word line in one program loop, is configured to apply a plurality of verify voltages in turn to the selected word line, and during the application of each verify voltage, sense a conductive level of the memory cells connected to the selected word line and apply a variable voltage to a first adjacent word line of the selected word line, wherein the variable voltage is a first increasing function of the verify voltages. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method, comprising:
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applying verify voltage signal to memory cells connected to a selected word line; and during the applying of the verify voltage signal, sensing the memory cells connected to the selected word line and applying a voltage signal to a first adjacent word line of the selected word line, wherein the voltage signal applied to the first adjacent word line exceeds the verify voltage signal and steps up as the verify voltage signal steps up. - View Dependent Claims (14, 15, 16)
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17. An apparatus, comprising:
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a set of memory cells arranged in a NAND string, the set of memory cells comprising a selected memory cell and an adjacent memory cell; means for applying different verify voltages to the selected memory cell during verify tests of a program loop; and means for applying different voltages to the adjacent memory cell during the verify tests, when the different verify voltages are applied to the selected memory cell. - View Dependent Claims (18, 19, 20)
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Specification