NON-VOLATILE SEMICONDUCTOR MEMORY DEVICE
First Claim
1. A non-volatile semiconductor memory device comprising;
- a semiconductor substrate;
a memory string stacked above the semiconductor substrate and comprising a plurality of memory cells connected in series;
a drain-side select transistor connected to a first end of the memory string;
a source-side select transistor connected to a second end of the memory string;
a plurality of word lines connected to the memory cell;
a plurality of bit lines connected to the drain-side select transistor;
a source line connected to the source-side select transistor; and
a control circuit configured to control a voltage supplied to the drain-side select transistor, the source-side select transistor, the word lines, and the bit lines,the control circuit being capable of performing a data variation determination operation of determining whether a plurality of memory cells connected to a selected word line each have a threshold voltage equal to or less than a certain value, and whether the number of memory cells where data variation has occurred is not less than a certain number.
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Accused Products
Abstract
A control circuit performs a read operation of reading data held in a memory-cell by supplying a selected word-line with a read voltage that is a voltage between the lower limit and the upper limit of a plurality of threshold-voltage distributions provided to the memory-cell. The control circuit also performs a verify operation of determining whether a write operation is completed by supplying a selected word-line with a verify voltage higher than the read voltage to read the memory cell. The control circuit then performs a data variation determination operation of determining whether the memory-cells connected to a selected word-line each have a threshold voltage equal to or less than a certain value to determine, from among the plurality of memory cells connected to the selected word-line, whether the number of memory cells where data variation has occurred is not less than a certain number.
31 Citations
20 Claims
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1. A non-volatile semiconductor memory device comprising;
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a semiconductor substrate; a memory string stacked above the semiconductor substrate and comprising a plurality of memory cells connected in series; a drain-side select transistor connected to a first end of the memory string; a source-side select transistor connected to a second end of the memory string; a plurality of word lines connected to the memory cell; a plurality of bit lines connected to the drain-side select transistor; a source line connected to the source-side select transistor; and a control circuit configured to control a voltage supplied to the drain-side select transistor, the source-side select transistor, the word lines, and the bit lines, the control circuit being capable of performing a data variation determination operation of determining whether a plurality of memory cells connected to a selected word line each have a threshold voltage equal to or less than a certain value, and whether the number of memory cells where data variation has occurred is not less than a certain number. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A method of controlling a non-volatile semiconductor memory device,
the non-volatile semiconductor memory device comprising a semiconductor substrate, a memory string extending in the vertical direction with respect to the semiconductor substrate and comprising a plurality of memory cells connected in series, a drain-side select transistor connected to a first end of the memory string, a source-side select transistor connected to a second end of the memory string, a plurality of word lines connected to the memory cell, a plurality of bit lines connected to the drain-side select transistor, and a source line connected to the source-side select transistor, the method comprising: -
executing a data variation determination operation of determining whether variation has occurred in the upper limit or lower limit of a plurality of threshold voltage distributions in each of the memory cells by supplying a first voltage lower than a read voltage and a second voltage higher than the first voltage to a selected word line to read the memory cell; and executing, when the data variation determination operation determines that the memory cells along the selected word line have a certain number of data variations or more, an additional write operation of writing to return the threshold voltage distributions of the memory cells along the selected word line to a normal state. - View Dependent Claims (19, 20)
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Specification