Nonvolatile semiconductor memory device and method of writing data into the same
AssigneeNEC Electronics Corporation
InventorHiroshi SUGAWARA
Life of this patent
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Abstract
In a nonvolatile semiconductor memory device, a memory cell array has a plurality of nonvolatile memory cells arranged in a matrix. A selecting section selects as selection memory cells, at least two of the plurality of nonvolatile memory cells from the memory cell array. A write section applies to the selection memory cells, a gate voltage which increases step by step, until a threshold voltage of each of the selection memory cells reaches a target threshold voltage, such that the threshold voltage increases step-by-step.
Claims19
A nonvolatile semiconductor memory device comprising:
- a memory cell array configured to have a plurality of nonvolatile memory cells arranged in a matrix;
- a selecting section configured to select as selection memory cells, at least two of said plurality of nonvolatile memory cells from said memory cell array;
- and
- a write section configured to apply to said selection memory cells, a gate voltage which increases step by step, until a threshold voltage of each of said selection memory cells reaches a target threshold voltage, such that said threshold voltage increases step-by-step.
A method of writing data in a nonvolatile semiconductor memory device, comprising:
- selecting as selection memory cells, at least two of a plurality of nonvolatile memory cells arranged in a matrix from a memory cell array;
- and
- writing a target threshold voltage into each of said selection memory cells by increasing a threshold voltage of said selection memory cell step-by-step while applying a gate voltage increasing step by step to said selection memory cell.
A method of writing data into a number of memory cells of a nonvolatile semiconductor memory device at a same time, said device comprising a boosting circuit which can supply a current for a memory cell, but cannot supply a current for a number of memory cells at the same time, comprising:
- selecting the number of memory cells;
- setting a gate voltage of said selected memory cells to a first voltage level;
- writing a first threshold voltage into said selected memory cells by using said gate voltage of said first voltage level;
- changing said gate voltage of said selected memory cells from said first voltage level into a second voltage level;
- and
- writing a second threshold voltage higher than said first threshold voltage into said selected memory cells by using said gate voltage of said second voltage level.
Dependencies are inferred from the claim text.