Nonvolatile storage device and operating method thereof
AssigneeNEC Electronics Corporation
InventorsTakeshi Okazawa, Yuukoh Katoh
Life of this patent
Estimating the term…
Abstract
A nonvolatile storage device and method of operation capable of preventing opens in a word line and/or bit line that may result from electromigration is disclosed. A nonvolatile storage device according to an embodiment may include a number of magnetic resistance elements provided at intersections of word lines and bit lines, a word line control circuit for selecting one word line and supplying a write current thereto in a write operation, and a bit line control circuit for selecting one bit line and supplying a write current thereto. A word line control circuit can provide a bidirectional write current to a word line.
Claims23
A nonvolatile storage device, comprising:
- a plurality of word lines;
- a plurality of bit lines;
- a plurality of magnetic resistance elements provided at intersections of the word lines and bit lines;
- a word line control circuit that selects one of the word lines in a write operation and supplies a bidirectional word line write current to the selected word line;
- and
- a bit line control circuit that selects one of the bit lines in the write operation and supplies a bit line write current to the selected bit line
- wherein in the write operation, the word line control circuit provides the word line write current in one direction and then in a reverse direction.
A nonvolatile storage device, comprising:
- a plurality of word lines;
- a plurality of bit lines;
- a plurality of magnetic resistance elements provided at intersections of the word lines and bit lines;
- a word line control circuit that selects one of the word lines and supplies a word line write current to the selected word line in a write operation, the word line control circuit reversing the word line write current based on at least one previous word line write current direction;
- and
- a bit line control circuit that selects one of the bit lines in the write operation and supplies a bit line write current to the selected bit line.
The nonvolatile storage device of 10, wherein:
- the word line control circuit includes counter that counts the number of times that a write current of one direction is supplied to the word line, and when the count reaches a predetermined value, resets the counter count and reverses the word line write current direction for the word line.
The nonvolatile storage device of 10, wherein:
- the bit line control circuit includes a counter that adds or subtracts a count value according to a direction of a bit line write current, and when the absolute value of the count reaches a predetermined value, a bit line current is provided to bring the count value toward zero.
The nenvolatile storage device of 10, wherein:
- the word line control circuit stores a direction of a word line write current supplied to a word line, and reverses the word line write current direction in a next write operation.
The nonvolatile storage device of 10, further including:
- a switching device corresponding to each word line that selectively connects each word line to a predetermined supply potential.
A method of operating a nonvolatile storage device, comprising the steps of:
- supplying a bidirectional word line write current to a word line selected by a word line control circuit when writing data to a magnetic resistance element formed at an intersection of the word line and bit line;
- and
- supplying a bit line write current to the bit line, the bit line being selected by a bit line control circuit
- wherein the step of supplying the bidirectional word line write current includes supplying the word line with a word line write current in one direction and then supplying the word line write current in the reverse direction in the same write operation.
A method of operating a nonvolatile storage device, comprising the steps of:
- switching a direction of a word line write current in a write operation based on at least one previous word line write current direction when writing data to a magnetic resistance element formed at an intersection of the word line and a bit line;
- and
- supplying a bit line write current to the bit line, the bit line being selected by a bit line control circuit.
Dependencies are inferred from the claim text.