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US 7,679,953 B2Granted
Calibration system for writing and reading multiple states into phase change memory
AssigneeMarvell World Trade Ltd.
InventorPantas Sutardja
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Abstract
A memory system includes phase change memory cells. A control module causes one of the phase change memory cells to be written using a write parameter, causes a resistance value of the one of the phase change memory cells to be read back, adjusts the write parameter, and causes the writing, reading and adjusting to be repeated until the resistance value is within a predetermined range of a target resistance value.
Claims19
A memory system, comprising:
- phase change memory cells;
- and
- a control module configured to
- apply a reset pulse to one of the phase change memory cells, the reset pulse heating the one of the phase change memory cells above a pre-determined temperature and permitting the one of the phase change memory cells to quickly cool,
- cause the one of the phase change memory cells to be written using a write parameter,
- cause a resistance value of the one of the phase change memory cells to be read back,
- adjust the write parameter, and
- cause the writing, reading and adjusting to be repeated until the resistance value is within a predetermined range of a target resistance value,
- wherein adjusting the write parameter includes
- varying a temperature applied to the one of the phase change memory cells, wherein an amplitude and a duration of a write current pulse controls the temperature applied to the one of the phase change memory cells, and
- varying a crystallization time of the one of the phase change memory cells.
8 more elements
A method of writing data to a first phase change memory cell of a plurality of phase change memory cells, the method comprising:
- applying a reset pulse to the first phase change memory cell, the reset pulse heating the first phase change memory cell above a pre-determined temperature and permitting the first phase change memory cell to quickly cool,
- writing to the first phase change memory cell using a write parameter;
- reading back a resistance value of the first phase change memory cell;
- adjusting the write parameter, wherein the adjusting the write parameter includes
- varying a temperature applied to the first phase change memory cell, wherein an amplitude and a duration of a write current pulse controls the temperature applied to the first phase change memory cell, and
- varying a crystallization time of the first phase change memory cell;
- and
- repeating said writing, said reading, and said adjusting until the resistance value is within a predetermined range of a target resistance value.
5 more elements
Dependencies are inferred from the claim text.