Multilevel Variable Resistance Memory Cell Utilizing Crystalline Programming States
First Claim
1. A method of programming a variable resistance material comprising:
- providing a variable resistance material;
a first programming step, said first programming step transforming said variable resistance material to a first crystalline programming state, said first crystalline programming state having a first resistance;
a second programming step, said second programming step transforming said variable resistance material to a second crystalline programming state, said second crystalline programming state having a second resistance; and
a third programming step, said third programming step transforming said variable resistance material to a third programming state, said third programming state having a third resistance.
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Abstract
A method of programming an electrical variable resistance memory device. When applied to variable resistance memory devices that incorporate a phase-change material as the active material, the method utilizes a plurality of crystalline programming states. The crystalline programming states are distinguishable on the basis of resistance, where the resistance values of the different states are stable with time and exhibit little or no drift. As a result, the programming scheme is particularly suited to multilevel memory applications. The crystalline programming states may be achieved by stabilizing crystalline phases that adopt different crystallographic structures or by stabilizing crystalline phases that include mixtures of two or more distinct crystallographic structures that vary in the relative proportions of the different crystallographic structures. The programming scheme incorporates at least two crystalline programming states and further includes at least a third programming state that may be a crystalline, amorphous or mixed crystalline-amorphous state.
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Citations
55 Claims
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1. A method of programming a variable resistance material comprising:
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providing a variable resistance material; a first programming step, said first programming step transforming said variable resistance material to a first crystalline programming state, said first crystalline programming state having a first resistance; a second programming step, said second programming step transforming said variable resistance material to a second crystalline programming state, said second crystalline programming state having a second resistance; and a third programming step, said third programming step transforming said variable resistance material to a third programming state, said third programming state having a third resistance. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50)
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51. A method of programming a variable resistance material comprising:
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providing a variable resistance material; a first programming step, said first programming step transforming said variable resistance material to a first crystalline programming state, said first crystalline programming state including a first crystalline phase and a second crystalline phase, said first crystalline programming state having a first resistance; and a second programming step, said second programming step transforming said variable resistance material to a second crystalline programming state, said second crystalline programming state including a third crystalline phase and a fourth crystalline phase, said second crystalline programming state having a second resistance. - View Dependent Claims (52, 53, 54, 55)
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Specification