Phase change device having two or more substantial amorphous regions in high resistance state
First Claim
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1. A memory device comprising:
- a memory cell comprising a first electrode, a second electrode, and phase change material having first and second active regions arranged in series along an inter-electrode current path between the first electrode and the second electrode;
bias circuitry adapted to apply bias arrangements to the memory cell to store a bit, the bias arrangements including;
a first bias arrangement adapted to establish a high resistance state in the memory cell by inducing a high resistance condition in both the first and second active regions to store a first value of the bit in the memory cell, the high resistance state having a minimum resistance indicating that at least one of the active regions is in the high resistance condition, anda second bias arrangement adapted to establish a low resistance state in the memory cell by inducing a low resistance condition in both the first and second active regions to store a second value of the bit in the memory cell, the low resistance state having a maximum resistance indicating that both the first and second active regions are in the low resistance condition; and
sense circuitry to sense the value of the bit in the memory cell by determining whether the memory cell has a resistance corresponding to the low resistance state or to the high resistance state.
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Abstract
Memory devices are described herein along with method for operating the memory device. A memory cell as described herein includes a first electrode and a second electrode. The memory cell also comprises phase change material having first and second active regions arranged in series along an inter-electrode current path between the first and second electrode.
340 Citations
26 Claims
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1. A memory device comprising:
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a memory cell comprising a first electrode, a second electrode, and phase change material having first and second active regions arranged in series along an inter-electrode current path between the first electrode and the second electrode; bias circuitry adapted to apply bias arrangements to the memory cell to store a bit, the bias arrangements including; a first bias arrangement adapted to establish a high resistance state in the memory cell by inducing a high resistance condition in both the first and second active regions to store a first value of the bit in the memory cell, the high resistance state having a minimum resistance indicating that at least one of the active regions is in the high resistance condition, and a second bias arrangement adapted to establish a low resistance state in the memory cell by inducing a low resistance condition in both the first and second active regions to store a second value of the bit in the memory cell, the low resistance state having a maximum resistance indicating that both the first and second active regions are in the low resistance condition; and sense circuitry to sense the value of the bit in the memory cell by determining whether the memory cell has a resistance corresponding to the low resistance state or to the high resistance state. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A method for operating a memory cell comprising a first electrode, a second electrode, and phase change material having first and second active regions arranged in series along an inter-electrode current path between the first electrode and the second electrode, the method comprising:
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determining a data value of a bit to be stored in the memory cell; applying a first bias arrangement to the memory cell if the data value is a first value, the first bias arrangement adapted to establish a high resistance state in the memory cell by inducing a high resistance condition in both the first and second active regions to store the first value of the bit, the high resistance state having a minimum resistance indicating that at least one of the active regions is in the high resistance condition; applying a second bias arrangement to the memory cell if the data value is a second value, the second bias arrangement adapted to establish a low resistance state in the memory cell by inducing a low resistance condition in both the first and second active regions to store the second value of the bit, the low resistance state having a maximum resistance indicating that both the first and second active regions are in the low resistance state; and determining the data value of the bit stored in the memory cell by determining whether the memory cell has a resistance corresponding to the low resistance state or to the high resistance state. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26)
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Specification