Abstract: A phase change memory cell has more than one memory region each being a narrowed region of phase change memory material extending between first and second electrodes. Each of the plurality of memory regions can be programmed to be in a low resistance state or a high resistance state by applying suitable programming conditions of current and/or voltage. The resistances of the high resistance states and the programming conditions to convert the high resistance states to the low resistance state are different in each of the plurality of memory regions.

Abstract: A memory device comprises an array of memory cells for storing data and a voltage application unit for applying voltages to the cells for writing data to the cells. Each memory cell has a first layer comprising copper in contact with a second layer comprising a chalcogenide material. The voltage application unit is arranged to write data by switching each cell between a first resistance state and a second, lower, resistance state. The voltage application unit is arranged to switch a cell to the first resistance state by applying a potential difference across the first and second layers such that the potential at the first layer is higher than the potential at the second layer by 0.5 volts or less. The voltage application unit is arranged to switch a cell to the second resistance state by applying a potential difference across the first and second layers such that the potential at the second layer is higher than the potential at the first layer by 0.5 volts or less.

Abstract: A phase change memory cell has more than one memory region (14,18) each being a narrowed region of phase change memory material (2) extending between first and second electrodes (4,6). Each of the plurality of memory regions (14, 18) can be programmed to be in a low resistance state or a high resistance state by applying suitable programming conditions of current and/or voltage. The resistances of the high resistance states and the programming conditions to convert the high resistance states to the low resistance state are different in each of the plurality of memory regions.

Abstract: A phase-change-memory cell is provided which comprises two insulated regions formed in a first phase-change material connected by a region formed in a second phase-change material. The crystallization temperature of the second phase-change material is below the crystallization temperature of the first phase-change material. By locally changing the material properties using a second PCM material, which switches phase at a lower temperature, a localized “hot spot” is obtained.

Abstract: A phase-change-material memory cell is provided. The cell comprises at least one patterned layer of a phase-change material, and is characterized in that this patterned layer comprises at least two regions having different resistivities. If the resistivity of the phase-change material is higher in a well-defined area with limited dimensions (“hot spot”) than outside this area, then, for a given current flow between the electrodes, advantageously more Joule heat will be generated within this area compared to the area of the phase-change material where the resistivity is lower.

Abstract: A memory device comprises an array of memory cells for storing data and a voltage application unit for applying voltages to the cells for writing data to the cells. Each memory cell has a first layer comprising copper in contact with a second layer comprising a chalcogenide material. The voltage application unit is arranged to write data by switching each cell between a first resistance state and a second, lower, resistance state. The voltage application unit is arranged to switch a cell to the first resistance state by applying a potential difference across the first and second layers such that the potential at the first layer is higher than the potential at the second layer by 0.5 volts or less. The voltage application unit is arranged to switch a cell to the second resistance state by applying a potential difference across the first and second layers such that the potential at the second layer is higher than the potential at the first layer by 0.5 volts or less.

Abstract: The present invention discloses a vertical phase-change-memory (PCM) cell, comprising a stack of a bottom electrode (5) contacting a first layer of phase change material (14), a dielectric layer (12) having an opening (13), a second layer of phase change material (6) in contact with the first layer of phase change material through the opening in the dielectric layer and a top electrode (7) contacting this second layer of phase change material.

Abstract: A phase-change-material memory cell is provided. The cell comprises at least one patterned layer of a phase-change material, and is characterized in that this patterned layer comprises at least two regions having different resistivities. If the resistivity of the phase-change material is higher in a well-defined area with limited dimensions (“hot spot”) than outside this area, then, for a given current flow between the electrodes, advantageously more Joule heat will be generated within this area compared to the area of the phase-change material where the resistivity is lower.

Abstract: The present invention discloses a vertical phase-change-memory (PCM) cell, comprising a stack of a bottom electrode (5) contacting a first layer of phase change material (14), a dielectric layer (12) having an opening (13), a second layer of phase change material (6) in contact with the first layer of phase change material through the opening in the dielectric layer and a top electrode (7) contacting this second layer of phase change material.

Abstract: A phase-change-memory cell is provided which comprises two insulated regions formed in a first phase-change material connected by a region formed in a second phase-change material. The crystallization temperature of the second phase-change material is below the crystallization temperature of the first phase-change material. By locally changing the material properties using a second PCM material, which switches phase at a lower temperature, a localized “hot spot” is obtained.