摘要:
Briefly, in accordance with an embodiment of the invention, an apparatus and method to provide refreshing of a memory cell of a phase change memory device is provided. The method includes determining whether a storage level of a phase change memory cell is within a predetermined margin from a resistance threshold. In response to the determination, the cell is selectively written. The apparatus includes a circuit to: determine whether a storage level of a phase change memory cell is within a predefined margin from a resistance threshold level; and in response to the determination, selectively write to the cell.
摘要:
A voltage sensing circuit is used to rapidly pull up a high potential node of a reference array to a value of a high potential source reduced by a threshold voltage (V.sub.CC -V.sub.T). During an enable cycle, the high potential node is precharged to a potential of V.sub.CC -V.sub.T, which turns on a transistor gated to the V.sub.CC potential. This pulls the high potential node as rapidly as possible to a high level in order to speed up the sensing process. A potential maintenance circuit provides sufficient current from the high potential source to maintain a desired potential at the high potential node.
摘要:
A memory may be implemented with a stable chalcogenide glass which is defined as a generally amorphous chalcogenide material that does not change to a generally crystalline phase when exposed to 200° C. for 30 minutes or less. Different states may be programmed by changing the threshold voltage of the material. The threshold voltage may be changed with pulses of different amplitude and/or different pulse fall times. Reading may be done using a reference level between the threshold voltages of the two different states. A separate access device is generally not needed.
摘要:
A read bias scheme may be used for phase change memories including a chalcogenide access device and a chalcogenide memory element. Through an appropriate read bias scheme, desirable read margin can be achieved. This may result in better yield, higher reliability, and ultimately lower costs in some cases.
摘要:
A memory may be implemented with a stable chalcogenide glass which is defined as a generally amorphous chalcogenide material that does not change to a generally crystalline phase when exposed to 200° C. for 30 minutes or less. Different states may be programmed by changing the threshold voltage of the material. The threshold voltage may be changed with pulses of different amplitude and/or different pulse fall times. Reading may be done using a reference level between the threshold voltages of the two different states. A separate access device is generally not needed.
摘要:
Briefly, in accordance with an embodiment of the invention, a memory is provided. The memory may include a memory element and a first access device coupled to the memory element, wherein the first access device comprises a first chalcogenide material. The memory may further include a second access device coupled to the first access device, wherein the second access device comprises a second chalcogenide material.
摘要:
An improved CMOS fabrication process which uses separate masking steps to pattern N-channel and P-channel transistor gates from a single layer of conductively-doped polycrystalline silicon (poly). The object of the improved process is to reduce the cost and improve the reliability and manufacturability of CMOS devices by dramatically reducing the number of photomasking steps required to fabricate transistors. By processing N-channel and P-channel devices separately, the number of photomasking steps required to fabricate complete CMOS circuitry in a single-polysilicon-layer or single-metal layer process can be reduced from eleven to eight. Starting with a substrate of P-type material, N-channel devices are formed first, with unetched poly left in the future P-channel regions until N-channel processing is complete. The improved CMOS process provides the following advantages over conventional process technology. Use of a masked high-energy punch-through implant for N-channel devices is not required; individual optimization of N-channel and P-channel transistors is made possible; a lightly-doped drain (LDD) design for both N-channel and P-channel transistors is readily implemented; source/drain-to-gate offset may be changed independently for N-channel and P-channel devices; and N-channel and P-channel transistors can be independently controlled and optimized for best LDD performance and reliability.
摘要:
A memory array (e.g., DRAM) is provided with a potential maintenance circuit which provides sufficient current to maintain a high potential node of the memory array at a predetermined potential. The potential maintenance circuit is gated ON after receipt of a clock signal and gated OFF at the predetermined potential. This permits the high voltage node to be maintained, while reducing current requirements. The invention is particularly useful when used in conjunction with a circuit which rapidly pulls up the high node to a value of V.sub.CC -V.sub.T (where VT is a threshold voltage of a transistor).
摘要:
A memory may be implemented with a stable chalcogenide glass which is defined as a generally amorphous chalcogenide material that does not change to a generally crystalline phase when exposed to 200° C. for 30 minutes or less. Different states may be programmed by changing the threshold voltage of the material. The threshold voltage may be changed with pulses of different amplitude and/or different pulse fall times. Reading may be done using a reference level between the threshold voltages of the two different states. A separate access device is generally not needed.
摘要:
Briefly, in accordance with an embodiment of the invention, a method and system to program a memory material is provided. The method may include applying three signals having different durations and different amplitudes to a memory material to program the memory material to a predetermined state.