No assignee for this patent application has been made.
News editors obtained the following quote from the background information supplied by the inventors: "Fast growth of the pervasive computing and handheld/communication industry generates exploding demand for high capacity nonvolatile solid-state data storage devices. It is believed that nonvolatile memories, especially flash memory, will replace DRAM to occupy the biggest share of memory market. However, flash memory has several drawbacks such as slow access speed (.about.ms write and .about.50-100 ns read), limited endurance (.about.10.sup.3-10.sup.4 programming cycles), and the integration difficulty in system-on-chip (SoC). Flash memory (NAND or NOR) also faces significant scaling problems at 32 nm node and beyond.
"Magnetic Random Access Memory (MRAM) is another promising candidate for future nonvolatile and universal memory. MRAM features non-volatility, fast writing/reading speed (10.sup.15cycles) and zero standby power. The basic component of MRAM is a magnetic tunneling junction (MTJ). Data storage is realized by switching the resistance of MTJ between a high-resistance state and a low-resistance state. MRAM switches the MTJ resistance by using a current induced magnetic field to switch the magnetization of MTJ. As the MTJ size shrinks, the switching magnetic field amplitude increases and the switching variation becomes severer. Hence, the incurred high power consumption limits the scaling of conventional MRAM.
"A write mechanism, which is based upon spin polarization current induced magnetization switching, was introduced to the MRAM design. This new MRAM design, called Spin-Transfer Torque RAM (STRAM), uses a (bidirectional) current through the MTJ to realize the resistance switching. Therefore, the switching mechanism of STRAM is constrained locally and STRAM is believed to have a better scaling property than the conventional MRAM.
"However, a number of yield-limiting factors must be overcome before MRAM enters the production stage. One concern in MRAM design is the thickness tradeoff between of the barrier layer of the cell. A thicker barrier layer improves the readability of the MRAM cell but also increases the switching voltage requirement since it is proportional to the thickness of the barrier layer. In addition, high operating voltages limit the flexibility of system integration and increase the size of the select device (e.g., transistor) for the MRAM."
As a supplement to the background information on this patent application, VerticalNews correspondents also obtained the inventors' summary information for this patent application: "The present disclosure relates to a spin-transfer torque memory unit with separate read and write paths. In particular, the present disclosure relates to a magnetic memory unit that provides a lateral spin torque write and a vertical magnetic tunnel junction read.
"In one particular embodiment, a magnetic memory unit includes a ferromagnetic strip having a first end portion with a first magnetization orientation, an opposing second end portion with a second magnetization orientation, and a middle portion between the first end portion and the second end portion, the middle portion having a free magnetization orientation. The first magnetization orientation opposes the second magnetization orientation. A tunneling barrier separates a magnetic reference layer from the middle portion forming a magnetic tunnel junction. A bit line is electrically coupled to the second end portion. A source line is electrically coupled to the first end portion and a read line is electrically coupled to the magnetic tunnel junction.
"In another particular embodiment, a spin-transfer torque memory unit includes a ferromagnetic strip having a first portion and an opposing second portion separated from each other. The ferromagnetic strip has a free magnetization orientation. A tunneling barrier separates a first magnetic reference layer from the first portion of the ferromagnetic strip and forming a magnetic tunnel junction. A conductive and non-ferromagnetic layer separates a second magnetic reference layer from the second portion of the ferromagnetic strip and forming a spin valve. A bit line is electrically coupled to the spin valve. A source line is electrically coupled to the ferromagnetic strip and a read line is electrically coupled to the magnetic tunnel junction.
"These and various other features and advantages will be apparent from a reading of the following detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
"The disclosure may be more completely understood in consideration of the following detailed description of various embodiments of the disclosure in connection with the accompanying drawings, in which:
"FIG. 1 is a cross-sectional schematic diagram of an illustrative magnetic tunneling junction (MTJ) in the low resistance state;
"FIG. 2 is a cross-sectional schematic diagram of the illustrative MTJ in the high resistance state;
"FIG. 3 is a schematic diagram of an illustrative spin-transfer torque memory unit having separate read and write paths;
"FIG. 4 is a schematic top plan view one illustrative configuration of the spin-transfer torque memory unit shown in FIG. 3;
"FIG. 5 is a schematic top plan view of another illustrative configuration of the spin-transfer torque memory unit shown in FIG. 3;
"FIG. 6 is a schematic diagram of another illustrative spin-transfer torque memory unit having separate read and write paths;
"FIG. 7 is a schematic top plan view one illustrative configuration of the spin-transfer torque memory unit shown in FIGS. 6; and
"FIG. 8 is a schematic top plan view of another illustrative configuration of the spin-transfer torque memory unit shown in FIG. 6.
"The figures are not necessarily to scale. Like numbers used in the figures refer to like components. However, it will be understood that the use of a number to refer to a component in a given figure is not intended to limit the component in another figure labeled with the same number."
For additional information on this patent application, see: Lu, Yong; Liu, Hongyue; Gao, Zheng; Jin, Insik; Dimitrov, Dimitar V. Magnetic Memory with Separate Read and Write Paths. Filed
Keywords for this news article include: Patents, Information Technology, Information and
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