Magnetic Random Access Memory Cell Segmentation for Write Current Control
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Solution Overview
Problem
Magnetic random access memory (MRAM) write properties and circuit complexity increase with miniaturization, as the size of memory cells decreases, leading to different write properties and control complexities for switching directions ('1' to '0' and '0' to '1') in spin transfer processes.
Innovation Solution
A magnetic random access memory with a spin transfer process that includes a plurality of magnetic memory cells, a current supply unit, and a control unit, featuring antiferromagnetically-coupled magnetic material layers and spin control layers to supply spin electrons independently of write data, allowing similar write properties and circuit operation regardless of stored data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If memory cell size is reduced to increase memory capacity, then memory capacity increases, but write current increases and write properties deteriorate
Solution Approach 1:
The magnetic memory cell is segmented into multiple magnetic layers (pinned layer, free layer, and intermediate magnetic layer) with distinct functions. The intermediate layer is further segmented into multiple sub-layers with different magnetization directions, allowing independent control of spin electron supply. This segmentation enables the write current to be distributed and controlled more efficiently, reducing the peak current required for magnetization switching while maintaining high memory capacity through miniaturization.
2Quantity of substance
If memory cell size is reduced to increase memory capacity, then memory capacity increases, but device complexity increases due to different write properties for different switching directions
Solution Approach 1:
Different regions of the magnetic memory cell are assigned different local properties: the pinned layer has fixed magnetization direction, the free layer has variable magnetization direction, and the intermediate layer has multiple sub-layers with different magnetization directions. This local quality differentiation allows the cell to achieve uniform write properties for both '0' to '1' and '1' to '0' transitions, simplifying the control circuit design while enabling high-density memory capacity.
Solution Approach 2:
The invention changes the magnetization direction parameters of the intermediate magnetic layer sub-layers to create symmetric write characteristics. By adjusting the magnetization directions of the intermediate layer sub-layers to be opposite to each other, the write current requirements for switching between '0' and '1' states become equal, eliminating the need for complex direction-dependent control circuits and enabling scalable high-capacity memory designs.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables consistent write properties and simplified circuit operation for both '1' to '0' and '0' to '1' transitions, reducing complexity and increasing memory capacity by maintaining similar write characteristics across different data states.
Implementation Method 1
A magnetic random access memory of a spin transfer process is provided
Implementation Method 2
Grollier et al., 'Spin-polarized current induced switching in Co/Cu/Co pillars'
Implementation Method 3
at least one intermediate magnetic layer, and a non-magnetic conductor layer which sandwiched between the first magnetic material layer and the second magnetic material layer
Implementation Method 4
an element is known, which indicates a magnetic resistive effect such as an AMR (Anisotropic Magneto-Resistance) effect, a GMR (Giant Magnet-Resistance) effect and a TMR (Tunnel Magneto-Resistance) effect
Data Source
AI summary
A magnetic random access memory of a spin transfer process, includes a plurality of magnetic memory cells 10, a current supply unit 43+20+30 and a control unit 41. The current supply unit 43+20+30 supplies a write current to the magnetic memory cell 10. The control unit controls a supply of the write current supplied by the current supply unit 43+20+30 on the basis of a write data. Each magnetic memory cell 10 includes a magnetic material storage layer which stores a data by using a magnetization state, and at least one spin control layer which supplies spin electrons to the magnetic material storage layer on the basis of a same control principle independently of the write data, on the basis of the write current.