Magnetoresistive Memory Device Hexagonal MTJ Stacking
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Solution Overview
Problem
Current magnetoresistive memory devices using magnetic tunnel junction (MTJ) elements face challenges in achieving high density and reducing cell size due to limitations in arranging MTJ elements in a way that maximizes space efficiency and density without increasing the pitch between elements.
Innovation Solution
The implementation of a magnetoresistive memory device structure where MTJ elements are arranged in a hexagonal close-packed or square grid structure across multiple layers, allowing for increased density by optimizing the pitch between elements while maintaining wide spaces within each layer, achieved through specific wiring and contact arrangements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If MTJ elements are arranged in conventional square grid structure, then manufacturing is simpler, but density is lower and cell size is larger
Solution Approach 1:
The patent transitions from a conventional two-dimensional square grid arrangement to a three-dimensional stacked architecture where MTJ elements are arranged in multiple layers. This vertical stacking enables higher density by utilizing the third dimension (height) rather than only expanding in the planar dimensions, thereby increasing the number of MTJ elements per unit area without proportionally increasing wiring complexity.
Solution Approach 2:
The patent divides the MTJ element array into multiple independent layers, with each layer containing a subset of MTJ elements. This segmentation allows for modular manufacturing and independent optimization of each layer, reducing the overall complexity of wiring and contact arrangements while achieving higher total density through the combination of multiple layers.
2Quantity of substance
If pitch between MTJ elements is reduced to increase density, then more elements fit in unit area, but manufacturing precision requirements increase
Solution Approach 1:
By stacking MTJ elements in multiple vertical layers, the patent effectively increases the usable area for element placement without reducing the pitch within individual layers. This approach allows maintaining larger, more manufacturable pitch dimensions while achieving higher overall density through the multiplication of elements across multiple layers.
3Quantity of substance
If MTJ elements are arranged to maximize space efficiency, then density increases, but cell size reduction is limited
Solution Approach 1:
The patent achieves cell size reduction by distributing MTJ elements across multiple vertical layers rather than packing them densely in a single plane. This three-dimensional arrangement allows each memory cell to occupy a smaller footprint area while the overall cell volume is efficiently utilized through vertical stacking, thereby reducing the effective cell size in the planar dimension.
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
This approach enables a higher density of MTJ elements per unit area with reduced cell size, as demonstrated by calculations showing increased MTJ element density and reduced pitch requirements, facilitating a high-density cell structure.
Implementation Method 1
In a spin injection MRAM using spin injection magnetization inversion technology, data is written to an MTJ element by energizing the MTJ element in a direction perpendicular to a film surface of the MTJ element.
Data Source
AI summary
According to one embodiment, a magnetoresistive memory device, includes first wirings arranged parallel to each other in or on a substrate, second wirings arranged parallel to each other above the substrate to cross the first wirings when viewed in a direction perpendicular to a surface of the substrate, and magnetoresistive elements provided corresponding to intersections of the first and second wirings, respectively, and divided into layers.