Magnetic Tunnel Junction Cell With Multiple Magnetic Domains
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Solution Overview
Problem
Traditional magnetic tunnel junction (MTJ) devices have limitations in increasing data density without expanding circuit area, as they typically store only one bit per cell, leading to increased manufacturing costs and wire-trace routing complexity.
Innovation Solution
The development of a magnetic tunnel junction cell that incorporates multiple independent magnetic domains, allowing a single cell to store up to four data bits by utilizing sidewalls and a bottom wall, enabling scalable storage density with process technology advancements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple MTJ structures are formed in a single MTJ device to increase data density, then storage density in X-Y direction is improved, but device complexity and wire-trace routing complexity increase
Solution Approach 1:
The free magnetic layer is divided into multiple independent magnetic domains separated by domain walls. Each domain can independently store a bit value, allowing multiple bits to be stored within a single MTJ cell structure. This segmentation enables increased storage density without requiring multiple separate MTJ devices or complex interconnections.
Solution Approach 2:
The patent extends magnetic domain storage from traditional planar 2D configuration to 3D structures including sidewalls and bottom surfaces. By utilizing vertical sidewalls and the bottom surface of the MTJ cell as additional dimensions for magnetic domain formation, the invention achieves multi-bit storage within a single cell footprint, dramatically increasing storage density without expanding the device footprint or requiring complex routing.
2Area of stationary object
If MTJ device size is reduced to increase data density, then area efficiency is improved, but manufacturing precision requirements increase due to critical dimension limitations
Solution Approach 1:
By utilizing vertical sidewalls and bottom surfaces in addition to the planar area, the invention effectively increases the storage volume without increasing the device footprint. This dimensional extension allows maintaining larger effective storage dimensions while keeping the critical planar dimensions small, thereby reducing the impact of critical dimension limitations on manufacturing precision.
3Quantity of substance
If multiple MTJ structures are stacked in Z-direction to increase data density, then storage capacity is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The free magnetic layer is segmented into multiple independent magnetic domains that can be independently controlled and accessed. This segmentation allows multiple bits to be stored within a single MTJ cell without requiring multiple stacked MTJ structures, thereby achieving increased storage capacity while avoiding the manufacturing complexity and cost associated with multi-layer stacking.
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 solution enables the storage of multiple bits per MTJ cell, increasing data density without expanding circuit area, and allows for independent writing and reading of data bits without affecting other domains, thus enhancing storage capacity and efficiency.
Implementation Method 1
a bit value is represented by a magnetic field induced in the free magnetic layer
Implementation Method 2
a free magnetic layer, where a bit value is represented by a magnetic field induced in the free magnetic layer
Implementation Method 3
a barrier layer (i.e., a tunneling oxide layer)
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
In a particular embodiment, a magnetic tunnel junction (MTJ) structure (100) is disclosed that includes an MTJ cell having multiple sidewalls (110, 112, 114) that extend substantially normal to a surface of a substrate (490). Each of the multiple sidewalls includes a free layer (106) to carry a unique magnetic domain. Each of the unique magnetic domains is adapted to store a digital value.