Magnetic Memory Device Stray Field Management
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Solution Overview
Problem
As MRAM is miniaturized, the proximity of adjacent MTJ elements leads to adverse effects from stray fields, degrading their characteristics and affecting data retention and operation reliability.
Innovation Solution
The implementation of a magnetic memory device with adjacent MTJ elements having antiparallel magnetization directions and the use of conductive or non-conductive yokes between them to manage stray fields, either by forming a closed loop or by attracting magnetic forces, thereby reducing the impact on storage and reference layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If MRAM is miniaturized to increase storage capacity, then the quantity of memory elements increases, but the characteristics of adjacent MTJ elements are degraded due to stray fields
Solution Approach 1:
A non-magnetic layer is introduced as an intermediary between adjacent MTJ elements. This layer acts as a magnetic shield that blocks stray magnetic fields from one MTJ element from affecting adjacent elements, thereby maintaining data retention characteristics even when elements are miniaturized and placed closer together
Solution Approach 2:
The patent converts the harmful stray magnetic fields into a beneficial configuration by setting alternating magnetization directions in adjacent MTJ elements. This creates a pattern where stray fields from one element are counteracted by opposing fields from neighboring elements, reducing net interference while enabling higher density
2Quantity of substance
If the distance between adjacent MTJ elements is decreased to increase density, then the storage capacity increases, but the characteristics of MTJ elements vary under stray field effects
Solution Approach 1:
The non-magnetic layer serves as a physical barrier and magnetic shield between closely spaced MTJ elements, preventing stray fields from causing characteristic variations even when elements are positioned at minimal distances for high density
Solution Approach 2:
Each MTJ element is given a specific local magnetization direction (alternating between adjacent elements), creating localized magnetic configurations that are stable and predictable. This local control of magnetic properties ensures consistent characteristics across the entire memory array despite high density
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 configuration enhances the stability of memory operations, including write, read, and data retention characteristics by minimizing the effects of stray fields, thereby improving the reliability and capacity of MRAM.
Implementation Method 1
magnetoresistive elements utilizing a TMR (tunneling magnetoresistive) effect are used as memory cells that store information
Implementation Method 2
A third magnetic layer in the first and second magnetoresistive elements are provided between the first magnetic layer and the fourth magnetic layer... enhances the stability of memory operations... by minimizing the effects of stray fields
Data Source
AI summary
According to one embodiment, the magnetic memory device includes a first magnetoresistive element and a second magnetoresistive element which are adjacent to each other. Each of the first and second magnetoresistive elements includes a first magnetic layer, a first non-magnetic later on the first magnetic layer, a second magnetic layer on the first non-magnetic layer, a second non-magnetic layer on the second magnetic layer, and a third magnetic layer on the second non-magnetic layer. Furthermore, the magnetic memory device further includes a fourth magnetic layer being in contact with the first and second magnetoresistive elements or in contact with conductive layers on the first and second magnetoresistive elements.