Magnetic Memory Element With Perpendicular Anisotropy For Independent Writing And Reading
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Magnetic memory elements face challenges in independently designing writing and reading characteristics, leading to increased process complexity, reduced process margin, and larger cell area, as well as higher costs due to the need for multiple layers and precise adjustments in existing MRAM technologies.
Innovation Solution
A magnetic memory element structure featuring a magnetization free layer with perpendicular magnetic anisotropy, a response layer, a non-magnetic layer, and a reference layer, allowing for independent design of writing and reading characteristics without increasing the number of processes or cell area, by using ferromagnetic substances with perpendicular magnetic anisotropy for the free and response layers and a non-magnetic substance for the non-magnetic layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a magnetic field generated by wiring is used to switch magnetization direction, then writing speed is improved (one nanosecond or less), but writing current increases to several milliamperes and chip area increases
Solution Approach 1:
The patent replaces the magnetic field-based writing mechanism (which requires high current through peripheral wiring) with a spin transfer torque mechanism. A current is passed directly through the magnetic tunnel junction to reverse magnetization, substituting the mechanical/electromagnetic field generation system with a quantum mechanical spin transfer effect that operates at much lower currents.
Solution Approach 2:
The patent introduces a magnetic tunnel junction as an intermediary element between the current source and the magnetic storage layer. This junction enables efficient spin transfer torque by allowing spin-polarized electrons to pass through the tunnel barrier and transfer angular momentum to the magnetic moment, achieving magnetization reversal without requiring high-current peripheral wiring.
2Area of moving object
If element size is reduced for scaling, then integration density is improved, but writing current further increases in magnetic field-based methods
Solution Approach 1:
The patent replaces the magnetic field-based writing mechanism with spin transfer torque through a magnetic tunnel junction. This substitution eliminates the inverse relationship between element size and writing current, allowing scaling to smaller dimensions without increasing writing current requirements.
3Reliability
If multiple layers and precise adjustments are made to independently design writing and reading characteristics, then performance is improved, but process complexity increases and cell area increases
Solution Approach 1:
The patent employs a magnetic tunnel junction that serves multiple functions simultaneously: it acts as the reading element via magnetoresistance and as the writing element via spin transfer torque. This multi-functionality eliminates the need for separate writing and reading structures, reducing process complexity while maintaining independent optimization of writing and reading characteristics through material composition and thickness control.
Solution Approach 2:
The patent merges the writing and reading functions into a single magnetic tunnel junction structure. The same junction that provides magnetoresistance for reading also provides spin transfer torque for writing, combining previously separate functions into one integrated element that reduces overall device complexity.
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 enables independent optimization of writing and reading characteristics, reducing process complexity and costs while maintaining high performance, thereby achieving both satisfactory writing and reading characteristics with a wide process margin.
Implementation Method 1
a magnetization free layer with perpendicular magnetic anisotropy
Implementation Method 2
this invention relates to a magnetic memory element which uses domain wall motion
Implementation Method 3
the magnetoresistance which develops between the first magnetic layer (magnetization free layer) and the second magnetic layer (reference layer) is used
Data Source
AI summary
A disclosed magnetic memory element includes: a magnetization free layer formed of a ferromagnetic substance having perpendicular magnetic anisotropy; a response layer provided so as to be opposed to the magnetization free layer and formed of a ferromagnetic substance having perpendicular magnetic anisotropy; a non-magnetic layer provided so as to be opposed to the response layer on a side opposite to the magnetization free layer and formed of a non-magnetic substance; and a reference layer provided so as to be opposed to the non-magnetic layer on a side opposite to the response layer and formed of a ferromagnetic substance having perpendicular magnetic anisotropy. The magnetization free layer includes a first magnetization fixed region and a second magnetization fixed region which have magnetization fixed in directions antiparallel to each other, and a magnetization free region in which a magnetization direction is variable.