Magnetoresistive Element Boron Gradient Write Current
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Solution Overview
Problem
Spin transfer torque magnetic random access memories (STT-MRAMs) face challenges in reducing write current for magnetic tunnel junction (MTJ) elements, which is essential for lowering power consumption, as existing perpendicular magnetization MTJ elements still require significant write currents to switch magnetization directions.
Innovation Solution
A magnetoresistive element with a multilayer structure is developed, including a nitrogen-containing base layer, a storage layer with varying boron concentrations, and an intermediate layer, which reduces the write current by optimizing the boron concentration and layer thickness to minimize spin pumping effects and improve wettability, thereby reducing the Gilbert damping constant and write current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If perpendicular magnetization MTJ elements are employed to reduce write current, then power consumption is reduced, but the write current remains significant and switching difficulty persists
Solution Approach 1:
The patent applies local quality by creating a gradient in boron concentration within the storage layer. The boron concentration varies from the first interface with the base layer to the second interface with the reference layer, with a specific concentration range (10-30 atomic %) optimized at different positions. This spatial variation in composition locally optimizes magnetic anisotropy and damping characteristics, enabling reduced write current while maintaining switching ease.
Solution Approach 2:
The patent changes physical and chemical parameters of the storage layer, specifically the boron concentration parameter. By controlling boron concentration to be in the range of 10-30 atomic % at the first interface and varying it through the layer thickness, the patent optimizes the Gilbert damping constant and perpendicular magnetic anisotropy energy density. This parameter optimization enables lower write current operation while maintaining magnetization switching capability.
2Use of energy by moving object
If boron concentration is increased to improve wettability and reduce Gilbert damping constant, then write current is reduced, but layer composition control complexity increases
Solution Approach 1:
The patent specifies precise parameter ranges for boron concentration (10-30 atomic %) and layer thickness (0.5-5 nm) to optimize the balance between write current reduction and manufacturing feasibility. These parameter specifications enable controlled variation in composition that achieves the desired Gilbert damping constant reduction while remaining compatible with standard thin film deposition processes.
Solution Approach 2:
The storage layer is designed as a composite material system combining cobalt, iron, boron, and nitrogen elements in specific proportions. This composite structure, with boron concentration gradient within a cobalt-iron-boron-nitride matrix, achieves optimized magnetic properties and wettability while maintaining manufacturability through established sputtering or molecular beam epitaxy techniques.
3Stability of the object's composition
If the storage layer structure is optimized with varying boron concentrations, then thermal stability is improved, but device structure complexity increases
Solution Approach 1:
The storage layer is segmented into regions with different boron concentrations along the thickness direction. The first region near the base layer interface has one boron concentration range, while the second region near the reference layer interface has another range, creating a gradient structure. This segmentation enables independent optimization of different functional requirements: high boron concentration for wettability and low concentration for magnetic stability.
Solution Approach 2:
Different regions of the storage layer are given different local compositions to satisfy different functional requirements. The interface regions with the base layer and reference layer have optimized boron concentrations for wettability and magnetic coupling, respectively. This local quality optimization achieves enhanced thermal stability of magnetization without requiring complex overall device architecture.
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 proposed solution effectively decreases the write current required for magnetization switching, enhancing the power efficiency and nonvolatile performance of STT-MRAMs by stabilizing the magnetization and reducing the Gilbert damping constant, leading to lower power consumption and improved thermal stability.
Implementation Method 1
Spin transfer torque magnetic random access memories (STT-MRAMs) serving as nonvolatile memories that do not lose information when used in high-speed reading and writing
Implementation Method 2
optimizing the boron concentration and layer thickness to minimize spin pumping effects and improve wettability, thereby reducing the Gilbert damping constant
Implementation Method 3
Magnetoresistive element and magnetic memory
Data Source
AI summary
A magnetoresistive element according to an embodiment includes: a first layer containing nitrogen; a reference layer opposed to the first layer, the reference layer having a magnetization perpendicular to a face thereof opposed to the first layer, the magnetization of the reference layer being fixed; a storage layer disposed between the first layer and the reference layer, the storage layer having a magnetization perpendicular to a face thereof opposed to the first layer, the magnetization of the storage layer being changeable, and the storage layer including a second layer containing boron, and a third layer disposed between the second layer and the reference layer and containing boron, a boron concentration of the third layer being lower than a boron concentration of the second layer; and an intermediate layer disposed between the third layer and the reference.