Magnetic Cell Core with Getter Material for STT-MRAM
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Solution Overview
Problem
The challenge in designing STT-MRAM cells is to enhance magnetic anisotropy strength without increasing electrical resistance, which degrades magnetoresistance and requires higher programming voltage.
Innovation Solution
Incorporating a getter material proximate to a secondary oxide region to reduce its oxygen concentration, thereby decreasing electrical resistance while maintaining high magnetic anisotropy strength, achieved by forming a magnetic cell core with a free region between two oxide regions, one functioning as a tunnel barrier and the other with a getter material to remove oxygen, thus lowering the overall resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a secondary oxide region is added to enhance magnetic anisotropy strength, then magnetic anisotropy strength is improved, but electrical resistance increases
Solution Approach 1:
The patent extracts oxygen from the secondary oxide region by introducing a getter material (such as titanium, tantalum, or tungsten) that has a higher affinity for oxygen. This oxygen removal process converts the high-resistance secondary oxide region into a lower-resistance region while preserving its magnetic anisotropy-inducing properties, thereby resolving the contradiction between enhancing magnetic anisotropy and minimizing electrical resistance
Solution Approach 2:
The patent changes the oxygen concentration parameter in the secondary oxide region by controlling the getter material's oxygen absorption during fabrication. By adjusting the oxygen concentration from high to low, the electrical resistance is reduced while maintaining the magnetic anisotropy strength provided by the oxide region's presence
2Strength
If oxygen concentration in secondary oxide region is high, then magnetic anisotropy strength is maintained, but electrical resistance increases
Solution Approach 1:
The getter material selectively extracts excess oxygen from the secondary oxide region, reducing oxygen concentration to optimize both magnetic anisotropy and electrical resistance. This extraction process improves magnetoresistance by lowering resistance while preserving the magnetic anisotropy function
3Strength
If secondary oxide region with high oxygen concentration is used, then magnetic anisotropy is enhanced, but programming voltage increases
Solution Approach 1:
By removing oxygen from the secondary oxide region using the getter material, the electrical resistance is reduced. This resistance reduction directly lowers the programming voltage required to switch the magnetic state, while the oxide region continues to provide the necessary magnetic anisotropy enhancement
Solution Approach 2:
The patent optimizes the oxygen concentration parameter in the secondary oxide region to achieve a balance where magnetic anisotropy is sufficiently enhanced but electrical resistance (and thus programming voltage) is minimized. The getter material enables precise control of this parameter
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 results in higher magnetoresistance, lower RA product, and reduced programming voltage, maintaining high magnetic anisotropy strength without degrading other properties.
Implementation Method 1
Incorporating a getter material proximate to a secondary oxide region to reduce its oxygen concentration, thereby decreasing electrical resistance
Implementation Method 2
Magnetic Random Access Memory (MRAM) is a non-volatile computer memory technology based on magnetoresistance
Implementation Method 3
The spin-polarized electron current exerts the torque on the free region. When the torque of the spin-polarized electron current passing through the core is greater than a critical switching current density (Jc) of the free region, the direction of the magnetic orientation of the free region is switched
Data Source
AI summary
A magnetic cell includes a free region between an intermediate oxide region (e.g., a tunnel barrier) and a secondary oxide region. Both oxide regions may be configured to induce magnetic anisotropy (“MA”) with the free region, enhancing the MA strength of the free region. A getter material proximate to the secondary oxide region is formulated and configured to remove oxygen from the secondary oxide region, reducing an oxygen concentration and an electrical resistance of the secondary oxide region. Thus, the secondary oxide region contributes only minimally to the electrical resistance of the cell core. Embodiments of the present disclosure therefore enable a high effective magnetoresistance, low resistance area product, and low programming voltage along with the enhanced MA strength. Methods of fabrication, memory arrays, memory systems, and electronic systems are also disclosed.