Reducing Switching Energy in Perpendicular MTJs with SEL
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Summary
Problems
Magnetic random access memory (MRAM) with perpendicular anisotropy faces challenges in reducing the threshold voltage and current required for switching the free layer magnetization, which limits its practical applications, as existing solutions have primarily focused on in-plane MTJ designs rather than perpendicular ones.
Innovation solutions
A spin transfer torque magnetic random access memory (STTMRAM) element with a perpendicular magnetic orientation, incorporating a seed layer, a magnetic tunnel junction (MTJ) with a pinned layer and a free layer, and a switching-enhancing layer (SEL) with in-plane magnetic orientation, which generates magneto-static fields to tilt the outer edges of the free layer's magnetic moments, facilitating easier switching with minimal impact on thermal stability.
TRIZ Analysis
Specific contradictions:
General conflict description:
Principle concept:
If perpendicular magnetic anisotropy is used in MTJ to improve density and thermal stability, then storage capacity and reliability are improved, but the effective coercivity field becomes non-uniform and high, making switching difficult
Why choose this principle:
The patent applies local quality by creating different magnetic environments within the free layer. The outer edges of the free layer experience enhanced in-plane magnetic anisotropy due to the adjacent SEL, while the center maintains perpendicular anisotropy. This spatial variation in magnetic properties allows easier switching at the edges without compromising the thermal stability provided by perpendicular anisotropy in the center.
Principle concept:
If perpendicular magnetic anisotropy is used in MTJ to improve density and thermal stability, then storage capacity and reliability are improved, but the effective coercivity field becomes non-uniform and high, making switching difficult
Why choose this principle:
The patent segments the switching process by distinguishing between edge regions and center regions of the free layer. The SEL specifically targets the outer edges to provide switching assistance, while the center region maintains its perpendicular magnetic anisotropy for stability. This segmentation allows different parts of the free layer to have optimized properties for their respective functions.
Application Domain
Data Source
AI summary:
A spin transfer torque magnetic random access memory (STTMRAM) element with a perpendicular magnetic orientation, incorporating a seed layer, a magnetic tunnel junction (MTJ) with a pinned layer and a free layer, and a switching-enhancing layer (SEL) with in-plane magnetic orientation, which generates magneto-static fields to tilt the outer edges of the free layer's magnetic moments, facilitating easier switching with minimal impact on thermal stability.
Abstract
A STTMRAM element includes a magnetic tunnel junction (MTJ) having a perpendicular magnetic orientation. The MTJ includes a barrier layer, a free layer formed on top of the barrier layer and having a magnetic orientation that is perpendicular and switchable relative to the magnetic orientation of the fixed layer. The magnetic orientation of the free layer switches when electrical current flows through the STTMRAM element. A switching-enhancing layer (SEL), separated from the free layer by a spacer layer, is formed on top of the free layer and has an in-plane magnetic orientation and generates magneto-static fields onto the free layer causing the magnetic moments of the outer edges of the free layer to tilt with an in-plane component while minimally disturbing the magnetic moment at the center of the free layer to ease the switching of the free layer and to reduce the threshold voltage/current.