Magnetic Tunnel Junction Layer Stack for Diffusion-Resistant TMR
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Solution Overview
Problem
Existing magnetic tunnel junction elements face issues of exchange field degradation and reduced tunneling magnetoresistance due to diffusion and crystalline collisions among layers, which affect their performance and operation speed.
Innovation Solution
Incorporating an amorphous buffer layer and a BCC structured auxiliary layer between the ferromagnetic layers to prevent diffusion and crystalline collisions, while maintaining crystallinity, thereby enhancing the exchange field and tunneling magnetoresistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If layers are directly stacked to form magnetic tunnel junction element, then device structure is simple, but diffusion and crystalline collisions occur causing exchange field degradation and reduced tunneling magnetoresistance
Solution Approach 1:
An amorphous buffer layer is introduced as an intermediary between the lower ferromagnetic layer and upper layers. This buffer layer prevents direct crystalline contact and diffusion between adjacent ferromagnetic layers, thereby maintaining exchange field strength and tunneling magnetoresistance without requiring complex structural modifications
Solution Approach 2:
The patent employs a composite layered structure combining crystalline ferromagnetic layers with amorphous buffer layers. The amorphous phase acts as a diffusion barrier while the crystalline phases maintain magnetic properties, creating a composite structure that simultaneously achieves high tunneling magnetoresistance and prevents exchange field degradation
2Reliability
If amorphous buffer layer and BCC structured auxiliary layer are added to prevent diffusion, then tunneling magnetoresistance and exchange field are enhanced, but device structure becomes more complex
Solution Approach 1:
The magnetic tunnel junction structure is segmented into distinct functional layers: ferromagnetic layers for magnetism, amorphous buffer layers for diffusion prevention, and BCC auxiliary layers for crystalline structure control. This segmentation allows each layer to optimize its specific function while maintaining overall structural organization
Solution Approach 2:
Different layers are assigned different local qualities: crystalline structure in ferromagnetic layers for magnetic properties, amorphous structure in buffer layers for diffusion barrier function, and BCC structure in auxiliary layers for epitaxial growth control. Each local region is optimized for its specific purpose
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 solution effectively prevents diffusion and crystalline collisions, resulting in improved tunneling magnetoresistance and exchange field, thus enhancing the performance and operation speed of the magnetic tunnel junction elements.
Implementation Method 1
Incorporating an amorphous buffer layer and a BCC structured auxiliary layer between the ferromagnetic layers to prevent diffusion and crystalline collisions
Implementation Method 2
The resistance of a magnetic tunnel junction element changes based on the magnetization direction of a free layer. For example, if the magnetization direction of the free layer is the same as that of a pinned layer, the magnetic tunnel junction element has a low resistance
Data Source
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AI summary
A magnetic tunnel junction element including: a pinned layer (120) and a free layer (140) facing each other; a buffer layer (151) on the pinned layer (120); an auxiliary layer (152) on the buffer layer (151); a polarization enhancement layer (160) between the auxiliary layer (152) and the free layer (140); and a tunnel barrier layer between the polarization enhancement layer (160) and the free layer (140), wherein the buffer layer (151) is amorphous and includes CoFeBX, and X is W, Mo, Re or Ta, the auxiliary layer (152) includes W, Mo, or Ta.