Magnetic Tunnel Junctions with Boron-Absorbing Sidewalls
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Solution Overview
Problem
Boron in magnetic tunnel junctions reduces tunneling magnetoresistance (TMR), which is undesirable in magnetic tunnel junctions used for memory and logic circuitry.
Innovation Solution
Forming a magnetic tunnel junction with a B-absorbing material over the sidewalls of crystallized CoFe and MgO layers, where B is absorbed and reacted to form conductive or semiconductive products, thereby removing B from the electrode materials and maintaining the crystalline structure of CoFe and MgO, which helps in achieving higher TMR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If B is added to CoFe to assure amorphous deposition, then amorphous deposition is achieved, but TMR is reduced
Solution Approach 1:
The patent separates the B-containing CoFe layer into distinct regions: an amorphous CoFeB layer for stable deposition and a crystalline CoFe region for high TMR performance. This segmentation allows each region to fulfill its specific function without compromising the other.
Solution Approach 2:
The patent extracts B from the CoFe layer by forming a separate B-absorbing material layer (such as SiO2, Al2O3, or Ta) that selectively absorbs boron atoms. This removal of B from the CoFe crystalline regions restores the TMR property while maintaining amorphous deposition stability.
Solution Approach 3:
The patent introduces a B-absorbing material layer as an intermediary between the amorphous CoFeB deposition layer and the crystalline CoFe region. This intermediary layer captures excess B atoms, preventing them from degrading the TMR performance of the crystalline CoFe while allowing the amorphous layer to maintain its compositional stability.
2Reliability
If MgO tunnel insulator is used, then ideal tunneling properties are achieved, but B diffusion into MgO degrades performance
Solution Approach 1:
The patent introduces a B-absorbing material layer as a protective intermediary between the B-containing CoFeB layer and the MgO tunnel insulator. This intermediary layer captures B atoms through diffusion or absorption, preventing them from migrating into the MgO and degrading its tunneling properties.
Solution Approach 2:
The patent extracts B atoms from the system by providing a B-absorbing material that selectively takes up boron atoms through diffusion or chemical reaction. This extraction prevents B from entering the MgO tunnel insulator and maintains the integrity of the tunneling barrier.
3Stability of the object's composition
If annealing is performed to crystallize CoFe, then crystalline structure is achieved, but B remains in the matrix reducing TMR
Solution Approach 1:
The patent extracts B from the crystalline CoFe matrix by introducing a B-absorbing material layer that selectively absorbs boron atoms during or after the annealing process. This extraction allows the CoFe to maintain its crystalline structure while removing the harmful B that would otherwise reduce TMR.
Solution Approach 2:
The patent segments the CoFe structure into B-free crystalline CoFe regions for high TMR performance and separate B-containing regions that are either amorphous or have B extracted to adjacent absorbing material layers. This segmentation allows crystallization without B contamination in the functional regions.
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 method enhances the tunneling magnetoresistance of magnetic tunnel junctions by removing B from the electrode materials, improving their performance in memory and logic applications.
Implementation Method 1
B is absorbed and reacted to form conductive or semiconductive products, thereby removing B from the electrode materials
Implementation Method 2
B is absorbed and reacted to form conductive or semiconductive products
Implementation Method 3
The insulator material is sufficiently thin such that electrons can tunnel from one magnetic electrode to the other through the insulator material under appropriate conditions
Implementation Method 4
By passing a current through certain magnetic material (sometimes also referred to as polarizer material), one can produce a spin-polarized current. If a spin-polarized current is directed into a magnetic material, spin angular momentum can be transferred to that material, thereby affecting its magnetization orientation.
Data Source
AI summary
A method used while forming a magnetic tunnel junction comprises forming non-magnetic tunnel insulator material over magnetic electrode material. The tunnel insulator material comprises MgO and the magnetic electrode material comprises Co and Fe. B is proximate opposing facing surfaces of the tunnel insulator material and the magnetic electrode material. B-absorbing material is formed over a sidewall of at least one of the magnetic electrode material and the tunnel insulator material. B is absorbed from proximate the opposing facing surfaces laterally into the B-absorbing material. Other embodiments are disclosed, including magnetic tunnel junctions independent of method of manufacture.