Tri-Layer Magnetic Spacer for Strong RL-PL Exchange Coupling
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Solution Overview
Problem
Conventional magnetic memory devices, such as MRAM, face challenges in robustness against BEOL processing due to mismatched crystal structures and textures between the magnetic pinned layer and the MTJ stack, leading to weak magnetic coupling and limited downscaling capabilities.
Innovation Solution
A magnetic tri-layer spacer is introduced between the magnetic reference and pinned layers, comprising a first texture breaking layer, a magnetic bridge layer, and a second texture breaking layer, which provides strong direct exchange interaction and disrupts textures, enabling robust magnetic coupling while minimizing the magnetic structure's height.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional magnetic structure is used without a tri-layer spacer, then the structure is simpler and shorter, but the magnetic coupling between RL and PL/HL is weak and the texture mismatch causes poor BEOL processing robustness
Solution Approach 1:
The spacer is divided into three distinct functional layers: a first texture breaking layer (e.g., Ru, Ir, or Cr) to disrupt unwanted crystallographic alignment, a magnetic bridge layer (e.g., Co, Ni, Fe, or their alloys) to provide strong direct exchange coupling, and a second texture breaking layer to complete the texture disruption. This segmentation allows each layer to perform its specific function optimally, achieving both strong magnetic coupling and texture breaking without excessive overall complexity
Solution Approach 2:
The magnetic bridge layer acts as an intermediary between the RL and PL/HL, enabling strong direct exchange interaction while the texture breaking layers mediate the crystallographic mismatch. This intermediary structure allows the magnetic coupling to occur through the spacer while preventing unwanted texture propagation, thereby improving BEOL processing robustness without requiring direct contact between RL and PL/HL
2Reliability
If the spacer is made thicker to improve texture breaking, then texture disruption is enhanced, but the magnetic structure height increases and magnetic coupling strength may be reduced
Solution Approach 1:
Different regions of the spacer have different thicknesses optimized for their specific functions: the texture breaking layers are kept thin (e.g., 0.3-1.0 nm) to provide sufficient texture disruption while minimizing height increase, the magnetic bridge layer has optimal thickness (e.g., 0.5-2.0 nm) for strong exchange coupling, and the overall spacer thickness is controlled to balance texture breaking effectiveness with magnetic structure height constraints for high-density applications
3Reliability
If strong magnetic coupling is achieved through direct exchange interaction, then the pinning field is enhanced, but the structure becomes more sensitive to manufacturing variations
Solution Approach 1:
The spacer uses a composite structure combining different material types: transition metal layers (Ru, Ir, Cr) for texture breaking, ferromagnetic bridge layers (Co, Ni, Fe or alloys) for magnetic coupling, and potentially antiferromagnetic layers. This composite approach allows each material to contribute its optimal properties, providing robust magnetic coupling that is less sensitive to individual layer thickness variations compared to homogeneous structures
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 enhances the pinning field of the magnetic reference layer, improves BEOL process tolerance, and enables high-density applications by achieving strong magnetic coupling without losing perpendicular magnetic anisotropy, thus overcoming the limitations of conventional designs.
Implementation Method 1
the magnetic RL and the magnetic PL or HL are magnetically coupled across the spacer through direct exchange interaction
Data Source
AI summary
The disclosed technology relates generally to the field of magnetic devices, in particular to magnetic memory devices or logic devices. The disclosed technology presents a magnetic structure for a magnetic device, wherein the magnetic structure comprises a magnetic reference layer (RL); a spacer provided on the magnetic RL, the spacer comprising a first texture breaking layer provided on the magnetic RL, a magnetic bridge layer provided on the first texture breaking layer, and a second texture breaking layer provided on the magnetic bridge layer. Further, the magnetic structure comprising a magnetic pinned layer (PL) or hard layer (HL) provided on the spacer, wherein the magnetic RL and the magnetic PL or HL are magnetically coupled across the spacer through direct exchange interaction.