Spin-Orbit Torque MRAM Barrier Layer Segmentation
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Solution Overview
Problem
The etching process in spin-orbit torque MRAM fabrication often damages the bottom ultra-thin heavy metal layer, leading to uneven operation characteristics and component failure due to lack of uniformity in the metal layer structure.
Innovation Solution
A spin-orbit torque MRAM structure with a uniform ultra-thin heavy metal layer is achieved by using a barrier layer with varying thickness areas to protect the bottom metal layer during etching, allowing for precise control of etching processes through selectivity ratios between materials, ensuring the magnetic tunnel junction's integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a standard etching process is used to fabricate top pinned layer MTJ structure, then the etching process can terminate at the barrier layer or free magnetic layer, but the bottom ultra-thin heavy metal layer becomes damaged resulting in uneven operation characteristics and component failure
Solution Approach 1:
The patent divides the continuous barrier layer into two distinct thickness regions: a first area with a first thickness and a second area with a second thickness. This segmentation allows the etching process to interact differently with each region, enabling precise control over etching termination while protecting the bottom heavy metal layer through the thicker first area.
Solution Approach 2:
The barrier layer is designed with non-uniform thickness distribution, where the first area has a greater thickness than the second area. This local quality variation enables the thicker first area to protect the bottom heavy metal layer during etching, while the thinner second area allows controlled etching termination to achieve the desired MTJ structure.
2Reliability
If the bottom ultra-thin heavy metal layer is protected during etching, then component failure is prevented, but the etching process complexity increases
Solution Approach 1:
The barrier layer is pre-formed with a non-uniform thickness profile before the etching process begins. The first area is intentionally made thicker than the second area in advance, so that during subsequent etching, the thicker first area automatically provides protection to the bottom heavy metal layer without requiring additional protective measures or process steps.
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 enhances the production yield of spin-orbit torque MRAM by maintaining the integrity of the ultra-thin metal layers, enabling consistent operation and preventing component failure, while also optimizing the spin Hall effect and magnetic moment reversal.
Implementation Method 1
The highest efficiency of the spin Hall effect can be achieved in a 3-nm ultra-thin heavy metal layer
Implementation Method 2
The pinned layer is etched using the patterned photoresist layer as a mask to expose the second area of the barrier layer
Data Source
AI summary
A spin-orbit torque MRAM is provided. The spin-orbit torque MRAM includes a spin Hall metal layer, a free magnetic layer disposed on the spin Hall metal layer, a barrier layer, and a pinned layer. The free magnetic layer includes a first area and a second area located on both sides thereof. The barrier layer includes a first area and a second area located on both sides thereof. The first area of the barrier layer is disposed on that of the free magnetic layer, and the second area of the barrier layer is disposed on that of the free magnetic layer. The pinned layer is disposed on the first area of the barrier layer.