TMR Element Side Wall Insulation for Annealing Diffusion Control
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Solution Overview
Problem
During the high-temperature annealing process for manufacturing Tunnel Magnetoresistive Effect (TMR) elements, chemical elements from the magnetic tunnel junction unit can diffuse to the side walls, altering the composition and compromising the element's characteristics, such as the magnetoresistive ratio.
Innovation Solution
A TMR element design that includes a side wall portion with insulation material covering the side surfaces of the magnetic tunnel junction unit, containing chemical elements similar to those in the unit's layers, which reduces diffusion and maintains the composition's integrity during annealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high-temperature annealing is performed to improve film quality and crystallinity, then the film quality and crystallinity of the TMR element are improved, but chemical elements diffuse to the side wall portion, changing the composition and degrading the magnetoresistive characteristics
Solution Approach 1:
An insulation layer is introduced as an intermediary between the TMR element and the side wall portion. This insulation layer contains chemical elements that match those in the TMR element layers, creating entropy that suppresses diffusion of chemical elements from the TMR element to the side wall during high-temperature annealing, while allowing the annealing to proceed for improving film quality and crystallinity
Solution Approach 2:
The chemical element composition of the insulation layer is specifically designed to match the chemical elements in the TMR element layers. This parameter matching creates entropic effects that suppress diffusion, allowing high-temperature annealing to improve film quality and crystallinity without degrading the magnetic tunnel junction unit's composition
2Manufacturing precision
If high-temperature annealing is performed to improve film quality and crystallinity, then the film quality and crystallinity of the TMR element are improved, but the magnetoresistive ratio decreases due to composition change
Solution Approach 1:
The insulation layer acts as a mediator during high-temperature annealing, suppressing the diffusion of chemical elements from the magnetic tunnel junction unit to the side wall. This maintains the composition and magnetoresistive ratio while allowing the annealing process to improve film quality and crystallinity
Solution Approach 2:
By matching the chemical element composition of the insulation layer with that of the TMR element layers, the patent creates entropic suppression of diffusion. This allows high-temperature annealing to improve film quality and crystallinity without degrading the magnetoresistive ratio
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 suppresses the movement of chemical elements to the side walls, ensuring the TMR element maintains its predetermined characteristics, like a high magnetoresistive ratio, even after annealing.
Implementation Method 1
a part of chemical elements constituting a magnetic tunnel junction element unit of the TMR element, for example, may move by diffusion or the like to a side wall portion
Implementation Method 2
entropy related to the contained element in the covered layer and the first region is increased, compared to that when only a chemical element different from the chemical element constituting the covered layer is present in the first region. Thus, the chemical element constituting the layer covered with the first region does not easily diffuse thermodynamically toward the first region
Implementation Method 3
A technology called 'spin injection magnetization reversal' in which a spin transfer torque (STT) is applied to the magnetization free layer from electron spins by causing a spin-polarized current to flow through the magnetization free layer
Implementation Method 4
A manufacturing process for a semiconductor device called the STT-MRAM may include an annealing step under a high temperature atmosphere of, for example, 300 degrees Celsius or higher
Implementation Method 5
the TMR element that uses an insulation layer (tunnel barrier layer) as the non-magnetic spacer layer generally has high element resistance but can realize a high magnetoresistive (MR) ratio
Data Source
AI summary
A TMR element includes a magnetic tunnel junction element unit and a side wall portion that includes an insulation material and is disposed on a side surface of the magnetic tunnel junction element unit. The magnetic tunnel junction element unit includes a reference layer, a magnetization free layer, a tunnel barrier layer that is stacked in a stack direction between the reference layer and the magnetization free layer, and a cap layer is stacked on the side of the magnetization free layer opposite to the tunnel barrier layer side. The side wall portion includes a first region that includes the insulation material and covers a side surface of at least one of the reference layer, the tunnel barrier layer, the magnetization free layer, or the cap layer of the magnetic tunnel junction element unit.