Magneto resistive element
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Solution Overview
Problem
The existing magneto resistive elements using Heusler alloys face challenges in achieving high crystallinity without requiring high-temperature film formation or thick base substrates, which affects the magnetoresistance ratio (MR ratio) of magnetic sensors.
Innovation Solution
Incorporating a buffer layer with specific atomic compositions, such as Fe, Si, and Ru, that are amorphous after film formation, to facilitate the crystallization of Heusler alloys in the first ferromagnetic layer at lower annealing temperatures, thereby enhancing the MR ratio without the need for high-temperature processing or thick substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high-temperature film formation is used to crystallize Heusler alloy, then crystallinity of ferromagnetic layer is improved, but manufacturing complexity and cost increase
Solution Approach 1:
An amorphous buffer layer is introduced as an intermediary between the substrate and the Heusler alloy ferromagnetic layer. This buffer layer facilitates crystallization of the Heusler alloy at lower annealing temperatures (200-400°C) by providing a suitable nucleation interface, thereby avoiding the need for high-temperature film formation processes while still achieving high crystallinity in the ferromagnetic layer.
Solution Approach 2:
The invention changes the temperature parameter of the film formation process from high temperature to low temperature annealing (200-400°C). By combining low-temperature deposition with a specific amorphous buffer layer composition, the process achieves crystallization without requiring high-temperature processing, thus reducing manufacturing complexity and cost.
2Manufacturing precision
If thick base substrate with predetermined crystallinity is used, then crystallinity of ferromagnetic layer is improved, but device complexity and cost increase
Solution Approach 1:
The amorphous buffer layer serves as a mediator that decouples the crystallinity requirement from the substrate. Instead of requiring a thick crystalline substrate, the buffer layer provides the necessary crystallization interface, allowing the use of simpler, thinner substrates while still achieving high crystallinity in the Heusler alloy layer.
Solution Approach 2:
The invention extracts the crystallization function from the substrate and transfers it to the amorphous buffer layer. This separation allows the substrate to be simpler and thinner, while the buffer layer specifically provides the crystallization interface needed for the Heusler alloy, thereby reducing substrate requirements and device complexity.
3Temperature
If amorphous buffer layer with specific composition is used, then crystallization temperature is reduced, but buffer layer composition control becomes more critical
Solution Approach 1:
The invention changes the composition parameters of the buffer layer to achieve amorphous structure with specific atomic ratios. By carefully controlling the buffer layer composition (e.g., using elements with appropriate atomic radii ratios and avoiding certain element combinations), the process enables low-temperature annealing (200-400°C) while maintaining manufacturability through standardized deposition techniques.
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 configuration allows for the easy crystallization of Heusler alloys, resulting in a higher MR ratio and improved performance of magnetic sensors, while reducing manufacturing complexities and costs.
Implementation Method 1
facilitate the crystallization of Heusler alloys in the first ferromagnetic layer at lower annealing temperatures
Implementation Method 2
The buffer layer contains at least a first atom, a second atom, and a third atom other than Co as main components
Data Source
AI summary
A magneto resistive element includes a first ferromagnetic layer, a second ferromagnetic layer, a nonmagnetic layer, and a buffer layer. The nonmagnetic layer is between the first ferromagnetic layer and second ferromagnetic layer. The buffer layer is in contact with the first ferromagnetic layer. The first ferromagnetic layer contains a Heusler alloy containing Co. The buffer layer contains at least a first atom, a second atom, and a third atom other than Co as main components. The buffer layer does not contain Co or contains Co at a proportion less than a compositional proportion of the first atom, the second atom, and the third atom. In a case where an atomic radius of any one atom of the first atom, the second atom, and the third atom is taken as a reference, an atomic radius of another atom thereof is 95% or less or 105% or more of the reference.