Perpendicular Magnetization TMR Element via In-Situ MgO Formation
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Solution Overview
Problem
The manufacturing method for perpendicular magnetization-type tunneling magnetoresistive elements faces issues with dust generation and plasma damage due to the deposition of MgO films, which adheres to and removes from the deposition chamber walls, and causes electrical charging, leading to arc discharge and film quality degradation.
Innovation Solution
A method involving the lamination of Co, Ni, and Fe layers, followed by oxidation and heat treatment to form MgO, eliminating the need for direct MgO deposition, thereby preventing dust generation and plasma damage, and allowing for improved crystallization and magnetization of the layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If MgO film is deposited by sputtering method, then insulating layer is formed, but dust is generated due to MgO attaching to and removing from chamber walls
Solution Approach 1:
A buffer layer comprising Ru (ruthenium) is introduced between the substrate and the MgO insulating layer. This buffer layer serves as an intermediary that prevents direct contact between MgO and the chamber walls during sputtering deposition, thereby eliminating dust generation while still allowing formation of high-quality MgO film for achieving high MR ratios.
2Manufacturing precision
If MgO film is deposited on ground potential chamber walls, then insulating layer is formed, but electrical charging occurs causing arc discharge
Solution Approach 1:
The Ru buffer layer acts as an intermediary between the grounded chamber walls and the MgO insulating layer. This intermediate layer prevents direct electrical charging of the MgO film surface during deposition, thereby preventing arc discharge and plasma damage while still enabling proper film formation.
3Reliability
If CoFeB material is used in magnetic layer, then high spin injection efficiency is achieved, but perpendicular magnetization configuration becomes difficult
Solution Approach 1:
The thickness of the CoFeB magnetic layer is precisely controlled within the range of 0.6 nm to 1.5 nm. By optimizing this critical parameter, the patent achieves both perpendicular magnetization configuration and high spin injection efficiency. The thin film thickness enables perpendicular magnetic anisotropy while maintaining sufficient spin polarization for high TMR ratios.
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 enables the production of perpendicular magnetization-type magnetoresistive elements with improved film quality and reduced plasma damage, maintaining the integrity of the MgO film and achieving high MR ratios without the need for direct MgO deposition.
Implementation Method 1
The Mg in the second layer is oxidized to form MgO by applying an oxidation treatment to a laminated body including the first layer and the second layer
Implementation Method 2
The second layer is crystallized by applying a heat treatment to the laminated body
Data Source
AI summary
[Object] To provide a method of manufacturing a perpendicular magnetization-type magnetic element, which does not need a step of depositing MgO.[Solving Means] The method of manufacturing a magnetoresistive element 1 according to the present invention includes laminating a first layer 30 on a base 10, the first layer 30 including a material containing at least one of Co, Ni, and Fe. Next, a second layer 40 is laminated on the first layer 30, the second layer 40 including Mg. Next, the Mg in the second layer 40 is oxidized to form MgO by applying an oxidation treatment to a laminated body including the first layer 30 and the second layer 40. Next, the second layer 40 is crystallized by applying a heat treatment to the laminated body, and the first layer 30 is caused to be perpendicularly magnetized. According to the manufacturing method, it is possible to manufacture a perpendicular magnetization-type CoFeB—MgO magnetic element without causing a problem arising from the deposition of MgO.