Ferromagnetic Tunnel Junction Side Surface Oxidation
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Solution Overview
Problem
The existing methods for manufacturing ferromagnetic tunnel junction elements face challenges in maintaining high fabrication yield while avoiding changes in magnetic characteristics and minimizing the area occupied by the elements, as direct oxidation of side surfaces can alter magnetic properties and the use of protective films with multiple layers increases production costs and reduces storage capacity.
Innovation Solution
A ferromagnetic tunnel junction element is developed with a first magnetic layer, a first insulating layer, and a second magnetic layer containing a magnetic transition metal, where a magnesium oxide film is formed by oxidizing a metallic magnesium film on the side surfaces of the second magnetic layer to cover and insulate them, preventing short-circuiting and maintaining magnetic characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If direct oxidation of side surfaces is performed to remove residues and prevent short-circuiting, then fabrication yield is improved, but magnetic characteristics change
Solution Approach 1:
A magnesium oxide film is introduced as an intermediary substance between the oxidation process and the magnetic layers. The magnesium oxide film is formed on the side surfaces first, then oxidation is performed in a nitrogen atmosphere. This intermediary layer prevents direct oxidation of the magnetic layers while still allowing the oxidation process to remove residues, thus resolving the contradiction between preventing short-circuiting and maintaining magnetic characteristics
Solution Approach 2:
The patent changes the atmospheric parameters by performing oxidation in a nitrogen atmosphere instead of air or oxygen atmosphere. This parameter change allows oxidation to proceed sufficiently to remove residues and prevent short-circuiting, while the nitrogen atmosphere limits excessive oxidation that would alter magnetic characteristics. The controlled atmospheric composition resolves the contradiction between these two requirements
2Reliability
If a protective film with two-layer structure is formed to prevent short-circuiting, then fabrication yield is improved, but device area increases and production cost increases
Solution Approach 1:
The patent extracts and eliminates the need for a complex two-layer protective film structure. Instead, it uses a simplified single-layer magnesium oxide film combined with controlled oxidation in nitrogen atmosphere. This extraction of unnecessary complexity reduces production cost and device area while still achieving the goal of preventing short-circuiting through effective residue removal
Solution Approach 2:
The magnesium oxide film serves multiple functions simultaneously: it acts as a protective barrier during processing, provides a substrate for controlled oxidation, and ultimately forms part of the insulating structure. This multi-functionality eliminates the need for separate protective layers, reducing device complexity and production cost while maintaining high fabrication yield
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 maintains high fabrication yield, prevents changes in magnetic characteristics, and avoids increased area occupation and production costs, effectively addressing the limitations of previous methods.
Implementation Method 1
a magnesium oxide film is formed by oxidizing a metallic magnesium film on the side surfaces of the second magnetic layer
Data Source
AI summary
The present disclosure is to provide a ferromagnetic tunnel junction element and a method of manufacturing the ferromagnetic tunnel junction element capable of avoiding changes in the characteristics of the element and maintaining a high fabrication yield, while avoiding an increase in the area occupied by the element and an increase in the number of manufacturing steps. The ferromagnetic tunnel junction element to be provided includes: a first magnetic layer; a first insulating layer disposed on the first magnetic layer; a second magnetic layer containing a magnetic transition metal, the second magnetic layer being disposed on the first insulating layer; and a magnesium oxide film containing the magnetic transition metal, the magnesium oxide film being disposed to cover the side surfaces of the second magnetic layer.