Magnetoresistive Stack Encapsulation via Multi-Layer Oxidation
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Solution Overview
Problem
Magnetoresistive devices, particularly those with magnetic tunnel junctions (MTJs), face issues with contamination and excessive oxidation, which affect their reliability and thermal endurance during manufacturing and operation.
Innovation Solution
A method involving the deposition of multiple encapsulation layers with varying conductivity and oxidation/nitridation levels is employed to protect MTJs, including a conductive first layer, an insulative second layer, and a conductive or insulative third layer, which are formed through processes like sputter etching and oxidation/nitridation, to prevent contamination and oxidation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single encapsulation layer is used to protect MTJ, then the structure is simple, but the protection against contamination and oxidation is insufficient
Solution Approach 1:
The encapsulation structure is divided into multiple layers (first encapsulation layer, second encapsulation layer, and third encapsulation layer) with different materials and properties. Each layer provides specific protection functions, creating a multi-barrier system that effectively prevents contamination and oxidation while maintaining manageable complexity through functional segmentation.
Solution Approach 2:
The patent employs composite encapsulation layers made of different materials (e.g., aluminum, aluminum oxide, titanium nitride, tungsten) with varying conductivity and oxidation resistance. This composite approach combines the advantages of each material to achieve superior overall protection against contamination and oxidation that cannot be attained with a single material.
2Reliability
If multiple encapsulation layers are deposited to improve protection, then reliability improves, but manufacturing process complexity increases
Solution Approach 1:
The first encapsulation layer is deposited and partially oxidized before subsequent processing steps. This preliminary encapsulation provides immediate protection to the MTJ structure during subsequent etching and processing, preventing contamination from the outset rather than requiring complete protection throughout the entire process.
Solution Approach 2:
The patent controls the oxidation state of encapsulation layers by adjusting oxidation parameters (time, temperature, oxygen flow). By precisely controlling these parameters, the encapsulation layers achieve optimal protection properties without requiring excessive processing steps, balancing reliability improvement with manufacturing simplicity.
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 reliability and thermal endurance of MTJ stacks by reducing unwanted contamination and oxidation, improving the overall performance and longevity of magnetoresistive devices.
Implementation Method 1
The plurality of encapsulation layers may include conductor materials (for example, metals or metal alloys), semi-conductor materials and/or insulator materials. In one embodiment, the encapsulation layers may be deposited as a conductor (for example, a metal) and thereafter at least partially transformed to an insulator (for example, via oxidation or nitridation).
Implementation Method 2
The plurality of encapsulation layers may include conductor materials (for example, metals or metal alloys), semi-conductor materials and/or insulator materials. In one embodiment, the encapsulation layers may be deposited as a conductor (for example, a metal) and thereafter at least partially transformed to an insulator (for example, via oxidation or nitridation).
Implementation Method 3
A first encapsulation layer is deposited on a partially formed magnetoresistive stack/structure and thereafter physical etching (for example, sputter etching, ion etching or milling, and/or ion-beam etching or milling) to remove re-deposited material
Data Source
AI summary
A method of manufacturing a magnetoresistive stack/structure comprising etching through a second magnetic region to (i) provide sidewalls of the second magnetic region and (ii) expose a surface of a dielectric layer; depositing a first encapsulation layer on the sidewalls of the second magnetic region and over the dielectric layer; etching the first encapsulation layer which is disposed over the exposed surface of the dielectric layer. The method further includes (a) depositing a second encapsulation layer: (i) on the first encapsulation layer disposed on the sidewalls of the second magnetic region and (ii) over the exposed surface of the dielectric layer and (b) depositing a third encapsulation layer: (i) on the second encapsulation layer which is on the first encapsulation layer and the exposed surface of the dielectric layer. The method also includes etching the remaining layers of the stack/structure (via one or more etch processes).