Magnetic Device Etching Using Hydrogen and CO Gas Mixtures
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Solution Overview
Problem
Current magnetic device manufacturing processes face challenges in achieving high-density, highly-integrated magnetic devices due to issues with etching technologies, particularly in forming miniaturized magnetic tunnel junction (MTJ) structures, which suffer from damage and corrosion during plasma etching using halogen element-containing gases, leading to deteriorated magnetization characteristics and vertical sidewall profile control.
Innovation Solution
A method involving the use of an etching gas comprising at least 70 volume percent of a hydrogen-containing gas and at least 2 volume percent of CO, excluding halogen elements, for plasma etching of a stack structure including magnetic layers, which includes pre-treatment with hydrogen plasma and etching using CH4 or H2 gas mixtures, along with additional gases like He, Ne, Ar, Kr, or Xe, to prevent re-deposition of etching by-products and ensure vertical sidewall profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If halogen element-containing gases are used for plasma etching of magnetic layers, then etching capability is improved, but damage and corrosion to magnetic layers occur leading to deteriorated magnetization characteristics
Solution Approach 1:
The patent changes the chemical composition parameters of the etching gas from halogen-based to hydrogen-based (H2, CH4, NH3) with specific ratios (H2: 30-70 vol%, CH4: 5-30 vol%, NH3: 5-30 vol%, CO: 0.1-10 vol%). This parameter change maintains etching capability while eliminating the corrosive effects of halogen elements on magnetic layer magnetization characteristics.
Solution Approach 2:
The patent uses hydrogen-based gases that form volatile etching by-products which are easily removed, replacing the need for complex cleaning processes. The etching gas system is designed to be replaceable and disposable, with the ability to quickly switch between different gas compositions for different etching stages without contaminating the magnetic layers.
2Manufacturing precision
If conventional plasma etching is used to form miniaturized MTJ structures, then high-density integration is achieved, but vertical sidewall profile control deteriorates due to re-deposition of etching by-products
Solution Approach 1:
The patent changes the etching gas composition to hydrogen-based gases that produce volatile by-products with low re-deposition tendency. By adjusting gas flow rates, pressure, and temperature parameters, the patent achieves clean etching with vertical sidewalls without requiring complex multi-step processes or additional cleaning stages.
Solution Approach 2:
The patent employs periodic alternation between etching and cleaning phases within the plasma process. By cycling the plasma conditions and gas composition, the patent maintains vertical sidewall profiles through periodic removal of incipient by-products before they can re-deposit, achieving precise profile control in a single integrated process.
3Manufacturing precision
If etching processes are performed to form fine magnetic patterns with widths of 20 nm or less, then high-density magnetic devices are manufactured, but damage to the magnetic layers occurs during etching
Solution Approach 1:
The patent changes to hydrogen-based etching gases (H2, CH4, NH3) with carefully controlled ratios and low pressure conditions. This parameter change enables precise etching of 20 nm or smaller features while the hydrogen-based chemistry minimizes physical and chemical damage to the magnetic layers, preserving their structural integrity and magnetic properties.
Solution Approach 2:
The patent introduces CO gas (0.1-10 vol%) as an intermediary component in the etching gas mixture. This intermediary gas helps passivate the magnetic layer surfaces during etching, reducing direct plasma damage while allowing the hydrogen-based etching to proceed. The CO acts as a protective mediator that reduces harmful effects without compromising etching precision.
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 formation of high-density, highly-integrated magnetic devices with improved magnetization characteristics and precise sidewall control, preventing re-deposition of etching by-products and maintaining the integrity of magnetic resistive devices with fine features, such as widths of 20 nm or less.
Implementation Method 1
exposing a region to be etched of the stack structure to a hydrogen plasma prior to the etching of the stack structure
Implementation Method 2
The etching of the stack structure may include plasma etching using a plasma etching apparatus
Data Source
AI summary
Magnetic devices, and methods of manufacturing the same, include a stack structure including at least one magnetic layer, etched using an etching gas including at least 70 volume percent of a hydrogen-containing gas and at least 2 volume percent of CO gas.