Magnetoresistive Memory Etching via Segmented Ion and Reactive Processes
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Solution Overview
Problem
Existing methods for manufacturing magnetoresistive memory devices face challenges in forming high-density memory cells with MTJ elements that have both high aspect ratios and good magnetic properties, as ion beam etching can lead to redeposition and magnetic property deterioration, while reactive ion etching can further degrade magnetic properties.
Innovation Solution
A method involving sequential etching processes, where ion beam etching is used to form the ferromagnets and nonmagnets with minimal damage, followed by reactive ion etching to process the conductors and switching elements, allowing for the formation of MTJ elements with better performance and high-density memory cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If ion beam etching is used to form MTJ elements, then high aspect ratios can be achieved, but magnetic properties deteriorate due to redeposition
Solution Approach 1:
The patent divides the etching process into two separate segments: ion beam etching for forming the MTJ elements (achieving high aspect ratios) and reactive ion etching for forming conductors and switching elements. This segmentation allows each etching method to be optimized for its specific purpose, preventing magnetic property deterioration in the MTJ elements while still achieving the desired high aspect ratios.
2Manufacturing precision
If reactive ion etching is used to form conductors and switching elements, then manufacturing precision is improved, but magnetic properties of nearby ferromagnets are degraded
Solution Approach 1:
The patent applies different etching methods to different regions of the device structure. Ion beam etching is used locally for the MTJ elements where magnetic properties must be preserved, while reactive ion etching is used locally for conductors and switching elements where high precision is needed but magnetic property degradation is not a concern. This local quality approach ensures that each region receives the appropriate processing method.
3Productivity
If high-density memory cells are formed, then productivity is improved, but magnetic properties deteriorate due to increased redeposition
Solution Approach 1:
By segmenting the etching process into two distinct steps with different methods, the patent enables high-density memory cell formation without the magnetic property deterioration that would result from using ion beam etching alone for all structures. The reactive ion etching step can be applied to surrounding structures without affecting the MTJ element magnetic properties, allowing for higher overall device density.
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 magnetoresistive memory devices with MTJ elements that maintain good magnetic properties and high aspect ratios, overcoming the limitations of previous etching techniques.
Implementation Method 1
The second layer stack is etched with an ion beam that travels through the opening
Implementation Method 2
The first layer stack is etched by reactive ion etching through the opening
Implementation Method 3
a magnetoresistive effect is used to store data
Data Source
AI summary
According to one embodiment, a method for manufacturing a magnetoresistive memory device includes forming a first layer stack on a substrate. A second layer stack including a first ferromagnet is formed on the first layer stack. A mask including a first portion and an opening is formed above the second layer stack. The second layer stack is etched with an ion beam that travels through the opening. The first layer stack is etched by reactive ion etching through the opening.