SOT-MRAM Sidewall Protection Structure to Prevent SOT Etch Damage
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Solution Overview
Problem
The dry etching process used to form protection layers in spin-orbit torque magnetic random access memory (SOT-MRAM) damages the SOT layer, which needs to be protected.
Innovation Solution
A magnetic memory structure with a first and second protection layer on the sidewall of the MTJ stack, where the first protection layer is between the second protection layer and the MTJ stack, and a notch is created between the second protection layer and the SOT layer, utilizing a combination of dry and wet etching processes to form these layers without damaging the SOT layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a dry etching process is performed on the protection material layer to form the protection layer, then the protection layer can be formed on the sidewall of the MTJ stack, but the SOT layer will be damaged
Solution Approach 1:
The protection structure is divided into two separate protection layers: a first protection layer that contacts the MTJ stack sidewall and a second protection layer that provides additional protection. This segmentation allows the etching process to be better controlled and the SOT layer to be protected from damage while still forming the necessary protection structure.
Solution Approach 2:
The first protection layer is formed on the MTJ stack sidewall before the dry etching process is performed. This preliminary protective layer prevents the etching process from directly contacting and damaging the SOT layer, while still allowing the second protection layer to be formed for complete protection.
2Object-affected harmful factors
If a protection material layer is formed on the MTJ stack followed by dry etching, then sidewall protection is achieved, but damage to the SOT layer occurs
Solution Approach 1:
The first protection layer acts as an intermediary between the dry etching process and the SOT layer. It allows the etching process to proceed for forming the second protection layer while preventing direct contact between the etchant and the SOT layer, thus eliminating the harmful effect of etching damage while maintaining the protective function.
Solution Approach 2:
The protection structure is designed with different layers having different properties and positions: the first protection layer is localized at the MTJ stack sidewall for direct protection, while the second protection layer provides extended protection. This local quality differentiation allows precise control over where protection is provided and where etching can safely occur.
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 configuration prevents damage to the SOT layer during the dry etching process for forming the second protection layer, ensuring the integrity of the SOT layer while maintaining the functionality of the MTJ stack.
Implementation Method 1
a dry etching process is performed on the protection material layer to form the protection layer on the sidewall of the MTJ stack
Implementation Method 2
a wet etching process is performed on the first protection material layer to form the first protection layer and the notch and to expose a portion of the SOT layer and the top surface of the MTJ stack
Data Source
AI summary
A magnetic memory including a substrate, a spin-orbit torque (SOT) layer, a magnetic tunnel junction (MTJ) stack, a first protection layer, and a second protection layer is provided. The SOT layer is located over the substrate. The MTJ stack is located on the SOT layer. The first protection layer and the second protection layer are located on the sidewall of the MTJ stack. The first protection layer is located between the second protection layer and the MTJ stack. There is a notch between the second protection layer and the SOT layer.