Wrap-Around MRAM Top Electrode for Deep Trench Integration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current MRAM structures face limitations in trench depth and aspect ratio, which hinder the integration of MRAM into advanced node technologies due to voiding issues during metal fill and the risk of encapsulation erosion leading to device shorts.
Innovation Solution
The proposed solution involves embedding the MRAM device completely within an Mx+1 metal line, utilizing a metallic cap layer as a selective cap to protect the encapsulation and enable deeper trench depths, thus reducing the aspect ratio of Vx vias and preventing voiding during copper fill.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the trench depth is increased to accommodate taller MRAM structures, then the integration into advanced node technologies is enabled, but the aspect ratio of Vx vias increases leading to voiding issues during metal fill
Solution Approach 1:
The patent segments the trench structure by introducing a wrap-around top electrode that extends laterally beyond the MTJ stack footprint. This segmentation allows the trench to be filled in a controlled manner, reducing void formation during copper fill while accommodating increased trench depth for taller MRAM structures.
Solution Approach 2:
The top electrode is extended into the lateral dimension (beyond the vertical axis), creating a wrap-around structure that provides mechanical support and electrical connectivity. This dimensional extension reduces the aspect ratio impact on via fill reliability while enabling deeper trenches.
2Length of moving object
If the trench depth is increased to accommodate taller MRAM structures, then the integration into advanced node technologies is enabled, but encapsulation erosion occurs leading to device shorts
Solution Approach 1:
The wrap-around top electrode structure serves as a protective cushion that prevents encapsulation erosion before it can lead to device shorts. By extending the electrode laterally, it provides a buffer zone that absorbs mechanical stress and prevents direct contact between the encapsulation and aggressive metallization layers.
Solution Approach 2:
The patent employs a composite structure combining the top electrode material with the encapsulation layer in a wrap-around configuration. This composite approach creates a more robust interface that resists erosion from adjacent metallization, protecting the underlying MTJ stack from shorts.
3Device complexity
If the upper word line is positioned above the bottom electrode, then the device structure is simplified, but the lower horizontal surface of the upper word line is above the bottom electrode creating potential shorting paths
Solution Approach 1:
Instead of positioning the upper word line entirely above the bottom electrode, the patent inverts the conventional approach by allowing the upper word line to wrap around and extend below the bottom electrode level. This inverted positioning eliminates direct shorting paths while maintaining structural simplicity.
Data Source
AI summary
A semiconductor device including a magnetic tunnel junction (MTJ) stack and an upper word line of the MTJ stack surrounding vertical side surfaces of the MTJ stack. A semiconductor device including a magnetic tunnel junction (MTJ) stack and an upper word line for the MTJ stack surrounding vertical side surfaces and an upper surface of a reference layer of the MTJ stack. A method including forming a forming a magnetic tunnel junction (MTJ) stack and forming a dielectric encapsulation layer surrounding vertical side surfaces of a top electrode, a free layer, a tunneling barrier, a reference layer and a bottom electrode of the MTJ stack.