Multi-Level Via Bypasses MTJ Interconnect Area
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Solution Overview
Problem
The integration of magnetic tunnel junctions (MTJs) in interconnection structures for advanced technology nodes faces challenges in terms of area efficiency and protection during fabrication, particularly in the back-end-of-line (BEOL) processing, where MTJs are formed amidst complex metallization levels.
Innovation Solution
The implementation of a multi-level via that electrically bypasses conductive paths of the second interconnection level, allowing the MTJ device to be confined within the second interconnection level, thereby reducing the need for short horizontal lines and protecting the MTJ during polishing processes, while enabling flexible integration and efficient use of space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If conventional single-level vias are used to connect interconnection levels, then the interconnection structure follows standard fabrication processes, but additional horizontal conductive lines are required in the second interconnection level which reduces area efficiency and increases complexity near MTJ devices
Solution Approach 1:
The patent transitions from conventional single-level vias to multi-level vias that extend vertically across multiple interconnection levels (first, second, and third levels) without requiring intermediate horizontal connections. This dimensional approach allows the via to bypass the second interconnection level directly, eliminating the need for additional horizontal conductive lines and reducing area requirements near MTJ devices.
Solution Approach 2:
The invention extracts and removes the unnecessary horizontal conductive lines from the second interconnection level by implementing multi-level vias that provide direct vertical connectivity. This extraction eliminates redundant conductive paths, reducing both area consumption and structural complexity in the interconnection network.
2Reliability
If MTJ devices are integrated with standard interconnection levels, then fabrication processes are straightforward, but the MTJ devices lack protection during polishing processes such as chemical mechanical polishing (CMP)
Solution Approach 1:
The patent implements a multi-level via structure where the via extends through the second interconnection level and provides inherent protection to the MTJ device during polishing processes. The via structure acts as a protective element that prevents damage to the MTJ device during chemical mechanical polishing, eliminating the need for separate protection layers or processes.
Solution Approach 2:
The multi-level via serves multiple functions simultaneously: it provides electrical connectivity between the first and third interconnection levels, bypasses the second interconnection level, and protects the MTJ device during fabrication processes. This multi-functionality integrates protection and connectivity into a single structural element, simplifying the overall fabrication process.
3Ease of operation
If the MTJ device height matches the second interconnection level height, then the MTJ device can be completely accommodated within the second interconnection level, but the via structure becomes more complex requiring additional horizontal interconnects
Solution Approach 1:
The patent resolves the conflict between MTJ accommodation and via simplicity by extending the via into the third interconnection level. This vertical extension allows the via to connect directly to the top layer of the MTJ device without requiring intermediate horizontal connections in the second level, maintaining structural simplicity while ensuring proper accommodation.
Solution Approach 2:
The multi-level via is segmented into distinct portions: a first via contact portion connecting to the bottom layer, extending through the second interconnection level, and a second via contact portion connecting to the top layer in the third interconnection level. This segmentation allows each portion to serve its specific function without requiring complex intermediate connections.
Data Source
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AI summary
Disclosed is a device, comprising: a first interconnection level (110) including a first dielectric layer (112) and a first set of conductive paths (111) arranged in the first dielectric layer, a second interconnection level (120) arranged on the first connection level and including a second dielectric layer (122) and a second set of conductive paths (121) arranged in the second dielectric layer, a third interconnection level (130) arranged on the second interconnection level and including a third dielectric layer (132) and a third set of conductive paths (131) arranged in the third dielectric layer, a magnetic tunnel junction, MTJ, device (140) including a bottom layer (142), a top layer (146) and an MTJ structure (144) arranged between the bottom layer and the top layer, wherein the bottom layer is connected to a bottom layer contact portion (116) of the first set of conductive paths and the top layer is connected to a top layer contact portion (135) of the second or third set of conductive paths, and a multi-level via (150) extending through the second dielectric layer and the third dielectric layer, between a first via contact portion (118) of the first set of conductive paths and a second via contact portion (138) of the third set of conductive paths, wherein a height of the MTJ device corresponds to, or is less than, a height of the multi-level via.