Single Damascene Cobalt Interconnects for Low Resistance
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Solution Overview
Problem
As semiconductor devices are scaled to smaller dimensions, existing interconnect structures face challenges with high resistivity and electromigration issues, requiring barrier liners that increase electrical resistance and complicate fabrication processes.
Innovation Solution
The use of single damascene patterning processes to form cobalt contact and interconnect structures without liner interfaces, which reduces contact resistance and improves electromigration properties, allowing for direct overlay and lower aspect ratios in interconnect fabrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional interconnect structures with barrier liners are used, then electromigration properties are improved, but electrical resistance increases and device complexity increases
Solution Approach 1:
The patent removes the barrier liner layer from the interconnect structure, extracting the problematic interface that caused high resistance. The cobalt-based interconnect is used directly without requiring a separate barrier liner, thereby eliminating the resistance penalty while maintaining electromigration properties through the inherent characteristics of cobalt at scaled dimensions.
Solution Approach 2:
The patent changes the material parameter from conventional metals (copper, aluminum) to cobalt-based materials that exhibit superior electromigration resistance at nanoscale dimensions. This material substitution allows the interconnect to function without barrier liners while maintaining reliability, as cobalt's physical properties naturally resist electromigration effects at the scaled dimensions used in the invention.
2Reliability
If barrier liners are added to improve electromigration, then reliability is improved, but manufacturing complexity increases
Solution Approach 1:
The invention extracts and removes the barrier liner layer from the multi-layer fabrication process, simplifying the manufacturing sequence. By using cobalt-based materials that inherently resist electromigration at nanoscale, the process eliminates the need for additional deposition and patterning steps required for barrier liners, thereby reducing device complexity while maintaining reliability.
3Manufacturing precision
If dual damascene processes are used for interconnect fabrication, then overlay precision is improved, but manufacturing complexity and aspect ratio challenges increase
Solution Approach 1:
The patent segments the fabrication process into separate single damascene steps for contact and interconnect formation, allowing each to be optimized independently. This segmentation enables the use of simpler single damascene processes rather than complex dual damascene sequences, reducing overall manufacturing complexity while maintaining alignment precision through sequential processing and planarization steps.
Solution Approach 2:
The invention performs preliminary planarization and preparation steps before interconnect formation, creating a flat surface that simplifies subsequent single damascene patterning. This preliminary action eliminates the need for complex dual damascene overlay alignment by ensuring that the single damascene process can achieve precise alignment from a prepared baseline, thereby reducing manufacturing complexity.
4Area of moving object
If interconnect dimensions are scaled down, then device density is improved, but resistivity increases and electromigration worsens
Solution Approach 1:
The patent changes the material parameter to cobalt-based interconnects that exhibit superior electromigration resistance specifically at nanoscale dimensions. This parameter change allows the interconnect to maintain reliability despite scaled-down dimensions, as cobalt's physical properties naturally resist electromigration effects at the small dimensions required for high device density.
Data Source
AI summary
The present disclosure relates to semiconductor structures and, more particularly, to contact and interconnect structures and methods of manufacture. The structure includes: a single damascene contact structure in electrical contact with a contact of a source region or drain region; and a single damascene interconnect structure in a wiring layer and in direct electrical contact with the single damascene contact structure.