Zigzag Metal Line Structure for Sub-30 Nm Interconnect Reliability
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Solution Overview
Problem
In semiconductor integrated circuits, particularly in BEOL structures with pitch sizes below 30 nm, the signal delay due to metal line resistance is unsustainable, and dielectric line wiggling occurs when filling trenches with high aspect ratio, especially when using non-copper conductive materials like ruthenium for metallization.
Innovation Solution
A wiring structure with metal lines having zigzag sidewalls is developed, maintaining a reasonable width from bottom to top with small variations, achieved through a multi-patterning process forming multiple sections with alternating outward and inward leaning sidewalls, and surrounded by different dielectric and barrier layers to prevent line wiggling and resistance issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If metal lines are filled in trenches with high aspect ratio to achieve high integration density, then the pitch size can be reduced below 30 nm, but dielectric line wiggling occurs and signal delay increases due to unsustainable resistance
Solution Approach 1:
The metal line is divided into multiple sections (first section, second section, third section, fourth section) with alternating sidewall orientations. Each section has sidewalls that lean in opposite directions, creating a zigzag pattern that segments the continuous metal line into controlled segments with different stress characteristics.
Solution Approach 2:
The sidewalls of adjacent metal line sections are made asymmetric by leaning in opposite directions. The first section has outward-leaning sidewalls while the second section has inward-leaning sidewalls, creating an asymmetric zigzag pattern that balances metal stress and prevents line wiggling.
2Stability of the object's composition
If trenches with high aspect ratio are filled to form metal lines, then vertical integration is improved, but metal stress causes dielectric line wiggling
Solution Approach 1:
The zigzag configuration with alternating outward and inward leaning sidewalls creates counterbalancing stress distributions. The outward-leaning sections counteract the inward-leaning sections, effectively neutralizing the cumulative metal stress that would otherwise cause dielectric line wiggling.
Solution Approach 2:
Instead of straight vertical sidewalls, the patent introduces curved zigzag sidewalls that alternate between outward and inward lean. This curvature pattern distributes metal stress more evenly throughout the structure, preventing localized stress concentration that causes line wiggling.
3Ease of manufacture
If metal lines with straight sidewalls are used, then manufacturing is simpler, but width variation from bottom to top becomes uncontrolled
Solution Approach 1:
Different sections of the metal line are given different local sidewall qualities - alternating between outward-leaning and inward-leaning orientations. This local variation in sidewall geometry allows precise control of the overall width while maintaining manufacturability through standard patterning processes.
Data Source
AI summary
Embodiments of present invention provide a wiring structure. The wiring structure includes a metal line in a dielectric layer, where the metal line has a first sidewall and a second sidewall opposite the first sidewall and, from a bottom to a top thereof, includes at least a first section and a second section, where first and second sidewalls of the first section lean outwards from a bottom to a top of the first section, and first and second sidewalls of the second section lean inwards from a bottom to a top of the second section. A method of manufacturing the wiring structure is also provided.