Semiconductor Metal Layer Layout for Electromigration at Wire Corners
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Solution Overview
Problem
In semiconductor devices, the concentration of current at the slopes of metal wires near corner portions can lead to electromigration (EM) failure, especially when the thickness of these slopes is small.
Innovation Solution
A semiconductor device configuration where the metal layer includes regions with specific geometries, such as a wire connection portion and plug connection portion, positioned away from corner portions with obtuse angles, reducing the occurrence of current concentration at slopes and thus minimizing the risk of EM failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the metal layer includes slopes with small thickness to reduce device complexity, then the manufacturing process is simplified, but current concentration occurs at the slopes leading to electromigration failure
Solution Approach 1:
The patent applies local quality by creating different regions within the metal layer: a first region with a first thickness and a second region with a second thickness greater than the first thickness. The second region is specifically positioned at locations prone to current concentration, providing enhanced reliability only where needed while maintaining overall structural simplicity.
Solution Approach 2:
The patent implements preliminary action by pre-positioning the thicker second region of the metal layer at locations where current concentration is expected to occur, such as near corner portions of wires. This preventive measure addresses electromigration risks before they manifest, ensuring reliability without requiring complex real-time monitoring or adjustment mechanisms.
2Manufacturing precision
If the metal layer thickness is reduced to improve manufacturing precision, then fabrication accuracy is enhanced, but the slopes become more susceptible to electromigration failure
Solution Approach 1:
The patent implements local quality by varying the thickness of the metal layer across different regions. The first region has a first thickness while the second region has a second thickness greater than the first, allowing precise control in the first region while providing enhanced reliability in the second region through increased thickness.
Solution Approach 2:
The patent applies parameter changes by modifying the thickness parameter of the metal layer. The thickness transitions from a first thickness in the first region to a second thickness in the second region, where the second thickness is greater than the first thickness. This parameter variation optimizes both manufacturing precision and electromigration resistance.
3Device complexity
If the metal layer geometry is simplified to reduce device complexity, then fabrication is easier, but current concentration occurs at corner portions leading to EM failure
Solution Approach 1:
The patent applies local quality by creating a second region with different properties (greater thickness) specifically at locations where current concentration occurs, such as near corner portions. This localized modification addresses the harmful effect without requiring complete geometric redesign of the entire metal layer.
Solution Approach 2:
The patent converts the harmful effect of current concentration into a benefit by strategically positioning the thicker second region of the metal layer at locations where current concentration occurs. The increased thickness in these specific areas transforms the vulnerable slopes into protected regions, turning the identified problem into a solution.
Data Source
AI summary
A semiconductor device includes a metal layer disposed above a transistor on a first substrate. The metal layer includes a first region extending in a first direction and a second region that has a width in the first direction smaller than the first region and protrudes from the first region in a second direction, and has a first corner portion having an angle larger than 180° as viewed in a third direction between a proximal end portion of the second region and the first region. The metal layer includes a first portion that is disposed within the first region and has a lower surface at a first height, and a second portion that is disposed within the second region and has a lower surface at a second height lower than the first height. A step present at a boundary between the first portion and the second portion is disposed away from an edge of the second region at a first position near the first corner portion in the second direction and adjacent to the edge of the second region at a second position away from the first corner portion than the first position.