Nested Seal Ring Structure for Dicing Stress and CMP Dishing
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Solution Overview
Problem
Existing seal ring structures in semiconductor wafers face challenges with reduced structure robustness and line density due to shrinking critical dimensions and metal routing density, impacting the dicing and chemical mechanical planarization processes.
Innovation Solution
A property enhancing structure (PES) is introduced, comprising multiple nested seal rings and property enhancing rings (PERs) with specific spacing and metal connections to enhance robustness and line density, mitigating stress and improving manufacturing processability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If circuit critical dimension shrinks and metal routing density increases, then device integration improves, but seal ring structure robustness deteriorates
Solution Approach 1:
The patent implements nested seal ring structures where inner seal rings are positioned within outer seal rings, creating multiple concentric protective barriers. This nesting approach enhances overall structure robustness by distributing mechanical stresses across multiple rings rather than relying on a single thick ring, thereby maintaining strength while accommodating smaller critical dimensions.
Solution Approach 2:
The seal ring structure is divided into multiple discrete rings rather than a single continuous ring. Each ring can be independently optimized for specific functions, and the segmented structure provides better stress distribution and flexibility, maintaining robustness even as individual ring dimensions shrink with reduced critical dimensions.
2Productivity
If circuit critical dimension shrinks and metal routing density increases, then device integration improves, but seal ring line density deteriorates
Solution Approach 1:
Multiple nested rings create overlapping patterns that increase effective line density when viewed from above. The concentric arrangement ensures that inspection and measurement systems can detect multiple lines within a given area, improving manufacturing precision control even as individual feature sizes shrink.
Solution Approach 2:
The patent extends the seal ring structure into the vertical dimension by creating multi-layer nested rings at different heights. This three-dimensional arrangement increases line density without requiring proportional increases in planar dimension, allowing better control of manufacturing precision as critical dimensions shrink.
3Ease of manufacture
If seal ring structure is simplified, then manufacturing ease improves, but dicing stress resistance deteriorates
Solution Approach 1:
The nested ring structure can be fabricated using standard multi-patterning processes already established in semiconductor manufacturing. Each ring is formed through sequential deposition and etching steps that leverage existing manufacturing capabilities, maintaining ease of manufacture while the nested configuration provides enhanced dicing stress resistance through distributed load bearing.
Solution Approach 2:
Dividing the seal ring into multiple segmented rings allows each segment to be optimized for stress resistance while maintaining compatibility with standard manufacturing processes. The segmented structure provides crack propagation barriers that enhance dicing stress resistance without requiring complex manufacturing steps.
4Ease of manufacture
If seal ring structure is simplified, then manufacturing ease improves, but CMP dishing control deteriorates
Solution Approach 1:
The nested ring configuration creates multiple concentric patterns that provide reference features for CMP process control. The overlapping circular patterns help distribute and visualize dishing effects, enabling better measurement and control of CMP uniformity while maintaining ease of manufacture through standard patterning processes.
Solution Approach 2:
By extending the seal ring structure into multiple vertical layers with nested configurations, the patent creates three-dimensional reference features that improve CMP dishing control. The multi-layer arrangement provides better depth resolution for measuring and controlling planarization uniformity without complicating the manufacturing process.
Data Source
AI summary
The present disclosure provides a semiconductor structure that includes dielectric layers disposed over a semiconductor substrate; and a seal ring structure formed in the dielectric layers and distributed in multiple metal layers. The seal ring structure further includes first metal lines of a metal layer disposed in a first area and longitudinally oriented along a first direction; second metal lines of the metal layer disposed in a second area and longitudinally oriented along the first direction; and metal bars of the metal layer disposed in the first area and longitudinally oriented along a second direction, the metal bars connecting the first metal lines.