Semiconductor Seal Ring Layout for CMP Dishing and Dicing Stress
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Solution Overview
Problem
Existing seal ring structures in semiconductor wafers face challenges in structure robustness and line density, particularly during dicing and chemical mechanical planarization (CMP) processes, due to the shrinkage of critical dimensions and increased metal routing density.
Innovation Solution
The introduction of a property enhancing structure (PES) comprising multiple groups of property enhancing rings (PERs) disposed between sections of the seal ring structure, which increases structure robustness and balances topography loading during processing, thereby reducing dishing in the seal ring region during CMP.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the critical dimension is shrunk to increase circuit density, then the line density is improved, but the structure robustness deteriorates
Solution Approach 1:
The seal ring structure is divided into multiple segments including inner seal rings, outer seal rings, and intermediate structures. This segmentation allows each component to be optimized independently for both density and robustness, with the inner seal rings providing density and the outer seal rings providing structural strength.
Solution Approach 2:
The seal ring structure employs composite material layers including dielectric layers, metal layers, and barrier layers. These composite structures provide both the high line density required for modern circuits and the mechanical robustness needed for dicing and CMP processes through the combined properties of different materials.
2Quantity of substance
If the metal routing density is increased to improve circuit functionality, then the line density is improved, but the structure robustness deteriorates
Solution Approach 1:
The metal routing is segmented into multiple discrete metal layers separated by dielectric layers. This allows high metal routing density within each layer while the overall segmented structure maintains robustness through the distributed architecture and intermediate support structures.
Solution Approach 2:
The solution moves from two-dimensional planar routing to three-dimensional stacked metal layers. This dimensional transition allows increased metal routing density by utilizing vertical space while maintaining structural robustness through the distributed three-dimensional architecture.
3Ease of manufacture
If the seal ring structure is simplified to reduce fabrication complexity, then the ease of manufacture is improved, but the structure robustness deteriorates
Solution Approach 1:
The seal ring is segmented into modular components that can be fabricated using standard semiconductor manufacturing processes. Each segment can be formed using conventional lithography and deposition techniques, maintaining ease of manufacture while the combined segmented structure provides enhanced robustness.
Solution Approach 2:
The seal ring structure is designed to perform multiple functions including mechanical support, electrical isolation, and stress management using the same basic structural elements. This multi-functionality reduces fabrication complexity by avoiding the need for separate specialized structures for each function.
4Productivity
If the seal ring structure is simplified to reduce fabrication steps, then the productivity is improved, but the line density deteriorates
Solution Approach 1:
Multiple structural functions are merged into integrated layers that serve both mechanical and electrical purposes. The dielectric and metal layers are combined in stacked configurations that provide both high line density and structural support in a single fabrication sequence, improving productivity while maintaining density.
Solution Approach 2:
The structure utilizes vertical stacking of multiple thin layers to achieve high line density without increasing planar complexity. This three-dimensional arrangement allows dense routing while maintaining fabrication efficiency through standard layer-by-layer processing techniques.
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.