Semiconductor Seal Ring Layout for Moisture Protection and Etch Uniformity
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Solution Overview
Problem
Existing seal ring structures in semiconductor wafers are not robust enough to provide adequate protection against moisture degradation and ionic contamination, leading to issues such as over etching and dishing during fabrication processes.
Innovation Solution
A seal ring structure with a transition region designed to buffer the differences between the circuit and seal ring regions, featuring active regions, gate stacks, and conductive rings that are oriented and dimensioned differently to provide a smooth transition and enhanced protection, including concentric seal rings and transition lines with varying properties to mitigate processing issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional seal ring structure is used, then the fabrication process is simple, but the protection against moisture degradation and ionic contamination is insufficient
Solution Approach 1:
The seal ring structure is divided into multiple segments including inner seal rings, outer seal rings, and transition regions with different pattern densities. Each segment serves a specific function: inner seal rings provide primary protection, outer seal rings provide secondary protection, and transition regions buffer the differences between them. This segmentation allows the structure to achieve robust protection while maintaining manageable complexity through modular design.
Solution Approach 2:
Different regions of the seal ring structure are assigned different properties: the inner seal ring region has high pattern density for strong protection, the outer seal ring region has low pattern density for stress relief, and transition regions have intermediate pattern densities. This local differentiation optimizes protection effectiveness in critical areas while reducing overall structural complexity.
2Reliability
If the seal ring region has low pattern density, then the protection is stronger, but dishing and uneven etching occur during fabrication
Solution Approach 1:
Transition regions are introduced as intermediary zones between the high-density inner seal ring region and the low-density outer seal ring region. These transition regions have intermediate pattern densities that gradually buffer the abrupt changes, serving as mediators that prevent dishing and uneven etching while maintaining the protective function of the seal ring structure.
Solution Approach 2:
The pattern density parameter is varied continuously across different regions of the seal ring structure. The inner seal ring region maintains high pattern density for strong protection, while the outer seal ring region uses low pattern density to avoid fabrication defects. Transition regions employ intermediate pattern densities to ensure etching uniformity and prevent dishing, thus optimizing both protection strength and manufacturing precision through parameter optimization.
3Reliability
If the seal ring structure is made robust with multiple layers, then protection is improved, but processing defects like dishing increase
Solution Approach 1:
The multi-layer seal ring structure is segmented into distinct functional regions: inner seal rings for primary protection, transition regions for buffering, and outer seal rings for secondary protection. This segmentation allows each layer to be optimized independently, reducing processing defects like dishing while maintaining robust overall protection through the coordinated function of multiple layers.
Solution Approach 2:
Different layers and regions of the seal ring structure are assigned different pattern densities and structural properties tailored to their specific functions. The inner layers use higher pattern densities for strong protection, while outer layers use lower pattern densities to minimize processing defects. This local quality differentiation enables the multi-layer structure to achieve robust protection without increasing processing defects.
Data Source
AI summary
The present disclosure provides a semiconductor structure that includes a substrate having a circuit region and a seal ring region around the circuit region; first active regions of a first width W1 formed in the circuit region; second active regions of a second width W2 formed in the seal ring region; first gate stacks disposed on the first active regions in the circuit region and extending to isolation features; and second gate stacks disposed on the second active regions in the seal ring region and completely landing on the second active regions. The second width is greater than the first width, and each of the second active regions is a continuous ring shape to enclose the circuit region.