Corner Seal Ring Alignment Mark Layout Without Dummy APs
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Solution Overview
Problem
Existing seal ring structures and alignment marks in semiconductor technologies are prone to damage during fabrication processes, which can impact the assembly alignment and overall performance of integrated circuits (ICs).
Innovation Solution
The proposed semiconductor structure incorporates a seal ring region with corner seal ring (CSR) structures that eliminate patterns of dummy conductive pads over top metal lines. The CSR structures include a bridge section and an L-shaped section with an alignment mark, ensuring that the areas between these sections are free of dummy aluminum pads (APs), thereby reducing defects and improving alignment accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If alignment marks are formed on chips during fabrication, then assembly alignment can be achieved, but the alignment marks may be damaged by unhealthy processes impacting alignment accuracy
Solution Approach 1:
The alignment mark is formed as an integral part of the seal ring structure during the same fabrication process, rather than being added separately afterward. This preliminary integration ensures the alignment mark is created under controlled conditions and remains protected throughout subsequent fabrication steps, preventing damage that would compromise alignment accuracy
2Ease of manufacture
If dummy conductive pads are used in seal ring structures, then manufacturing completeness is maintained, but defects increase and alignment accuracy deteriorates
Solution Approach 1:
The invention extracts and eliminates the dummy conductive pads from the seal ring structure, retaining only the essential alignment mark features. By removing the unnecessary dummy pads that cause defects, the structure achieves both manufacturing simplicity and high alignment precision, as the alignment mark remains intact without interference from defective dummy elements
3Object-affected harmful factors
If seal ring structures are formed during fabrication, then protection from moisture and contamination is achieved, but alignment marks may be damaged during the same processes
Solution Approach 1:
The alignment mark and seal ring structure are merged into a single integrated formation process. Both structures are created simultaneously during the same fabrication steps, ensuring that the seal ring provides protection while the alignment mark remains intact as part of the same protected structure, eliminating the conflict between protection and mark integrity
Data Source
AI summary
Seal ring structures having alignment marks are disclosed herein. An exemplary semiconductor structure includes a seal ring surrounding a circuit region and a corner seal ring (CSR) structure at an interior corner of the seal ring. The CSR structure includes a bridge section between a first edge and a second edge of the seal ring, an L-shaped section between the seal ring and the bridge section and between the first edge and the second edge of the seal ring, a first area between the seal ring and the L-shaped section, and a second area between the L-shaped section and the bridge section. The seal ring includes a first top metal line and an aluminum pad (AP) disposed over and connected to the first top metal line. The L-shaped section includes a second top metal line having an L-shape. The first area and the second area are free of dummy AP.