Segmented Seal Ring Layout to Cut EUV Mask Cost
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Solution Overview
Problem
The high cost and turn-around-time of semiconductor manufacturing, particularly due to the expensive photomasks required for extreme ultraviolet (EUV) lithography, necessitate a reduction in the number of photomasks used during the device development stage, while also requiring more flexible circuit designs as semiconductor device dimensions decrease.
Innovation Solution
The implementation of a semiconductor device design that includes separate first and second circuits, each surrounded by lower seal ring structures connected by connecting seal ring structures, allowing for the use of less expensive deep ultraviolet (DUV) lithography for upper seal ring formation, reducing the need for expensive EUV lithography and enabling flexible design options.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If EUV lithography is used for manufacturing test photo masks, then manufacturing precision is improved, but manufacturing cost increases
Solution Approach 1:
The seal ring structure is divided into two segments: lower seal rings formed by EUV lithography and upper seal rings formed by DUV lithography. This segmentation allows each part to be manufactured with the most appropriate lithography method, reducing overall cost while maintaining necessary precision where required.
Solution Approach 2:
The upper seal rings are designed to be formed by less expensive DUV lithography instead of expensive EUV lithography. These upper seal rings serve their protective function and can be manufactured with lower-cost equipment, reducing the overall manufacturing cost of test photo masks.
2Ease of manufacture
If the number of photomasks is reduced, then manufacturing cost decreases, but manufacturing precision may be compromised
Solution Approach 1:
The seal ring formation process is segmented into two stages using two different lithography methods. EUV lithography is used for the lower seal rings where high precision is critical, while DUV lithography is used for the upper seal rings where slightly lower precision is acceptable. This segmentation reduces the total number of high-cost EUV photomasks needed while maintaining overall manufacturing precision.
Solution Approach 2:
Different quality levels of lithography are applied to different parts of the seal ring structure. The lower seal rings receive high-quality EUV lithography for maximum precision, while the upper seal rings receive standard-quality DUV lithography. This local differentiation of quality allows cost reduction without compromising the precision required for critical components.
3Area of moving object
If circuit dimensions are reduced, then device density increases, but design flexibility decreases
Solution Approach 1:
The seal ring structure is designed with dynamic adaptability through the combination of lower and upper seal rings. The upper seal rings can be selectively formed or modified using DUV lithography, allowing the design to be adapted for different circuit configurations and testing requirements even as device dimensions are reduced.
Solution Approach 2:
The segmented seal ring structure allows independent optimization of different parts. As device dimensions are reduced, the lower seal rings provide the necessary structural integrity while the upper seal rings can be configured flexibly to accommodate different circuit layouts and testing needs, maintaining design flexibility despite miniaturization.
Data Source
AI summary
A semiconductor device includes a first circuit area disposed over a substrate and enclosed by a first seal ring structure, a second circuit area disposed over the substrate and enclosed by a second seal ring structure, an internal scribe line disposed between the first circuit area and the second circuit area, and connecting seal structures connecting the first seal ring structure and the second seal ring structures such that a part of the first seal ring structure, a part of the second seal ring structure and the connecting seal structures enclose the internal scribe line.