Guard Ring Interconnect Layout for Seam-Free IC Lithography
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Solution Overview
Problem
The challenge in integrated circuit manufacturing is forming fine featured components using high resolution optical lithography, which results in smaller field sizes and the formation of 'seam regions' where components cannot be printed due to alignment issues, leading to incomplete layers and reduced functionality.
Innovation Solution
The implementation of ring structures, such as guard rings or etch rings, within various layers of the integrated circuit, including inner and outer rings that wrap around components to protect them from external hazards and facilitate hermetic sealing, allowing for the use of different resolution optical lithography processes across layers without splitting the die, thus covering the entire area and preventing seam regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high resolution optical lithography is used to form fine featured components, then manufacturing precision is improved, but the field size is reduced and seam regions are formed
Solution Approach 1:
The patent divides the lithography process into multiple fields that are stitched together to form a complete die. Ring structures are strategically placed at the boundaries of these fields to facilitate alignment and stitching, enabling high resolution patterning across the entire die area without seam regions.
Solution Approach 2:
The ring structures serve as intermediary features that facilitate the stitching process between adjacent lithography fields. These rings provide alignment references and enable precise registration of patterned layers across field boundaries, eliminating seam regions while maintaining fine feature precision.
2Manufacturing precision
If the die is split into multiple fields for lithography, then fine features can be formed, but seam regions are created where components cannot be printed
Solution Approach 1:
The ring structures are formed in advance as part of the lithography pattern before subsequent processing steps. These pre-formed rings at field boundaries ensure that alignment and stitching can be performed accurately, preventing seam regions and ensuring complete layer coverage across the entire die.
Solution Approach 2:
The ring structures act as intermediary alignment features that mediate the stitching process between adjacent lithography fields. They provide physical references that enable precise registration, ensuring that no seam regions are created and that the complete die area is covered without gaps or defects.
3Reliability
If ring structures are added to protect components and enable hermetic sealing, then reliability is improved, but device complexity increases
Solution Approach 1:
The ring structures serve multiple functions simultaneously: they act as alignment references for lithography stitching, provide hermetic sealing barriers, and serve as guard rings for component protection. By combining these functions into a single structural element, the patent avoids adding separate features for each function, thereby limiting the increase in device complexity while achieving improved reliability.
Solution Approach 2:
The ring structures are strategically segmented and placed only at critical locations such as field boundaries and around sensitive components, rather than uniformly across the entire die. This selective placement provides necessary protection and sealing functions while minimizing the overall complexity and area occupied by ring structures.
Data Source
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AI summary
An integrated circuit structure includes a device layer including a first set of devices and a second set of devices. An interconnect layer is above the device layer, where the interconnect layer includes one or more conductive interconnect features within dielectric material. In an example, a first ring structure including conductive material extends within the interconnect layer, and a second ring structure including conductive material extends within the interconnect layer. In an example, the second ring structure is non-overlapping with the first ring structure. In an example, the first ring structure is above the first set of devices of the device layer, and the second ring structure is above the second set of devices of the device layer.