Nonvolatile Memory Misalignment Correction via Dummy Region Patterns
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Solution Overview
Problem
Existing memory devices face challenges in accurately controlling misalignment during photo alignment, which can lead to rotation and distortion issues, affecting the efficiency and accuracy of memory cell placement.
Innovation Solution
A nonvolatile memory device is designed with a cell block region, a core region containing control logic, and a dummy region with a correction block that includes specific patterns of metal lines and vias to measure and correct alignment errors, utilizing eccentric and concentric patterns to determine minute misalignments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photo alignment is performed without correction patterns, then manufacturing process is simpler, but misalignment accuracy deteriorates
Solution Approach 1:
The correction block with metal lines and vias is constructed in advance during the manufacturing process, establishing reference patterns before actual memory cell fabrication. These pre-formed patterns enable measurement and correction of alignment errors, improving manufacturing precision without adding complex real-time correction mechanisms.
Solution Approach 2:
The correction block serves as an intermediary element between the manufacturing process and the final memory device. By introducing this intermediate structure with known geometric relationships, the system can measure alignment deviations and apply corrections, effectively mediating between fabrication imperfections and precise device performance.
2Measurement precision
If correction block is added to measure alignment errors, then misalignment control accuracy is improved, but device complexity increases
Solution Approach 1:
The correction block is segmented into distinct functional components: metal lines extending in specific directions, vias connecting different layers, and intentional gap structures. This segmentation allows each element to serve a specific measurement function while keeping the overall structure manageable and systematic rather than monolithic and complex.
Solution Approach 2:
The correction block implements local quality variations through intentional gap structures at specific locations between metal lines and vias. These localized features create measurable alignment sensitivity in critical areas without requiring the entire structure to be complex, enabling precise measurement where needed while maintaining simplicity elsewhere.
Data Source
AI summary
A memory device includes a cell block including memory cells; a control logic; and a correction block in a dummy region in a core region. The correction block may include first metal lines extending in a first direction; vias extending in a second direction; and second metal lines extending in a third direction. Each of the second metal lines may have a metal center line defining a center of each of the second metal lines in the first direction. Each of the vias may have a via center line defining a center of each of the vias in the first direction. At least one metal center line and at least one via center line may be spaced apart from each other by a first gap in the first direction.