Lithographic Overlay Mark Layout for Compact Yield Assessment
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Solution Overview
Problem
Lithographic marks occupy significant space on substrates and require time to create, while existing methods for designing these marks do not allow for precise determination of yield curves and other quality parameters.
Innovation Solution
A method for designing a mark comprising first and second layer components arranged in multiple overlay configurations with varying overlay distances, allowing for precise determination of yield curves by optimizing overlay distances and component numbers to minimize space and ensure precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If traditional mark designs are used, then the mark provides sufficient space for overlay configurations, but the mark occupies excessive substrate space and requires excessive creation time
Solution Approach 1:
The mark is segmented into multiple overlay configurations, where each configuration contains a subset of first layer components and second layer components. This segmentation allows the total mark to cover fewer overlay distances while maintaining sufficient statistical samples for yield curve determination, thereby reducing the overall substrate space occupied by the mark.
Solution Approach 2:
Instead of increasing the number of overlay configurations along a single distance dimension, the patent introduces multiple first layer components and second layer components within each overlay configuration. This dimensional shift from extending the mark along the overlay distance axis to expanding the number of components within each configuration allows precise yield curve determination with fewer overlay configurations, thus reducing substrate space.
2Measurement precision
If the number of overlay configurations is increased to improve yield curve precision, then measurement precision improves, but the mark occupies more substrate space and takes longer to create
Solution Approach 1:
The mark is divided into multiple overlay configurations, each containing multiple first layer components and second layer components. This segmentation allows achieving sufficient statistical precision through multiple components per configuration rather than requiring many configurations, thereby reducing the time needed to create and process the mark while maintaining yield curve determination accuracy.
Solution Approach 2:
The patent changes the parameters of the mark design by optimizing the number of first layer components and second layer components in each overlay configuration, as well as the overlay step between configurations. This parameter optimization enables achieving precise yield curve determination with a reduced total number of overlay configurations, thus decreasing mark creation time while maintaining measurement precision.
3Measurement precision
If more first layer components and second layer components are added to each overlay configuration, then yield curve precision improves, but the mark occupies more substrate space
Solution Approach 1:
The mark is segmented into multiple overlay configurations, each containing a manageable number of first layer components and second layer components. This segmentation distributes the total number of components across fewer overlay configurations, reducing the overall substrate space required while maintaining sufficient statistical precision for yield curve determination through the combined data from all configurations.
Solution Approach 2:
The patent shifts from increasing precision by extending the mark along the overlay distance dimension (more configurations) to increasing precision by adding components within each configuration. This dimensional change allows achieving high measurement precision with a more compact mark layout, thereby reducing substrate space occupation.
Data Source
AI summary
A non-transitory computer-readable medium stores a set of instructions for performing operations to design a mark for assessing a lithographic process. The operations include determining an overlay step that represents a difference between different overlay distances of the different overlay configurations for a design of the mark. The mark includes a first layer mark with first layer components and a second layer mark with second layer components. The first layer mark and the second layer mark are to be projected onto each other via the lithographic process. Each overlay configuration has different overlay distance at which each first layer component is arranged in a first direction of an associated second layer component of the second layer components. The operations include determining a largest overlay distance. The operations also include determining a number of first layer components and/or a number of associated second layer components in each overlay configuration.