Multi-Patterning Overlay Alignment via Intermediary Layer
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Solution Overview
Problem
Conventional overlay control methods in semiconductor fabrication are unable to align a physical layer directly to a pattern formed via multi-patterning photolithography, leading to displacement errors and misalignment issues, which affect the electrical contact between structures in integrated circuits.
Innovation Solution
The method involves determining a displacement vector between two physical layers used in multi-patterning operations, calculating the center position of the pattern based on this vector, and aligning a third physical layer to the pattern center using a registration vector derived from measurable vectors and a transformation matrix.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multi-patterning photolithography is used to achieve smaller critical dimensions, then manufacturing precision is improved, but alignment accuracy between layers deteriorates due to displacement errors
Solution Approach 1:
The patent introduces an intermediary alignment layer between the physical layers that forms the multi-patterning pattern. This alignment layer serves as a mediator to capture and transfer the pattern center information, enabling accurate alignment of subsequent physical layers without directly measuring the multi-patterning pattern itself. The intermediary layer resolves the measurement difficulty by providing a measurable reference that indirectly represents the pattern center.
Solution Approach 2:
The patent creates a copy of the multi-patterning pattern center information by forming an alignment layer that replicates the pattern's central features. Instead of directly measuring the complex multi-patterning pattern, the system creates a simplified copy (the alignment layer) that contains the essential alignment information, making measurement feasible while maintaining alignment accuracy.
2Ease of operation
If conventional overlay control methods are used, then process simplicity is maintained, but alignment accuracy deteriorates due to inability to align to multi-patterning patterns
Solution Approach 1:
The patent segments the alignment process into distinct stages: first forming the multi-patterning pattern, then forming a separate alignment layer based on that pattern, and finally using the alignment layer for subsequent layer alignment. This segmentation allows conventional overlay control methods to be applied to the alignment layer while achieving accurate alignment to the multi-patterning pattern, effectively decoupling the complexity of multi-patterning from the alignment measurement process.
3Manufacturing precision
If multi-patterning operations are performed to achieve pitch splitting, then manufacturing capability is improved, but device complexity increases due to multiple pattern layers
Solution Approach 1:
The patent extracts the alignment information from the complex multi-patterning pattern by forming a dedicated alignment layer that contains only the essential pattern center features. This extraction separates the alignment function from the product-forming layers, allowing the multi-patterning process to focus on creating the desired pitch-split pattern while the alignment layer handles the alignment measurement function, thereby reducing the functional complexity of each individual layer.
Data Source
AI summary
Methods of aligning a number of physical layers to a pattern formed via multi-patterning are disclosed. A method may include determining a misalignment vector between a first layer and a second layer used to form a pattern via multi-patterning. The method may also include calculating, based on the misalignment vector between the first layer and the second layer, a center position of the pattern. Further, the method may include aligning a third layer to center position of the pattern. A computing system and a processing system are also described.