Lithography Sub-Field Control for Higher-Order Overlay Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current lithographic processes face limitations in controlling higher-order overlay errors and ensuring pattern fidelity due to dynamic effects, with existing correction models being insufficient or optimized, and there is a need for improved control methods to guarantee geometrical integrity during patterning operations.
Innovation Solution
A method involving the decomposition of initial spatial profiles into reticle and scanner components for co-optimization, allowing for better correction of spatial variations, and the use of co-optimized control strategies for reticle and scanner processes to address overlay errors and improve pattern fidelity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If existing correction models are used for lithographic processes, then the control of overlay errors is maintained at current levels, but the ability to correct higher-order overlay errors and ensure pattern fidelity is insufficient
Solution Approach 1:
The patent segments the exposure field into multiple sub-fields and decomposes the spatial profile into different component profiles (first component spatial profile and second component spatial profile). This segmentation allows independent optimization of each sub-field and component, enabling correction of higher-order overlay errors without requiring a single complex correction model for the entire field.
Solution Approach 2:
The patent applies different control strategies to different sub-fields based on their specific spatial profiles. By obtaining initial spatial profiles for each sub-field and decomposing them into component profiles, the system tailors the correction approach to local characteristics, improving overlay error correction precision while maintaining manageable model complexity through localized rather than global optimization.
2Manufacturing precision
If a single spatial profile is used for controlling the lithographic apparatus, then the control process is simple, but the correction of spatial variations across the exposure field is insufficient
Solution Approach 1:
The patent divides the exposure field into multiple sub-fields and obtains initial spatial profiles for each sub-field separately. This segmentation enables the system to capture local spatial variations that would be averaged out in a single global profile, improving correction precision while keeping each individual sub-field profile manageable in complexity.
Solution Approach 2:
The patent adds a dimensional aspect to the control approach by decomposing the spatial profile into multiple component profiles (first component spatial profile and second component spatial profile). This decomposition into different dimensional components allows the system to address various types of spatial variations independently, improving overall correction capability without requiring a single overly complex profile.
3Reliability
If dynamic effects during patterning are not considered, then the control process is simpler, but pattern fidelity and geometrical integrity cannot be guaranteed
Solution Approach 1:
The patent performs preliminary characterization of the exposure field by obtaining initial spatial profiles and decomposing them into component profiles before the actual patterning process. This preliminary action captures the static spatial variations and allows the control system to pre-compensate for them, ensuring pattern fidelity while keeping the real-time control process simpler by separating static characterization from dynamic control.
Data Source
AI summary
A method for controlling a lithographic apparatus configured to pattern an exposure field on a substrate including at least a sub-field, the method including: obtaining an initial spatial profile associated with a spatial variation of a performance parameter associated with a layer on the substrate across at least the sub-field of the exposure field; and decomposing the initial spatial profile into at least a first component spatial profile for controlling a lithographic apparatus at a first spatial scale and a second component spatial profile for controlling the lithographic apparatus at a second spatial scale associated with a size of the sub-field, wherein the decomposing includes co-optimizing the first and second component spatial profiles based on correcting the spatial variation of the performance parameter across the sub-field.