Lithography Process Control Using Edge Placement Error Feedback
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Solution Overview
Problem
Current semiconductor manufacturing processes face challenges in accurately determining control parameters for lithographic processes, particularly in reproducing patterns with dimensions smaller than the classical resolution limit, leading to difficulties in achieving desired electrical functionality and performance.
Innovation Solution
A method is developed to determine control parameters by obtaining images of substrate features, calculating image-related metrics such as edge placement error (EPE), and adjusting process parameters to minimize EPE, which involves controlling lithographic and further processes like resist coating, baking, and etching based on these metrics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional lithographic projection is used to manufacture patterns, then manufacturing process can be maintained with standard equipment, but manufacturing precision deteriorates for dimensions smaller than the classical resolution limit
Solution Approach 1:
The patent implements a feedback mechanism where measured feature dimensions from manufactured patterns are fed back to adjust control parameters for subsequent lithographic processes. This closed-loop approach continuously improves pattern reproduction accuracy by using actual measurement data to refine exposure conditions, resolving the contradiction between maintaining standard equipment and achieving sub-resolution precision.
Solution Approach 2:
The patent systematically varies control parameters such as exposure dose, focus position, and numerical aperture to optimize pattern formation for sub-resolution features. By establishing relationships between control parameters and resulting feature dimensions, the method enables precise control of manufacturing outcomes without requiring complex equipment modifications.
2Manufacturing precision
If control parameters are adjusted to improve pattern accuracy, then manufacturing precision improves, but measurement precision requirements increase to detect and minimize edge placement errors
Solution Approach 1:
The patent performs preliminary measurements and calculations of edge placement errors before final pattern manufacturing. By predicting EPE values using process models and adjusting control parameters in advance, the system compensates for anticipated measurement challenges and achieves better edge placement accuracy without requiring ultra-precise real-time measurement capabilities.
Solution Approach 2:
The patent introduces computational models and simulation tools as intermediaries between physical measurement and control parameter adjustment. These models predict edge placement errors based on process conditions and provide guidance for parameter optimization, reducing the direct burden on measurement precision while improving manufacturing accuracy.
Data Source
AI summary
A method including: obtaining an image of at least part of a substrate, wherein the image includes at least one feature manufactured on the substrate by a manufacturing process including a lithographic process and one or more further processes; determining one or more image-related metrics in dependence on a contour determined from the image, wherein one of the one or more image-related metrics is an edge placement error, EPE, of the at least one feature; and determining one or more control parameters of the lithographic process and/or the one or more further processes in dependence on the edge placement error, wherein at least one control parameter is determined so as to minimize the edge placement error of the at least one feature.