Overlay Misregistration Error Estimation in Metrology Targets
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Solution Overview
Problem
Current imaging overlay metrology systems lack a comprehensive method to accurately estimate and incorporate overlay misregistration errors from region of interest (ROI) measurements, leading to inefficiencies in evaluating target quality and combining error sources, which affects measurement fidelity and process accuracy.
Innovation Solution
A method that calculates overlay misregistration error estimations from analyzed ROI measurements using computer processors, providing a weighted and continuous assessment of target quality, enabling the integration of error evaluations across different sources and levels, and allowing for improved process corrections and trade-offs between accuracy and throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If overlay misregistration error estimations are calculated and incorporated from ROI measurements, then measurement precision and reliability are improved, but device complexity and processing time increase
Solution Approach 1:
The patent divides the metrology target into multiple regions of interest (ROIs) and calculates overlay misregistration error estimations for each ROI separately. This segmentation allows the system to process and evaluate different areas independently, improving measurement precision while managing complexity through modular processing of individual ROI measurements before combining results.
2Reliability
If comprehensive error estimation from all ROI measurements is performed, then measurement fidelity improves, but productivity and throughput decrease
Solution Approach 1:
The patent applies partial action by selectively processing and evaluating ROI measurements based on their quality and relevance. Not all ROI measurements are treated equally - the system identifies and processes only the necessary measurements required for accurate overlay estimation, avoiding unnecessary processing of defective or redundant measurements, thus maintaining measurement fidelity while improving throughput.
Solution Approach 2:
The patent implements continuous improvement of measurement fidelity by iteratively refining error estimations. The system continuously monitors measurement quality and adjusts processing depth accordingly, ensuring that measurement fidelity improves progressively without requiring complete reprocessing of all data, thereby maintaining productivity.
3Manufacturing precision
If target quality is continuously assessed using error estimations, then manufacturing precision improves, but loss of time in processing increases
Solution Approach 1:
The patent performs preliminary calculations of overlay misregistration error estimations for each ROI measurement during the initial measurement process. By pre-calculating these error estimations as part of the standard measurement workflow rather than as a separate post-processing step, the system incorporates quality assessment into the measurement process itself, improving manufacturing precision without adding significant processing time.
Data Source
AI summary
Systems and methods are provided, which calculate overlay misregistration error estimations from analyzed measurements of each ROI (region of interest) in at least one metrology imaging target, and incorporate the calculated overlay misregistration error estimations in a corresponding estimation of overlay misregistration. Disclosed embodiments provide a graduated and weighted analysis of target quality which may be integrated in a continuous manner into the metrology measurement processes, and moreover evaluates target quality in terms of overlay misregistration, which forms a common basis for evaluation of errors from different sources, such as characteristics of production steps, measurement parameters and target characteristics. Such common basis then enables any of combining various error sources to give a single number associated with measurement fidelity, analyzing various errors at wafer, lot and process levels, and/or to trade-off the resulting accuracy for throughput by reducing the number of measurements, in a controlled manner.