Dynamic Feed-Forward Parameter Adaptation for Lithography Overlay
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Solution Overview
Problem
Current feed-forward control systems in lithographic apparatuses are inadequate for accurately compensating for time-varying conditions, leading to residual errors in overlay and focus due to static calibration parameters that are not updated frequently enough, resulting in increased overlay errors and reduced accuracy in feature formation.
Innovation Solution
A method to dynamically adapt feed-forward parameters by calculating corrections based on measured overlay and alignment error data using a Hybrid sampling scheme, allowing for real-time updates and improved compensation for reticle, lens, and substrate heating effects, thereby reducing residual errors and enhancing the accuracy of pattern reproduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If static calibration parameters are used in feed-forward control systems, then device complexity is reduced and ease of operation is improved, but manufacturing precision deteriorates due to residual overlay errors from time-varying conditions
Solution Approach 1:
The patent transforms static calibration parameters into dynamic parameters that are continuously adapted during substrate processing. The system updates feed-forward parameters in real-time based on measured overlay errors, allowing the control system to respond to time-varying conditions such as thermal drift and mechanical changes, thereby improving manufacturing precision without requiring complete system redesign
Solution Approach 2:
The patent implements a feedback mechanism where measured overlay errors from metrology systems are fed back to continuously update and refine feed-forward control parameters. This closed-loop approach allows the system to learn from actual performance deviations and automatically adjust parameters to compensate for time-varying conditions, resolving the contradiction between simplicity and precision
2Manufacturing precision
If recalibration is performed frequently to maintain accuracy, then manufacturing precision is improved, but productivity deteriorates due to increased downtime and processing time
Solution Approach 1:
The patent enables continuous adaptation of calibration parameters during normal substrate processing operations, eliminating the need for periodic production stoppages for recalibration. The system continuously updates feed-forward parameters using real-time measurement data, maintaining high manufacturing precision while ensuring uninterrupted substrate throughput, thus resolving the contradiction between accuracy and productivity
3Reliability
If static feed-forward parameters are used, then ease of operation is maintained, but reliability deteriorates due to inability to compensate for time-varying conditions such as thermal drift and mechanical changes
Solution Approach 1:
The patent implements a self-service mechanism where the lithographic apparatus automatically updates its own calibration parameters using internal measurement systems and control algorithms. The system autonomously detects overlay errors and adjusts feed-forward parameters without requiring external intervention or manual recalibration, thereby improving reliability through continuous adaptation while maintaining ease of operation through automation
Data Source
AI summary
A method for correcting values of one or more feed-forward parameters used in a process of patterning substrates, the method including: obtaining measured overlay and/or alignment error data of a patterned substrate; and calculating one or more correction values for the one or more feed-forward parameters in dependence on the measured overlay and/or alignment error data.