Lithography Stage Feed-Forward Disturbance Compensation
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Solution Overview
Problem
Conventional lithographic apparatuses face a trade-off between throughput and overlay quality due to internal dynamic vibrations and disturbance forces affecting substrate stage positioning accuracy, which hinders high-speed and precise position control.
Innovation Solution
A position control system that includes a position measurement system, set-point generator, comparator, controller, feed-forward device, and actuator, where the feed-forward device uses a disturbance force correction table to estimate and compensate for disturbance forces, enhancing positioning accuracy and speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If higher accelerations are used to increase throughput, then productivity is improved, but manufacturing precision deteriorates due to larger internal dynamic vibrations and deformations of the stages
Solution Approach 1:
The system performs preliminary action by measuring disturbance forces at multiple positions before the actual positioning operation, storing these measurements in a lookup table, and then using this pre-acquired data to compensate for vibrations during high-speed movement. This allows the system to maintain high throughput while correcting positioning accuracy in real-time based on pre-characterized disturbance patterns.
Solution Approach 2:
The system implements feedback by continuously measuring the actual position of the substrate stage with a position measurement system, comparing it with the desired position, and using this error information along with disturbance force data to adjust control signals. This closed-loop feedback enables the system to maintain positioning accuracy even during high-acceleration operations that generate vibrations.
2Manufacturing precision
If conventional position control systems are used, then device complexity is kept simple, but manufacturing precision deteriorates due to un补偿ed disturbance forces affecting positioning accuracy and settling time
Solution Approach 1:
The system performs preliminary characterization of disturbance forces at different positions and stores this data in advance. During operation, it simply looks up the pre-measured disturbance force data and applies compensation, avoiding the need for complex real-time disturbance force calculations while still achieving improved positioning accuracy.
Solution Approach 2:
The system introduces an intermediary lookup table that stores pre-measured disturbance force data as a function of position. This intermediary structure mediates between the simple position measurement and the complex disturbance force compensation, allowing accurate compensation without requiring complex real-time physics calculations.
Data Source
AI summary
A position control system to control the position of a movable object, including a position measurement system configured to determine an actual position related quantity of the movable object; a set-point generator to provide a position related set-point signal of the movable object; a comparator to provide an error signal on the basis of a comparison of the actual position related quantity and the position related set-point signal, a controller to provide a control signal on the basis of the error signal, a feed-forward device to provide a feed-forward signal on the basis of the position related set-point signal, and one or more actuators to act on the movable object on the basis of the control signal and the feed-forward signal, wherein the feed-forward device includes a disturbance force correction table including estimations of disturbance forces exerted on the movable object in dependence of a position of the movable object.