Lithographic Position Control Using Continuous Weight Functions
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Solution Overview
Problem
Conventional lithographic apparatuses face challenges in achieving high performance position control due to the use of different position measurement systems or configurations across various operating areas, leading to reduced bandwidth and stability issues in position controllers.
Innovation Solution
A position control system is implemented with a combination of first and second controllers, applying a continuous weight function to convert input signals from different position measurement configurations, ensuring smooth transitions and enhanced stability across overlapping areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If different position measurement systems or configurations are applied throughout the overall operating area, then the entire operating area can be covered, but the bandwidth of the position controller is adversely affected
Solution Approach 1:
The overall operating area is divided into multiple operating areas, each with its own position measurement configuration. This segmentation allows each controller to be optimized for its specific area while maintaining overall system coverage.
Solution Approach 2:
The position control system dynamically switches between different position measurement configurations based on the current operating area. This dynamic adaptation allows the system to maintain high bandwidth and performance by selecting the appropriate measurement system for each specific operating region.
2Area of stationary object
If different position measurement systems are used in different operating areas, then area coverage is achieved, but controller performance and stability are reduced
Solution Approach 1:
The system dynamically selects and switches between different position measurement configurations based on the current operating area, ensuring that the most appropriate measurement system is always active. This dynamic approach maintains controller stability by avoiding abrupt transitions and ensuring smooth handovers between configurations.
Solution Approach 2:
The system continuously monitors the current operating area and uses this feedback to determine which position measurement configuration should be active. This feedback mechanism ensures stable transitions between different measurement systems and maintains overall controller stability.
3Reliability
If a single position measurement system is used throughout the overall operating area, then controller bandwidth is maintained, but the system becomes more complex and costly
Solution Approach 1:
Instead of using a single complex position measurement system throughout the entire operating area, the system segments the operating area into multiple regions, each with its own simplified position measurement configuration. This segmentation reduces the complexity of each individual measurement system while maintaining overall performance.
Solution Approach 2:
Each operating area is equipped with a position measurement configuration optimized for its specific requirements. This local optimization allows each measurement system to be simpler and more cost-effective, while the overall system maintains high performance through intelligent switching between configurations.
4Ease of manufacture
If different position measurement configurations are applied, then manufacturing limitations are addressed, but position control accuracy is adversely affected
Solution Approach 1:
The operating area is segmented into multiple regions, each with position measurement configurations that can be manufactured within practical limitations. This segmentation makes the system more manufacturable while maintaining accuracy through optimized local configurations.
Solution Approach 2:
The system dynamically selects the appropriate position measurement configuration for each operating area, ensuring that the most accurate measurement system is always active. This dynamic selection compensates for the use of different configurations and maintains overall position control accuracy.
Data Source
AI summary
A position control system includes a position measurement system including a first position measurement configuration arranged to determine a position of an object in a first operating area and a second position measurement configuration to determine a position of the object in a second operating area; and a control unit configured to control a position of the object, the control unit including a first and a second controller, the first and second controllers being arranged to convert an input signal representing a position of the object to a respectively first and second control signal, the control unit being arranged to determine a combined control signal for controlling the position of the object in an overlapping area of the first and second operating area, wherein the combined control signal is obtained by applying a continuous weight function to the first and second control signal.