Exposure Stage Synchronous Control Using Feedforward Error Compensation
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Solution Overview
Problem
Existing exposure apparatuses, such as step-and-scan exposure systems, face challenges in suppressing synchronous errors between the reticle stage and the substrate stage, leading to increased position deviations and decreased exposure accuracy due to the inability to effectively synchronize the driving of these stages using conventional feedforward control methods.
Innovation Solution
A control apparatus is implemented that includes a feedback control system and a feedforward control system, where the feedforward control system calculates a feedforward manipulated variable based on the input/output response of the substrate stage and the synchronous error between the reticle and substrate stages, allowing for synchronized driving and reduced synchronous errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional feedforward control is applied to each stage independently, then position deviation of individual stages is reduced, but synchronous error between reticle stage and substrate stage increases
Solution Approach 1:
The patent combines the feedforward control of the reticle stage and substrate stage into a unified synchronous control system. The synchronous control unit integrates the feedforward manipulated variables from both stages and generates a coordinated control signal that maintains synchronous movement, thereby reducing synchronous error while maintaining individual position accuracy.
Solution Approach 2:
The patent implements feedback control by measuring the actual synchronous error between reticle stage and substrate stage, then using this error information to adjust the feedforward manipulated variables. The synchronous control unit continuously monitors position deviations and modifies the feedforward signals to minimize synchronous error, creating a closed-loop control system.
2Stability of the object's composition
If master-slave synchronous driving method is used, then coordination between reticle stage and substrate stage is improved, but synchronous error cannot be suppressed due to inability to control slave stage independently
Solution Approach 1:
The patent transforms the static master-slave relationship into a dynamic synchronous control system where both stages have independent feedforward control capabilities. The synchronous control unit dynamically adjusts the feedforward manipulated variables based on real-time synchronous error measurements, allowing the slave stage to be controlled independently while maintaining coordination with the master stage.
Solution Approach 2:
The patent changes the control parameters by introducing synchronous error as a new control variable. Instead of controlling only individual position deviations, the system now controls both position deviation and synchronous error simultaneously by adjusting the feedforward manipulated variables based on these combined parameters.
Data Source
AI summary
The present invention provides a control apparatus for performing synchronous control to synchronize driving of a second moving member so as to follow driving of a first moving member, including a feedforward control system that includes a calculator configured to obtain an input/output response of the second moving member and position deviations of the first moving member and the second moving member while driving the first moving member and the second moving member in synchronism with each other, and calculate a feedforward manipulated variable based on the input/output response of the second moving member and the synchronous error between the first moving member and the second moving member obtained from the position deviations of the first moving member and the second moving member.