Lithographic Apparatus Vibration Isolation and Stage Positioning
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Solution Overview
Problem
Lithographic apparatuses face stage positioning errors due to resonances in components during measurement of the substrate's position relative to the optical elements, leading to inaccuracies in pattern application on substrates.
Innovation Solution
The implementation of a lithographic apparatus with a positioning stage supported by a supporting frame, isolated via a first vibration isolation system, and an isolation frame isolated via a second vibration isolation system, allowing direct measurement of the stage's position in one or more degrees of freedom relative to the isolation frame, thereby reducing resonances and positioning errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the positioning stage is moved to transfer patterns on substrates, then productivity is improved, but resonances occur in measurement components leading to stage positioning errors
Solution Approach 1:
The system is divided into two separate measurement systems: a first measurement system that measures the positioning stage position (which moves with the stage during pattern transfer), and a second measurement system that measures the projection system position (which remains stationary). This segmentation allows each measurement system to operate in its own reference frame, eliminating the resonance problem that occurs when a single measurement system tries to measure both moving and stationary components simultaneously.
2Measurement precision
If the projection system is kept stationary for stable measurement, then measurement precision is improved, but the positioning stage movement causes resonances in the measurement system
Solution Approach 1:
The first measurement system acts as an intermediary that measures the positioning stage position relative to the moving stage, while the second measurement system measures the projection system position relative to the stationary environment. By introducing these intermediate measurement systems, the patent eliminates the direct coupling between stage movement and projection system measurement, thereby preventing resonance while maintaining measurement precision.
3Device complexity
If a single measurement system is used for both positioning stage and projection system, then device complexity is reduced, but stage positioning errors occur due to resonances
Solution Approach 1:
The patent implements a dynamic measurement architecture where the first measurement system is dynamically coupled to the positioning stage (moving with it), while the second measurement system remains statically coupled to the projection system. This dynamic configuration allows the measurement system to adapt to the motion state, eliminating resonance-induced errors that would occur in a static single-system configuration, while the complexity increase is justified by the significant improvement in manufacturing precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration significantly reduces stage positioning errors by effectively isolating vibrations and improving the accuracy of position measurements, enhancing the precision of pattern application on substrates.
Implementation Method 1
isolating vibrations between the supporting frame and a first frame of a projection system using a first vibration isolation system
Implementation Method 2
isolating vibrations between the first frame and an isolation frame coupled to the first frame using a second vibration isolation system
Data Source
AI summary
A lithographic apparatus comprising: a positioning stage (WT); an isolation frame (300); a projection system (PS), comprising a first frame (210); a second frame (220); a supporting frame (10) for supporting the positioning stage; a first vibration isolation system (250) and a second vibration isolation system (270), wherein the supporting frame and the first frame are coupled via the first vibration isolation system; a stage position measurement system (400) to determine directly the position of a stage reference of an element of the positioning stage in one or more degrees of freedom with respect to an isolation frame reference of an element of the isolation frame; and wherein the first frame and the isolation frame are coupled via the second vibration isolation system.