Lithographic Base Frame Compliant Coupling Vibration Isolation
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Solution Overview
Problem
Conventional lithographic apparatuses face challenges in accurately isolating the projection system from vibrations caused by the stage assembly, which can lead to displacement and reduced pattern accuracy.
Innovation Solution
A lithographic apparatus with a base frame that includes a compliant portion connecting the stage assembly and projection system, allowing for dynamic decoupling and improved vibrational isolation through a deformable seal or flexible coupling, thereby mitigating the propagation of vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the projection system is rigidly mounted to the base frame, then structural stability is improved, but vibration isolation deteriorates
Solution Approach 1:
The base frame is segmented into a first portion supporting the stage assembly and a second portion supporting the projection system, connected by a compliant portion. This segmentation allows the two portions to move independently, isolating the projection system from stage-induced vibrations while maintaining overall structural stability.
Solution Approach 2:
The compliant portion of the base frame has different stiffness characteristics compared to the rigid portions. By changing the mechanical parameter (stiffness) of the connecting structure, the system achieves vibration isolation while maintaining structural integrity. The compliant portion allows controlled deformation to absorb vibrations.
2Object-affected harmful factors
If vibration isolators are used to separate the projection system, then vibration isolation is improved, but structural rigidity deteriorates
Solution Approach 1:
The compliant portion acts as an intermediary element between the first and second portions of the base frame. It mediates the transmission of vibrations by providing a controlled compliance path, isolating the projection system without requiring separate vibration isolator components that would compromise structural rigidity.
3Manufacturing precision
If the base frame is made completely rigid, then manufacturing precision is improved, but vibration propagation worsens
Solution Approach 1:
Different portions of the base frame have different mechanical qualities. The first and second portions are made rigid to ensure manufacturing precision and pattern accuracy, while the connecting portion is made compliant to prevent vibration propagation. This local differentiation of mechanical properties allows both precision and vibration isolation.
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 solution effectively reduces the impact of vibrations on the projection system, enhancing the accuracy and stability of pattern projection onto substrates by dynamically isolating the stage assembly-induced vibrations.
Implementation Method 1
In order to isolate vibrations due to movements of the stage apparatus from propagating to the projection system
Implementation Method 2
the first portion and the second portion being connected to each other via a compliant portion of the base frame
Data Source
AI summary
A lithographic apparatus is described, the lithographic apparatus comprising:an illumination system configured to condition a radiation beam;a support constructed to support a patterning device, the patterning device being capable of imparting the radiation beam with a pattern in its cross-section to form a patterned radiation beam;a projection system configured to project the patterned radiation beam onto a target portion of a substrate,a stage assembly comprising:a substrate table constructed to hold the substrate; anda positioning device configured to displace the substrate table relative to the projection system;a base frame onto which stage assembly and the projection system are mounted;the base frame comprising a first portion configured to support the stage assembly and a second portion configured to support the projection system, the first portion and the second portion being connected to each other via a compliant portion of the base frame.