Elastic Guide Blade Structure for High-Stiffness Long-Stroke Positioning
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Solution Overview
Problem
The existing elastic guiding devices in lithographic apparatuses face challenges in supporting increased mass and accommodating larger strokes without incurring higher stresses and fatigue, particularly due to the limitations of leaf springs in terms of stiffness and displacement ratios.
Innovation Solution
The proposed elastic guiding device incorporates a design featuring blades with integrated rigid and leaf spring elements, where the leaf spring elements extend over the complete length of the blades, and a cross flexure connection between the blades, along with torsion reinforcement and rounded recesses to reduce stress peaks, allowing for increased stiffness in the vertical direction while maintaining low stiffness in horizontal directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the mass of the balance mass is increased to reduce reaction force transfer, then the stiffness requirement increases, but the stroke capability is reduced due to stress and fatigue limits
Solution Approach 1:
The blade is segmented into multiple leaf spring elements stacked together, where each leaf spring element can independently deflect. This segmentation allows the structure to accommodate larger strokes by distributing the deflection across multiple elements, while still supporting increased mass through their combined stiffness.
Solution Approach 2:
The blade combines rigid elements with leaf spring elements to create a composite structure. The rigid elements provide structural support and stiffness to handle increased mass, while the leaf spring elements provide flexibility for larger strokes, resolving the contradiction between stiffness and stroke capability.
2Force
If the stiffness of the leaf springs is increased to support increased mass, then the load-bearing capacity improves, but the disturbance effect in horizontal direction increases
Solution Approach 1:
The blade structure implements local quality by having rigid elements and leaf spring elements in specific locations. The leaf spring elements are positioned to provide vertical compliance for supporting mass, while the overall blade geometry and rigid elements ensure that horizontal stiffness remains controlled to minimize disturbance effects.
Solution Approach 2:
The solution addresses the stiffness-disturbance contradiction by differentiating between vertical and horizontal dimensions. The leaf spring elements are configured to provide high vertical stiffness for mass support while maintaining low horizontal stiffness to reduce disturbance, effectively decoupling the stiffness requirements in different directions.
3Adaptability or versatility
If the stroke of the balance mass is increased to follow stage movements, then the adaptability improves, but the stress and fatigue in leaf springs increase
Solution Approach 1:
By dividing the blade into multiple leaf spring elements, the total stroke requirement is distributed across multiple segments. Each leaf spring element experiences reduced individual stress compared to a single-element design, while the cumulative deflection of all elements accommodates the required larger stroke, improving reliability.
Solution Approach 2:
The blade structure is designed to be dynamically adaptable through its leaf spring elements that can deflect elastically. This dynamic flexibility allows the balance mass to follow stage movements with increased stroke while the elastic deformation of the leaf springs absorbs stress, reducing fatigue compared to rigid connections.
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 design enhances the ability to support increased mass and accommodate larger strokes with reduced stress and fatigue, maintaining performance by balancing stiffness in vertical and horizontal directions, thus improving the reliability and operational range of the guiding device.
Implementation Method 1
The leaf springs provide sufficient stiffness in the vertical direction to support the balance mass in vertical direction to overcome gravity forces
Implementation Method 2
at least one of the bottom end and the top end comprises a rounded recess to reduce stress peaks in the material of the at least one leaf spring element
Data Source
AI summary
The invention relates to elastic guiding device to support a mass with respect to a base in a support direction, wherein the stiffness in support direction compared to stiffness in other direction, for example the stiffness in vertical direction compared to the stiffness in horizontal directions is substantially increased. The invention further relates to a positioning device comprising at least one elastic guiding device, and a lithographic apparatus comprising such positioning device.