Leaf Spring Guide Structure for Constant In-Plane Stiffness
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Solution Overview
Problem
The existing guiding devices in lithographic apparatuses experience a significant drop in in-plane stiffness when transitioning from a planar to a non-planar state, leading to inaccurate prevention of relative movements in orthogonal directions, which affects the precision of nozzle positioning in semiconductor manufacturing.
Innovation Solution
The proposed guiding device employs multiple leaf springs, with at least one in a non-planar state at equilibrium, ensuring a constant overall in-plane stiffness by shifting the stiffness contribution from planar to non-planar springs as they deform, preventing significant drops in stiffness and maintaining linear or rotational precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If two-dimensional plate-like leaf springs are used in the guiding device, then the device can guide linear movement in the displacement direction, but the in-plane stiffness drops significantly when the leaf spring deflects from planar to non-planar state
Solution Approach 1:
The patent transitions from two-dimensional plate-like leaf springs to three-dimensional shell-shaped leaf springs. The shell structure introduces a new dimensional aspect (curvature in multiple directions) that maintains stiffness while allowing deformation. The shell shape with principal radii of curvature enables the spring to deflect without losing in-plane stiffness, resolving the contradiction between guiding capability and stiffness maintenance.
Solution Approach 2:
The patent changes the geometric parameters of the leaf spring from flat 2D dimensions to 3D shell parameters including principal radii of curvature (R1, R2) and thickness. This parameter transformation allows the spring to maintain structural rigidity while accommodating the required deflection range, preventing the stiffness drop that occurs in planar springs during deformation.
2Length of moving object
If the leaf spring is allowed to deform from planar to non-planar state during movement, then the guiding device can achieve the required range of movement, but the in-plane stiffness becomes insufficient to prevent orthogonal movements
Solution Approach 1:
The shell-shaped leaf spring uses three-dimensional geometry with controlled principal radii of curvature to enable large deflections while maintaining in-plane stiffness. The curved shell structure distributes stress and maintains rigidity in the plane perpendicular to the displacement direction, even when deflected from the equilibrium position, thus preserving positioning accuracy throughout the range of movement.
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 maintains high in-plane stiffness throughout the range of movement, ensuring accurate linear or rotational movements without orthogonal displacements, thereby enhancing the precision and reliability of the nozzle positioning in lithographic apparatuses.
Implementation Method 1
at least one of the leaf springs is in a non-planar state when the spring device is in an equilibrium position... maintains high in-plane stiffness throughout the range of movement
Data Source
AI summary
An actuator, configured to move a first object with respect to a second object, that includes a first body having an annular ring, a second body, arranged movably with respect to the first body, having a longitudinal shaft at least partially disposed within the annular ring, and at least one spring device, arranged between the first body and the second body, wherein the at least one spring device is configured to guide relative movements between the first body and the second body in a range of movement, and the at least one spring device has two or more leaf springs, wherein each of the two or more leaf springs is connected to the first body and to the second body, and wherein at least one of the leaf springs is in a non-planar state when the spring device is in an equilibrium position.