Elongated Flexure Support for Microlithography Optics
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Solution Overview
Problem
Existing support structures for optical elements in microlithography, such as hexapods, face limitations in accuracy and range due to high-rise configurations and ball-joint articulations, leading to restricted movements and potential tilting errors under dynamic loading.
Innovation Solution
The support element is designed with elongated flexures transverse to their bending axis, allowing for increased cross-sectional area and moderate stresses, enabling high accuracy and large adjusting movements while preventing rotation around specific axes, thus enhancing control bandwidth and positional accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If simple leaf-spring-like support elements are used in hexapod configurations, then the structure is simple and easy to manufacture, but the support elements become comparatively high-rise perpendicular to the retainer plane, requiring nested manipulators and limiting optical element rotation
Solution Approach 1:
The patent changes the geometric parameters of the support element by introducing an elongated flexure design where the flexure extends significantly beyond the connection points. This transformation allows the support element to achieve the required support function with a much smaller overall height perpendicular to the retainer plane, eliminating the need for nested manipulators while maintaining structural simplicity.
2Area of stationary object
If ball-joint articulation is used to achieve compact adjusting kinematics, then the structure is small in area, but the flexures have low cross-sectional area causing high stresses under dynamic loading
Solution Approach 1:
The patent transitions from a two-dimensional ball-joint articulation to a three-dimensional elongated flexure structure. The flexure extends in a direction perpendicular to the traditional plane of the support element, creating additional spatial dimension. This dimensional change allows the flexure to have both a small projected footprint and a large cross-sectional area, simultaneously achieving compactness and high stress resistance.
Solution Approach 2:
The support element combines multiple functional regions within a single integrated structure: rigid connection regions for structural integrity, elongated flexure regions for controlled deformation with high cross-sectional area, and articulation points for movement. This composite design allows different parts to serve different functions optimally, achieving both compactness and strength.
3Area of stationary object
If ball-joint articulation is used for compact design, then the structure occupies small area, but tilting motions falsify the position of the articulation point, reducing positioning accuracy
Solution Approach 1:
The patent extracts the tilting motion function from the articulation point itself and relocates it to the elongated flexure region. The flexure is designed to accommodate controlled deformation and tilting in its elongated section, while the articulation points remain fixed and precise. This separation ensures that the measurement-critical articulation points do not experience position falsification from tilting motions.
4Speed
If high accelerations are permitted for large adjusting movements, then the adjusting range and speed are improved, but the limited cross-sectional area of flexures causes overloading and reduces lifetime
Solution Approach 1:
The patent fundamentally changes the cross-sectional area parameter of the flexure by designing it to be significantly larger than in traditional ball-joint configurations. The elongated flexure design provides ample cross-sectional area to handle high dynamic loads, allowing the system to achieve large adjusting movements with high accelerations without overloading the support elements, thereby extending their operational lifetime.
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 allows for high accuracy and extended adjusting ranges with long lifetimes of the support elements, reducing tilting errors and enabling larger accelerations without overloading, thereby improving the positioning and orienting of optical elements.
Implementation Method 1
a support member (114) which is connected via a first connection element (113, 115) to an external support unit (110) and via a second connection element (113, 115) to the optical element (106.1)
Data Source
AI summary
Support elements for an optical element and a method for supporting an optical element are disclosed. The disclosure can be used in connection with arbitrary optical apparatuses or optical imaging methods. In particular, the disclosure can be used in connection with the microlithography employed in the manufacture of microelectronic circuits.