Lithographic Object Support Actuating Structures for Slip Prevention
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Solution Overview
Problem
Current lithographic apparatuses face limitations in applying forces due to differential pressure, clamping surface area, and friction coefficient, leading to potential slip and exposure precision issues, especially at higher accelerations and speeds.
Innovation Solution
A support structure with a chuck and actuating structures, including a first and second actuating structure, where the second actuating structure is movable to apply a pushing force to the object, utilizing a spring and linear actuator to maintain constant force and prevent slip, independent of differential pressure and friction coefficient limitations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If vacuum clamping is used to hold the patterning device, then the device can be secured to the chuck, but the available clamping force is limited by differential pressure, clamping surface area, and friction coefficient
Solution Approach 1:
The positioning system is divided into two independent parts: a vacuum clamping system for holding the patterning device and a separate actuating structure for applying pushing forces. This segmentation allows each subsystem to be optimized independently, with the actuating structure providing additional force without being constrained by vacuum pressure limitations.
Solution Approach 2:
The actuating structure serves as an intermediary mechanism that applies additional forces to the patterning device through contact with its sides. This intermediary force application system supplements the vacuum clamping force, enabling higher accelerations and speeds without compromising positioning stability.
2Productivity
If higher accelerations and speeds are used to increase throughput, then productivity improves, but the existing clamping system may experience slip due to insufficient force
Solution Approach 1:
The actuating structures are designed to be dynamically adjustable, allowing the pushing forces to be modified in real-time based on the required accelerations and speeds. This dynamic force adjustment enables the system to maintain positioning stability across a wide range of operating conditions, from low-speed precision work to high-speed throughput operation.
Solution Approach 2:
The system changes the force parameters by introducing additional pushing forces through the actuating structures. By independently controlling these forces separate from the vacuum pressure, the system can optimize the total applied force to match the demands of different operating modes without affecting the vacuum clamping integrity.
3Force
If the clamping surface area is increased to generate more normal force, then the friction force increases, but the available surface area is limited by the patterning device size and pattern area
Solution Approach 1:
Instead of increasing clamping force solely through the vacuum interface area (2D limitation), the system adds a third dimension of force application by using actuating structures that contact the sides of the patterning device. This dimensional expansion allows additional force generation without being constrained by the limited top surface area available for vacuum clamping.
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
Enhances the ability to apply forces without slip, maintaining exposure precision and overlay accuracy even at higher accelerations and speeds, by decoupling force application from differential pressure and friction coefficient limitations.
Implementation Method 1
The spring is configured to apply force to the linear actuator to move the linear actuator relative to the chuck
Implementation Method 2
depositing the patterning device on a clamp having one or more vacuum pads and applying a vacuum to pull and generate a normal force between the patterning device and the vacuum pad
Implementation Method 3
The normal force then generates friction force between the vacuum pad and the patterning device
Data Source
AI summary
A support structure for positioning an exchangeable object in a lithographic apparatus. The support structure has a chuck to support and clamp the object and an actuating structure. The actuating structure may have a first actuating structure (e.g., spring) and a second actuating structure (e.g., linear actuator). The first actuating structure is moveable relative to the chuck and is configured to move the second actuating structure between a first position in contact with a side of the object and a second position out of contact with the side of the object. The second actuating structure is configured to move at least a portion thereof relative to the first actuating structure between a first position in contact with the side of the object and a second position out of contact with the side of the object and to apply a pushing force to the side of the object.