EUV Reticle Placement Control for Contamination Avoidance
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Solution Overview
Problem
In lithographic apparatuses using extreme ultraviolet (EUV) radiation, contamination particles between the electrostatic clamp and the object cause wear and overlay issues, potentially leading to damage, especially with increased acceleration and heating factors.
Innovation Solution
A system that includes an illumination system, a support structure with burls, a projection system, and a controller to determine contamination locations on the object's backside and adjust its position or move burls to avoid contact with contamination, ensuring secure and wear-minimized coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the object is clamped to the support structure using burls, then secure holding is achieved, but wear and damage occur due to contamination particles at contact points
Solution Approach 1:
The system performs preliminary imaging to detect contamination particles on the backside of the patterning device before clamping occurs. The controller uses this advance information to determine a safe clamping position that avoids contamination, preventing wear and damage before they can occur during the clamping operation.
Solution Approach 2:
The solution moves from a single-point clamping approach to a multi-point burl array configuration. By distributing multiple burls across different locations on the support structure, the system can select optimal contact points that avoid contamination particles, effectively adding spatial dimensionality to the clamping strategy.
2Reliability
If contamination particles are present between the electrostatic clamp and the object, then wear and overlay issues occur, but cleaning or removing particles adds complexity to the system
Solution Approach 1:
The system performs preliminary imaging to detect contamination particles on the backside of the patterning device before clamping occurs. The controller uses this advance information to determine a safe clamping position that avoids contamination, preventing wear and damage before they can occur during the clamping operation.
Solution Approach 2:
The imaging system and controller act as intermediaries between the contamination particles and the clamping mechanism. Rather than directly addressing the contamination issue through cleaning or removal, the system uses imaging data to mediate the clamping process by selecting contact points that naturally avoid contamination, thus maintaining overlay precision without adding complex contamination management procedures.
3Productivity
If the patterning device is accelerated with increased force, then productivity improves, but wear and damage from contamination particles is exacerbated
Solution Approach 1:
The system performs preliminary imaging to detect contamination particles on the backside of the patterning device before clamping occurs. The controller uses this advance information to determine a safe clamping position that avoids contamination, preventing wear and damage before they can occur during the high-acceleration operation.
Solution Approach 2:
The system replaces purely mechanical clamping with a智能化 approach that combines imaging, computational analysis, and controlled positioning. Instead of relying solely on mechanical force distribution, the system uses optical detection and computational determination of safe contact points, substituting mechanical trial-and-error with a more sophisticated control mechanism that prevents contamination-related damage during high-acceleration operations.
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
Effectively prevents wear and damage by accurately positioning the object to avoid contamination contact with the burls, maintaining precise alignment and reducing maintenance needs in EUV radiation environments.
Implementation Method 1
an electrostatic clamp may be used to clamp an object, such as a patterning device and/or a substrate to a structure of the lithographic apparatus
Data Source
AI summary
A system designed to couple a patterning device to a support structure having a plurality of burls includes a camera module, an actuator, and a controller. The camera module is designed to capture image data of a backside of the patterning device. The actuator is coupled to at least one burl of the plurality of burls and is designed to move the at least one burl. The controller is designed to receive the image data captured from the camera module and determine one or more locations of contamination on the backside of the patterning device from the image data. The controller is also designed to control the actuator to move the at least one burl of the plurality of burls away from the one or more locations of contamination on the backside of the patterning device, based on the determined locations of contamination.