Optical Element Fluid Purging With Anti-Back-Flow Nozzles
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Solution Overview
Problem
Conventional fluid purging systems in lithographic apparatuses suffer from stagnation points and back-flow, leading to contamination of optical elements, which reduces their lifespan and degrades radiation beam uniformity.
Innovation Solution
A fluid purging system with a fluid guiding unit comprising a first and second nozzle unit, where the second nozzle unit counters the Venturi effect, and micro-sieve outlets and tilted portions enhance fluid flow uniformity and directionality, minimizing contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fluid flow is provided to the micro-environment, then the system is simple to operate, but stagnation points are generated leading to contamination of optical elements
Solution Approach 1:
The fluid guiding unit is divided into multiple wall portions (first wall portion, second wall portion, third wall portion) with different orientations. Each wall portion has nozzles configured to direct fluid flow along specific contours, segmenting the overall flow path into controlled segments that prevent stagnation while maintaining structural manageability.
Solution Approach 2:
Different wall portions are configured with different local characteristics - the first wall portion has nozzles directing flow along a first contour, the second wall portion has nozzles directing flow along a second contour, and the third wall portion has nozzles directing flow along a third contour. This local differentiation ensures optimized flow patterns at each location to prevent stagnation points.
2Reliability
If conventional fluid flow is provided to the micro-environment, then the device complexity is low, but back-flow of contamination occurs
Solution Approach 1:
The fluid guiding unit is divided into multiple wall portions (first wall portion, second wall portion, third wall portion) with different orientations. Each wall portion has nozzles configured to direct fluid flow along specific contours, segmenting the overall flow path into controlled segments that prevent stagnation while maintaining structural manageability.
Solution Approach 2:
The fluid guiding unit is designed to preemptively counteract back-flow by configuring wall portions with specific orientations and nozzle arrangements. The third wall portion with nozzles directing flow along a third contour specifically addresses back-flow prevention before contamination can occur, applying preliminary anti-action to the Venturi effect and other back-flow mechanisms.
3Productivity
If fluid flow is optimized to reduce stagnation points, then purging performance improves, but the device complexity increases
Solution Approach 1:
The fluid guiding unit is divided into multiple wall portions (first wall portion, second wall portion, third wall portion) with different orientations. Each wall portion has nozzles configured to direct fluid flow along specific contours, segmenting the overall flow path into controlled segments that prevent stagnation while maintaining structural manageability.
Solution Approach 2:
The fluid guiding unit utilizes three-dimensional spatial arrangement with wall portions oriented at different angles and contours. The nozzles are configured to direct fluid flow along three-dimensional contours that wrap around or adjacent to the optical element, adding a dimensional aspect to flow control that enhances purging performance while keeping the structure manageable.
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
The system provides improved purging performance by reducing stagnation points and back-flow, enhancing the lifespan of optical elements and maintaining radiation beam uniformity.
Implementation Method 1
providing a more shielding and laminar type of flow
Implementation Method 2
Back-flow may also occur in conventional systems where fluid containing contaminants reverses direction, for example by the Venturi-effect
Data Source
AI summary
The present invention provides a fluid purging system (100) for an optical element (120), comprising a fluid guiding unit arranged to guide a fluid, provided by a fluid supply system, over at least a curved portion of an optical surface (122) of the optical element. The fluid guiding unit comprises a fluid inlet and a first nozzle unit (110) for providing a fluid to the optical surface. The fluid guiding unit being formed by at least a first wall portion (102) and at least a second wall portion (104), wherein the second wall portion being configured to face the optical surface and to follow a contour of the optical surface. The second wall portion comprises a second nozzle unit (112).