Optical Element Cleaning via Dynamic Fluid Flow Patterns

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Solution Overview

Problem

Optical elements in systems like EUV light sources accumulate debris, which hinders performance and requires cleaning methods that do not disrupt the operating environment.

Innovation Solution

A fluid flow control system that directs a fluid, potentially containing free radicals, to an optical element using multiple flow patterns to remove debris by moving stagnation regions and combining with debris through etching or reaction, allowing for in-situ cleaning without system downtime.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a single fluid flow pattern is used to clean the optical element, then the cleaning process is simple, but debris accumulates in stagnation regions and cleaning is incomplete

Engineering Contradiction:

Improvesimplicity of cleaning processVSAvoidcompleteness of debris removal

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent applies dynamics by switching between multiple fluid flow patterns (first flow pattern and second flow pattern) during the cleaning process. The system dynamically changes the flow characteristics to move stagnation regions to different locations, ensuring comprehensive debris removal without requiring complex manual intervention.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The cleaning process uses periodic action by alternately applying different flow patterns in sequences. The system periodically switches between flow patterns to prevent debris accumulation in any single stagnation region, achieving thorough cleaning through repeated cyclic operations.

Inventive Principle:

Principle #19Periodic action

2Reliability

If the optical element is removed from the system for cleaning, then cleaning can be thorough, but system downtime increases and productivity decreases

Engineering Contradiction:

Improvethoroughness of cleaningVSAvoidsystem downtime

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The optical element performs self-service cleaning by being cleaned in-situ within the optical system. The fluid delivery system directs cleaning fluid directly to the optical element without requiring removal, allowing the system to clean itself and maintain continuous operation.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The cleaning system is designed with multi-functionality to perform both cleaning and operational functions within the same system environment. The fluid delivery mechanism serves dual purposes: maintaining the optical element during operation and cleaning it when needed, eliminating the need for separate cleaning operations.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If multiple flow patterns are used to remove all debris, then cleaning completeness improves, but control complexity increases

Engineering Contradiction:

Improvecompleteness of debris removalVSAvoidcomplexity of flow control system

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The cleaning process is segmented into distinct phases using different flow patterns. Each flow pattern addresses specific regions or types of debris accumulation, dividing the complex cleaning task into manageable segments that can be executed sequentially or alternately.

Inventive Principle:

Principle #1Segmentation

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 removes debris from optical elements within EUV light sources and similar systems, maintaining performance and efficiency while minimizing downtime for cleaning.

Implementation Method 1

The free radical can combine or react with the material to thereby remove the material from the surface through one of combustion of the material, etching of the material, or reaction with the material

Methodology Applied

Scientific EffectCombustion: Combustion

Implementation Method 2

Methodology Applied

Scientific EffectEtching:

Implementation Method 3

Methodology Applied

Scientific EffectChemical reaction:

Implementation Method 4

the fluid directed based on the first flow pattern moving at least some of the debris to a first stagnation region at the surface of the optical element

Methodology Applied

Scientific EffectFluid flow:

Data Source

PatentUS10232413B2Controlled fluid flow for cleaning an optical element

Publication Date: 2019.03.19 ASML NETHERLANDS BV

AI summary

A fluid is directed toward a surface of an optical element based on a first flow pattern, the surface of the optical element including debris and the fluid directed based on the first flow pattern moving at least some of the debris to a first stagnation region at the surface of the optical element; and the fluid is directed toward the optical element based on a second flow pattern, the fluid directed based on the second flow pattern moving at least some of the debris to a second stagnation region on the surface of the optical element, the second stagnation region and the first stagnation region being different locations at the surface of the optical element. Directing the fluid toward the surface of the optical element based on the second flow pattern removes at least some of the debris from the first stagnation region.