Excimer Chamber Window Purge Flow for Metal Fluoride Dust Control

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Solution Overview

Problem

Metal fluoride dust accumulation on optical windows of master oscillator, power amplifier, and power ring amplifier in lithographic apparatuses leads to optical damage and reduced discharge voltage, affecting laser performance and shortening the service life of these components.

Innovation Solution

A window housing apparatus with an insert and aperture apparatus configured to control gas flow rates, trapping metal fluoride dust and directing clean gas to reduce dusting on optical windows, while maintaining efficient purge without increasing clean gas backflow rates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If metal fluoride trap is used to remove dust, then optical damage is reduced, but clean gas backflow rate increases

Engineering Contradiction:

Improveoptical window durabilityVSAvoidclean gas backflow rate

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

A baffle plate is introduced as an intermediary component between the metal fluoride trap and the optical window. The baffle plate intercepts metal fluoride dust particles in the gas flow, preventing them from reaching the optical window while allowing the majority of clean gas to pass through to the optical window area, thus reducing dust accumulation without requiring high backflow rates

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The gas flow path is segmented into multiple zones: a first region with higher clean gas concentration from the trap, and a second region near the optical window. The baffle plate creates this segmentation, allowing dust removal in the first region while maintaining adequate (but not excessive) clean gas flow to the second region, reducing the overall backflow rate requirement

Inventive Principle:

Principle #1Segmentation

2Object-affected harmful factors

If gas flow rate is increased to purge dust, then dusting on optical windows is reduced, but energy consumption increases

Engineering Contradiction:

Improvemetal fluoride dustingVSAvoidgas circulation energy

Core Design Contradiction:

Object-affected harmful factorsVSUse of energy by moving object

Solution Approach 1:

The baffle plate serves as a passive intermediary that provides dust removal functionality without requiring additional energy input. It physically intercepts dust particles through its structure, eliminating the need to increase gas flow velocity and associated energy consumption while still protecting the optical window

Inventive Principle:

Principle #24Intermediary (Mediator)

3Object-affected harmful factors

If uniform gas flow distribution is achieved, then dusting is reduced, but device complexity increases

Engineering Contradiction:

Improvemetal fluoride dustingVSAvoidflow distribution control

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

Instead of attempting uniform flow distribution across the entire optical window surface, the baffle plate provides localized protection at critical areas where dust accumulation is most harmful. This local quality approach reduces dusting effectively while maintaining simple overall device structure without complex flow control mechanisms

Inventive Principle:

Principle #3Local quality

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

Reduces metal fluoride dusting on optical windows, improving flow distribution, and extending the service life of the metal fluoride trap and master oscillator components by controlling gas flow and purging effectively.

Implementation Method 1

a metal fluoride trap coupled to the chamber and configured to trap metal fluoride dust generated from the chamber

Methodology Applied

Scientific EffectAdsorption: Adsorption

Implementation Method 2

an aperture apparatus coupled to the window housing and comprising a plurality of cells configured to trap metal fluoride dust flowing upstream from the chamber through the aperture apparatus toward the optical window

Methodology Applied

Scientific EffectPhysical barrier filtration: Filter (physical)

Implementation Method 3

The insert is configured to control a first flow rate of the clean gas along the optical window and a second flow rate of the clean gas through the aperture apparatus

Methodology Applied

Scientific EffectFlow control through restricted passage:

Data Source

PatentUS12476432B2Directed gas purge to reduce dusting of excimer discharge chamber windows

Publication Date: 2025.11.18 CYMER INC

AI summary

A light source apparatus includes a chamber and a metal fluoride trap coupled to the chamber and configured to provide clean gas to a set of window housing apparatuses coupled to the chamber. Each window housing apparatus is configured to reduce metal fluoride dusting on an optical window and includes a window housing supporting an optical window, an aperture apparatus coupled to the window housing, and an insert disposed between the aperture apparatus and the optical window. The aperture apparatus includes a plurality of cells configured to trap metal fluoride dust flowing upstream from the chamber through the aperture apparatus toward the optical window. The insert is configured to control a first flow rate of the clean gas along the optical window and a second flow rate of the clean gas through the aperture apparatus.