Microlithography Optical System Catalytic Self-Cleaning
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Solution Overview
Problem
Microlithographic projection exposure apparatuses face contamination issues from hydrocarbons entering the optical system, leading to unwanted absorption and radiation disruption, which are difficult to prevent without interrupting the continuous operation and reducing throughput.
Innovation Solution
A microlithographic optical system with a catalytic or chemically active layer positioned outside the used beam path, utilizing stray electromagnetic radiation for self-cleaning, converting hydrocarbons into volatile molecules that can be removed, thereby avoiding contamination-related performance impairment without additional energy or process interruptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If intensive cleaning of optical elements is conducted to avoid contamination, then contamination is reduced, but the lithography process must be interrupted
Solution Approach 1:
A catalytic layer is applied in advance to optical components outside the beam path. This layer proactively converts hydrocarbon contaminants into volatile substances before they can accumulate and cause contamination, eliminating the need for interruptive cleaning while maintaining reliability
Solution Approach 2:
The catalytic layer performs self-cleaning by automatically converting hydrocarbon contaminants into volatile substances through catalytic action. The system serves itself by using the existing electromagnetic radiation field to drive the cleaning process without external intervention, thereby maintaining both reliability and continuous operation
2Reliability
If inert purge gases of maximum purity are used to prevent hydrocarbon entry, then contamination is reduced, but complete prevention is not achieved
Solution Approach 1:
The catalytic layer acts as an intermediary between hydrocarbon contaminants and the optical components. It provides a chemical transformation pathway that converts harmful hydrocarbons into harmless volatile substances, supplementing the purge gas system and achieving complete protection without increasing its complexity
3Reliability
If a catalytic layer is added to the optical system for self-cleaning, then contamination is reduced, but device complexity increases
Solution Approach 1:
The catalytic layer is applied selectively to specific regions of optical components that are outside the beam path. This localized application provides contamination protection exactly where needed without affecting the optical performance of beam-path components, achieving reliability improvement with minimal added complexity
4Productivity
If continuous operation is maintained to maximize throughput, then productivity is improved, but contamination accumulates on optical components
Solution Approach 1:
The catalytic cleaning action operates continuously throughout the lithography process without interruption. The catalytic layer constantly converts incoming hydrocarbon contaminants into volatile substances, maintaining optical component cleanliness throughout continuous operation and enabling sustained high throughput
Data Source
AI summary
A microlithographic optical system, wherein the optical system is designed for operation with electromagnetic radiation that passes through the optical system along a used beam path, and includes at least one component (105) having a region outside the used beam path, wherein this region has a catalytic or chemically active layer (110), and wherein the catalytic or chemically active layer (110) and/or a carrier (230, 240) bearing this layer (110) is porous.