Mini-Reactor Hydrogen Radical Cleaning for EUV Sensor Surfaces
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Solution Overview
Problem
Lithographic apparatuses using extreme ultraviolet (EUV) radiation sources face challenges with the deposition of tin and carbonaceous materials on mirrors, leading to reduced transmission and mirror degradation, which existing cleaning methods only partially address.
Innovation Solution
A lithographic apparatus equipped with a mini-reactor that generates hydrogen radicals to create a local environment for treating the sensing surfaces of internal sensors, effectively removing carbon-containing deposits without affecting other components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If EUV radiation sources are used to image smaller features, then manufacturing precision is improved, but mirrors and optical elements suffer from particle bombardment and debris deposition leading to reduced transmission and shortened lifespan
Solution Approach 1:
The patent converts the harmful effect of particle bombardment and debris deposition into a beneficial cleaning process. By introducing a contaminant barrier that generates hydrogen radicals, the previously harmful particles and deposited debris are transformed into removable contaminants that can be cleaned from optical surfaces, thereby extending mirror lifespan while maintaining EUV imaging capability
Solution Approach 2:
The patent introduces a contaminant barrier as an intermediary component between the plasma source and optical elements. This barrier serves as a mediator that intercepts harmful particles and debris, preventing direct damage to mirrors while allowing EUV radiation to pass through for imaging, thus resolving the contradiction between achieving small feature imaging and maintaining optical element reliability
2Duration of action of stationary object
If contaminant barriers are used to prevent debris deposition, then mirror lifespan is extended, but some debris still deposits on optical elements reducing transmission
Solution Approach 1:
The patent implements a self-service cleaning mechanism where the contaminant barrier itself generates hydrogen radicals that actively clean deposited debris from optical surfaces. The system automatically removes contaminants without requiring external intervention, maintaining transmission efficiency while the barrier continues to protect mirrors, thus resolving the contradiction between extending mirror lifespan and maintaining energy transmission
Solution Approach 2:
The patent changes the chemical environment by introducing hydrogen radicals that react with carbonaceous debris to form volatile compounds. This parameter change in the chemical state of deposited contaminants enables their removal through desorption and evacuation, thereby maintaining optical transmission while the contaminant barrier extends mirror lifespan
3Loss of energy
If hydrogen radical cleaning is applied to remove carbonaceous deposits, then transmission is restored, but the cleaning process must be localized to avoid affecting other components
Solution Approach 1:
The patent applies hydrogen radical cleaning locally at the contaminant barrier location rather than throughout the entire optical system. The contaminant barrier generates hydrogen radicals in a localized zone where carbonaceous deposits accumulate, enabling targeted cleaning of affected surfaces without exposing other components to the cleaning process, thus restoring transmission while managing system complexity
Solution Approach 2:
The patent segments the cleaning function from the main optical path by implementing it at the contaminant barrier location. The hydrogen radical generation and cleaning action are separated into a distinct functional zone, allowing independent optimization of the cleaning process without complicating the overall optical system design, thereby restoring transmission with controlled complexity
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 method effectively cleans sensing surfaces of internal sensors, maintaining mirror performance and preventing debris deposition, thereby extending the lifespan of optical elements.
Implementation Method 1
The mini-reactor is arranged to create, during use of the mini-reactor in a method for treating the sensing surface of the sensor, a local mini-environment comprising hydrogen radicals
Implementation Method 2
effectively removing carbon-containing deposits without affecting other components
Data Source
AI summary
A lithographic apparatus includes a projection system constructed and arranged to project a beam of radiation onto a target portion of a substrate, an internal sensor having a sensing surface, and a mini-reactor movable with respect to the sensor. The mini-reactor includes an inlet for a hydrogen containing gas, a hydrogen radical generator, and an outlet for a hydrogen radical containing gas. The mini-reactor is constructed and arranged to create a local mini-environment comprising hydrogen radicals to treat the sensing surface.