Mirror Device Shielding for EUV Plasma Ionization
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Solution Overview
Problem
In projection exposure apparatuses, especially EUV systems, the illumination radiation can cause ionization and plasma formation, leading to charged particles reaching sensitive components behind the mirrors, causing disturbances in mirror positioning and potential damage.
Innovation Solution
A mirror device with electrically conductive shielding elements is used to create an electric field adjacent to the mirror's side and rear surfaces, shielding sensitive components from charged particles by applying different electrical voltages to these elements, effectively preventing ionized particles from reaching protected volumes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If mirrors are used in EUV projection exposure apparatus, then reflection of EUV radiation is achieved, but ionization and plasma formation occur leading to charged particles reaching sensitive components
Solution Approach 1:
Electrically conductive shielding elements are introduced as intermediary components between the mirror and sensitive components. These shielding elements create an electric field that acts as a mediator to repel charged particles, preventing them from reaching the sensitive components while allowing the mirror to continue its EUV radiation reflection function
Solution Approach 2:
The harmful charged particles generated by ionization are deflected by the electric field created by the shielding elements. The harmful ionization effect is converted into a beneficial situation where the charged particles are systematically managed and redirected away from sensitive components through the electric field, turning a detrimental phenomenon into a controllable aspect of the system
2Reliability
If shielding elements are added to protect from charged particles, then reliability of mirror positioning is improved, but device complexity increases
Solution Approach 1:
The shielding elements are designed to serve multiple functions: they provide electrical shielding from charged particles, maintain the vacuum environment by conforming to the mirror structure, and can be integrated with existing mirror support structures. This multi-functionality reduces the need for separate protective mechanisms, thereby limiting the increase in device complexity
Solution Approach 2:
The shielding elements are positioned in the space between the mirror and the chamber wall, effectively nesting the shielding function within the existing structural hierarchy. This nesting approach allows the shielding elements to utilize available space without requiring additional external structures, thus minimizing the increase in overall device 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 electric field effectively shields sensitive components and improves the stability and precision of mirror positioning by preventing charged particles from reaching critical areas, ensuring reliable operation in rarefied or plasma environments.
Implementation Method 1
a mechanism for producing an electric field in a region adjacent to the at least one side surface and/or the rear side
Implementation Method 2
such an electric field can serve for shielding a predetermined volume from free charges
Data Source
AI summary
A mirror device includes at least one electrically conductive shielding element, which forms a mechanism for producing an electric field in a region adjacent to at least one side surface and/or a rear side of a mirror body.