EUV Collector Mirror Debris Mitigation via Transverse Gas Flow
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Solution Overview
Problem
The collector mirror in lithographic apparatuses degrades and deforms when producing extreme ultraviolet radiation due to debris from the plasma, which existing buffer gases fail to adequately mitigate.
Innovation Solution
A module that includes a supply of ignition material, a laser to create a plasma, a collector mirror to focus the radiation, and a fluid supply to generate a gas flow transverse to the mirror surface, mitigating particle debris using the Péclet effect, and optionally a heat sink to divert thermal energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a collector mirror is used to focus extreme ultraviolet radiation, then the radiation can be focused effectively, but the mirror degrades and deforms due to particle debris from the plasma
Solution Approach 1:
A buffer gas (such as hydrogen or helium) is introduced as an intermediary substance between the plasma and the collector mirror. This buffer gas absorbs and mitigates the particle debris generated by the plasma, preventing direct contact with the mirror surface while maintaining the mirror's radiation focusing function
Solution Approach 2:
A gas flow system is implemented to dynamically manage the buffer gas environment around the collector mirror. The gas flow is controlled to flow away from the mirror surface in a direction transverse to the mirror surface, actively removing particle debris and thermal energy while preserving the mirror's optical performance
2Reliability
If buffer gas is used to mitigate particle debris, then some protection is provided, but the mirror still degrades and deforms
Solution Approach 1:
The buffer gas is not merely present but actively flowed through the system. The gas flow is directed to flow away from the mirror surface transversely, creating a dynamic protective environment that continuously removes particle debris and thermal energy, significantly enhancing protection compared to static buffer gas
Solution Approach 2:
The state of the buffer gas is optimized by controlling its flow parameters (flow rate, direction, velocity). The gas flow is specifically configured to flow away from the mirror surface in a direction transverse to the surface, creating optimal conditions for debris removal while minimizing interference with radiation focusing
3Reliability
If gas flow is directed transverse to the mirror surface, then particle debris is effectively removed, but system complexity increases
Solution Approach 1:
The buffer gas flow system serves multiple functions simultaneously: it mitigates particle debris, removes thermal energy, and maintains a clean environment around the mirror. This multi-functionality reduces the need for separate systems for each protective function, thereby limiting the increase in overall system 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
Prevents deformation and degradation of the collector mirror by effectively removing particle debris and thermal energy, ensuring the longevity and performance of the mirror.
Implementation Method 1
a laser arranged to be focused on the predetermined target ignition position and to produce a plasma by hitting the droplet when it is located at the predetermined target ignition position
Implementation Method 2
produce a plasma by hitting the droplet... to change the droplet into an extreme ultraviolet producing plasma
Implementation Method 3
a collector mirror having a mirror surface constructed and arranged to reflect the radiation in order to focus the radiation in a focal point
Implementation Method 4
a fluid supply constructed to form a gas flow flowing away from the mirror surface in a direction transverse with respect to the mirror surface in order to mitigate particle debris produced by the plasma
Implementation Method 5
mitigate particle debris produced by the plasma... using the Péclet effect
Implementation Method 6
a heat sink to divert thermal energy away from the target ignition position
Data Source
AI summary
A module for producing extreme ultraviolet radiation, including an extreme ultraviolet radiation-emitting source, the source being provided with a supply configured to supply a fluid of an ignition material to a predetermined target ignition position and a target-igniting mechanism constructed and arranged to produce a plasma from the ignition material at the target ignition position, the plasma emitting the extreme ultraviolet radiation; a collector mirror constructed and arranged to focus radiation emitted by the plasma at a focal point; and a heat sink having a thermal energy-diverting surface constructed and arranged to divert thermal energy away from the target ignition position, wherein the heat sink is located at a position proximate the target ignition position.