Movable EUV Collector Mirrors for Droplet Contamination Control
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Solution Overview
Problem
Conventional EUV lithography light source systems face contamination issues due to droplets from the excitation source material condensing on and adhering to the collector's reflective optics, leading to reduced light-collecting efficiency.
Innovation Solution
A system with movable reflective mirrors that can be synchronized to switch between reflective and non-reflective states, where they are in a reflective state during EUV light emission and transition to a non-reflective state after emission to prevent droplet contamination, utilizing a time delay based on the speed and distance of droplet travel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the collector uses reflective mirrors to collect EUV light, then light-collecting efficiency is improved, but the mirrors become contaminated by droplets from the excitation source material
Solution Approach 1:
The patent applies the dynamics principle by making the mirrors movable rather than fixed. The mirrors can dynamically change their orientation between a light-collecting position (where they face the excitation source to maximize EUV light collection) and a protected position (where they are rotated away to prevent droplet contamination). This dynamic repositioning resolves the contradiction by allowing the system to optimize for light collection during operation and protect from contamination between operations.
Solution Approach 2:
The patent implements periodic action through the cyclic movement of mirrors between two states: during EUV light generation, mirrors are positioned to collect light; between generations, mirrors are repositioned to avoid droplet exposure. This periodic switching between functional states allows the system to maintain high light-collecting efficiency while periodically protecting the mirrors from contamination, thus resolving the technical contradiction.
2Reliability
If the mirrors are positioned to collect maximum EUV light, then light-collecting efficiency is improved, but droplets can reach and contaminate the mirrors
Solution Approach 1:
The movable mirror system allows dynamic adjustment of mirror position based on operational requirements. During EUV light generation, mirrors are positioned optimally for light collection; between operations, they are repositioned to protected orientations. This dynamic capability enables the system to maintain reliability for light collection while preventing substance loss through contamination.
Solution Approach 2:
The system performs preliminary action by repositioning the mirrors to a protected state before droplets can reach them. The timing control system ensures that mirrors are moved out of the droplet trajectory path in advance, preventing contamination before it occurs. This preliminary protective action resolves the contradiction by proactively preventing mirror contamination while maintaining light-collecting efficiency during operational phases.
3Device complexity
If conventional fixed mirrors are used, then the system structure is simple, but light-collecting efficiency decreases quickly due to contamination
Solution Approach 1:
The patent introduces dynamic elements (movable mirrors with rotation mechanisms) to resolve the contradiction between structural simplicity and sustained productivity. While the added mechanical components increase device complexity, they enable the mirrors to be repositioned periodically to avoid contamination, thereby maintaining high light-collecting efficiency over extended operational periods. The system trades initial structural simplicity for long-term productivity preservation.
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
Effectively prevents contamination of reflective mirrors, maintaining light-collecting efficiency and reducing maintenance costs by ensuring the mirrors remain clean and functional.
Implementation Method 1
The laser radiation can generate droplets from the EUV light excitation source material
Implementation Method 2
a plurality of reflective mirrors surrounding the EUV light excitation source material... in a reflective state for reflecting the EUV light
Implementation Method 3
the source material vapor droplets may condense on the EUV light-collecting optical elements
Data Source
AI summary
Various embodiments provide systems and methods for extreme ultraviolet (EUV) lithography light source. An exemplary system can include a laser radiation apparatus configured to provide laser radiation. The system can further include an EUV light excitation source material configured to receive the laser radiation to generate an EUV light. The laser radiation can generate droplets from the EUV light excitation source material. The system can further include a collector configured to collect the EUV light. The collector can include a plurality of reflective mirrors surrounding the EUV light excitation source material. The plurality of reflective mirrors can be movable. The collector can further include a mirror control system synchronized with the laser radiation apparatus and configured to set the plurality of reflective mirrors to be in one of a reflective state for reflecting the EUV light and a non-reflective state for preventing contamination by the droplets.