Beam Delivery System for EUV Light Generation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In extreme ultraviolet (EUV) light generation systems, the focal point of a pulse laser beam can either hit the target, causing return beams to damage upstream optical elements or be set upstream, focusing the return beam and damaging the beam delivery system, leading to inefficiencies and potential damage to optical components.
Innovation Solution
A beam delivery system with multiple adjusters that control the divergence angle of the pulse laser beam, allowing for the adjustment of beam focus to a downstream position, preventing damage to optical elements by ensuring the return beam has a positive divergence angle, thus reducing energy density and minimizing damage risk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the focal point of the pulse laser beam is set to hit the target, then EUV light generation efficiency is improved, but return beams damage upstream optical elements
Solution Approach 1:
The patent converts the harmful return beam into a beneficial diagnostic tool. By positioning a beam monitor at the target to detect return beams, the system uses these previously harmful reflections to monitor plasma generation quality and adjust laser parameters accordingly, transforming a damage-causing element into a feedback mechanism for optimization
Solution Approach 2:
The patent introduces a beam monitor as an intermediary component between the target and upstream optical elements. This monitor detects return beams and provides information to the control system, enabling indirect monitoring of the interaction between laser and target without exposing upstream optics to direct damage from high-energy return beams
2Object-affected harmful factors
If the focal point is set upstream to avoid damage, then optical elements are protected, but the return beam becomes focused and damages the beam delivery system
Solution Approach 1:
The patent implements a feedback control system where the beam monitor detects return beams and sends signals to the control system. Based on this feedback, the control system adjusts laser parameters or focal point positioning in real-time to prevent focused return beams from damaging the beam delivery system, creating a closed-loop protection mechanism
Solution Approach 2:
The patent performs preliminary positioning of the focal point upstream of the target before the laser beam reaches it. This preliminary action prevents the formation of highly focused return beams that would otherwise travel back through the beam delivery system and cause damage, proactively eliminating the hazard before it can manifest
3Ease of operation
If multiple beam adjusters are used to control divergence angle, then beam focus control is improved, but system complexity increases
Solution Approach 1:
The patent divides the beam control function into multiple independent beam adjusters positioned at different locations in the beam path. Each adjuster handles a specific aspect of beam shaping or divergence control, allowing for modular adjustment and independent optimization of different beam parameters without interfering with each other
Solution Approach 2:
The patent designs beam adjusters that can perform multiple functions - controlling divergence angle, adjusting focal point position, and shaping beam profile. This multi-functionality reduces the need for separate dedicated components for each function, thereby managing system complexity while maintaining comprehensive beam control capability
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 system effectively prevents damage to optical elements by achieving a downstream defocused state, ensuring efficient EUV light generation while maintaining the integrity of the beam delivery system components.
Implementation Method 1
a Laser Produced Plasma (LPP) type system in which plasma is generated by irradiating a target material with a laser beam
Implementation Method 2
a plurality of beam adjusters configured to adjust a divergence angle of a pulse laser beam outputted from the laser apparatus
Implementation Method 3
a beam monitor configured to receive the sample beam and output a monitored diameter
Data Source
AI summary
A beam delivery system may include: beam adjusters configured to adjust a divergence angle of a pulse laser beam; a beam sampler configured to separate a part of the pulse laser beam outputted from a first beam adjuster provided at the most downstream among the beam adjusters to acquire a sample beam; a beam monitor configured to receive the sample beam and output a monitored diameter; and a beam delivery controller configured to control the beam adjusters based on the monitored diameter. The beam delivery controller may adjust each of beam adjusters other than the first beam adjuster selected one after another from the most upstream so that the monitored diameter at the beam monitor becomes a predetermined value specific to the beam adjuster, and adjust the first beam adjuster so that the pulse laser beam becomes focused at a position downstream of a target position.