EUV Target Supply Control for Stable Droplet Coalescence
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Solution Overview
Problem
Existing EUV light sources face challenges in precisely tuning the characteristics of targets delivered to the target space, which affects the efficiency and consistency of EUV light production.
Innovation Solution
A target apparatus comprising a target generator, a sensor module, and a target generator controller, which detects aspects of the target material as it travels towards the target space, produces a one-dimensional signal, and modifies the target material's characteristics based on this analysis to optimize its trajectory and coalescence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If target material is released through a nozzle opening, then target material can be delivered to the target space, but the Rayleigh Plateau instability causes sub-targets to fail coalescence into stable targets
Solution Approach 1:
The patent applies preliminary action by detecting target material characteristics before the instability fully develops and modifying release parameters in advance. The sensor module monitors target material properties during flight, and the controller adjusts release parameters proactively to prevent coalescence failure, rather than waiting for the instability to manifest completely.
Solution Approach 2:
The patent implements feedback control by using the sensor module to detect aspects of target material in flight and providing this information to the controller, which then modifies release parameters based on the detected characteristics. This closed-loop feedback system continuously adjusts the release process to maintain stable target formation despite the Rayleigh Plateau instability.
2Productivity
If conventional target release methods are used, then target material can be supplied, but EUV light production efficiency is reduced due to target instability
Solution Approach 1:
The feedback principle is applied by continuously monitoring target material characteristics with the sensor module and using this information to adjust release parameters. This ensures that targets reaching the laser interaction zone have consistent properties, thereby maintaining high EUV light production efficiency while improving target reliability.
Solution Approach 2:
The patent applies parameter changes by dynamically modifying release parameters (such as pressure, temperature, or flow rate) based on real-time detection of target material characteristics. These parameter adjustments optimize target formation and stability, directly improving both EUV production efficiency and target consistency.
3Manufacturing precision
If no real-time detection is implemented, then the system is simpler, but target characteristics cannot be controlled during flight
Solution Approach 1:
The patent replaces complex mechanical detection and adjustment systems with optical or electromagnetic sensing methods. The sensor module uses non-contact detection to monitor target material characteristics, and the controller uses computational algorithms to determine parameter modifications, reducing mechanical complexity while maintaining precise control capability.
Solution Approach 2:
The patent focuses on changing key release parameters that have the greatest impact on target characteristics. By identifying and controlling only the most critical parameters rather than all possible variables, the system achieves precise target control with a relatively simple detection and control architecture.
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 apparatus enables precise control over the characteristics of the targets, ensuring they coalesce correctly and maintain desired shapes before reaching the target space, thereby enhancing the efficiency and consistency of EUV light production.
Implementation Method 1
The actuation apparatus can include a piezoelectric inducer configured to apply pressure to target material in the form of fluid in the reservoir
Implementation Method 2
The sensor module can include one or more photodiodes, the output of each is a voltage signal related to current produced from the detected light
Implementation Method 3
leading to instability and inefficiency in EUV light production due to the Rayleigh Plateau instability, which results in sub-targets failing to coalesce into desired targets
Data Source
AI summary
A target apparatus (300) for an extreme ultraviolet (EUV) light source includes a target generator, a sensor module (130), and a target generator controller (325). The target generator includes a reservoir (115) configured to contain target material (114) that produces EUV light in a plasma state and a nozzle structure (117) in fluid communication with the reservoir. The target generator defines an opening (119) in the nozzle structure through which the target material received from the reservoir is released. The sensor module is configured to: detect an aspect relating to target material released from the opening as the target material travels along a trajectory toward a target space (112), and produce a one-dimensional signal from the detected aspect. The target generator controller is in communication with the sensor module and the target generator, and is configured to modify characteristics of the target material based on an analysis of the one-dimensional signal.