EUV Plasma Debris Control via Real-Time Imaging Feedback
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Solution Overview
Problem
Lithographic apparatuses using EUV radiation face issues with debris generation from the plasma formation region, which can damage components and affect the generation and delivery of EUV radiation, due to the inability to effectively track and mitigate the unwanted particulate debris.
Innovation Solution
A radiation system that includes a fuel emitter, a first laser for generating a plasma, an imaging device to capture images of the plasma, and a controller to analyze these images and generate instructions to modify the operation of components to reduce debris, such as altering the laser-fuel interaction or adjusting the fuel properties, thereby minimizing debris generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If shadowgraph techniques are used to track fuel targets and debris, then debris can be detected, but the system requires powerful lasers and complex timing mechanisms increasing device complexity
Solution Approach 1:
The patent uses imaging devices to capture images of the plasma, which serve as a copy or representation of the plasma state. By analyzing these images, the system can determine plasma properties and infer debris characteristics without directly imaging the debris itself, thus avoiding the need for complex shadowgraph techniques
Solution Approach 2:
The patent replaces the mechanical/optical shadowgraph system (requiring powerful lasers and precise timing) with an imaging-based system that captures plasma images and uses computational analysis to infer debris properties. This substitution simplifies the hardware requirements while maintaining debris detection capability
2Productivity
If debris is generated from plasma formation, then EUV radiation can be produced, but debris damages components and reduces system reliability
Solution Approach 1:
The patent implements a feedback control system where imaging devices monitor plasma properties in real-time, the controller analyzes these images to determine debris characteristics, and then generates control signals to adjust laser or fuel emitter parameters. This closed-loop feedback enables dynamic optimization to maintain EUV production while minimizing debris generation and its damaging effects
Solution Approach 2:
The patent changes operational parameters such as laser power, pulse duration, fuel type, or fuel delivery conditions based on real-time plasma imaging analysis. By adjusting these parameters dynamically, the system optimizes the balance between EUV radiation generation and debris production, thereby maintaining reliability while preserving productivity
3Reliability
If real-time plasma imaging and control is implemented, then debris effects are reduced, but the device complexity increases
Solution Approach 1:
The imaging devices serve multiple functions: they capture plasma images for analysis, enable determination of plasma properties, provide feedback for control, and can potentially monitor multiple plasma parameters simultaneously. This multi-functionality reduces the need for separate dedicated systems for each function, thereby limiting the increase in overall device complexity while achieving real-time control
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
This approach allows for real-time control of the plasma generation process, reducing debris impact on components and improving the efficiency and reliability of EUV radiation production by using image analysis to adjust operational parameters, thus enhancing the system's performance and reducing maintenance needs.
Implementation Method 1
a first laser arranged to provide a first laser beam at the plasma formation region such that in use the first laser beam is incident on the fuel target to generate a radiation emitting plasma
Implementation Method 2
an imaging device arranged to obtain a first image of a radiation emitting plasma at the plasma formation region
Data Source
AI summary
A radiation system to generate a radiation emitting plasma, the radiation system include a fuel emitter to provide a fuel target at a plasma formation region, a first laser arranged to provide a first laser beam at the plasma formation region incident on the fuel target to generate a radiation emitting plasma, an imaging device arranged to obtain a first image of the radiation emitting plasma at the plasma formation region, the first image indicating at least one image property of the radiation emitting plasma, and a controller. The controller is arranged to receive the first image, and to generate at least one instruction based on the at least one image property of the radiation emitting plasma to modify operation of at least one component of the radiation system to reduce a detrimental effect of debris.