EUV Target Trajectory Metrology via Diagnostic Plasma
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Solution Overview
Problem
In laser produced plasma extreme ultraviolet light sources, existing methods struggle to accurately measure and adjust the trajectory of targets in real-time, leading to inefficiencies in EUV light production and contamination within the chamber due to plasma pushback forces and trajectory deviations.
Innovation Solution
A system and method that involves forming a diagnostic plasma, releasing a target along a trajectory, and using diagnostic light beams to determine moving properties such as speed and direction, allowing for adjustments to the radiation pulse's timing and direction to optimize target interaction and EUV light production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If real-time measurement and adjustment of target trajectory is implemented, then EUV light production efficiency is improved, but device complexity increases
Solution Approach 1:
The system performs preliminary measurement of target trajectory using diagnostic light beams before the main radiation pulse interacts with the target. This allows advance detection of trajectory deviations and enables pre-adjustment of the radiation pulse timing and direction, ensuring optimal interaction conditions are established beforehand rather than reacting to deviations after they occur
Solution Approach 2:
The system implements a closed-loop feedback mechanism where diagnostic light beams continuously measure target position and velocity, the control system processes this information to detect trajectory deviations, and adjustments are made to subsequent radiation pulses based on measured deviations. This real-time feedback ensures continuous optimization of EUV light production while maintaining manageable system complexity through automated control
2Measurement precision
If diagnostic light beams are used to measure target properties, then measurement precision is improved, but device complexity increases
Solution Approach 1:
Diagnostic light beams serve as an intermediary measurement tool that indirectly probes target properties without requiring direct contact or complex embedded sensors. The light beams interact with the target to provide information about position and velocity, enabling precise measurement while keeping the diagnostic system separate from and less complex than the main radiation pulse system
Solution Approach 2:
The system replaces complex mechanical measurement devices with optical measurement using light beams. This substitution enables non-contact, high-precision measurement of target trajectory and properties while reducing mechanical complexity, as optical systems can achieve fine measurement resolution without the wear, friction, and mechanical complexity of physical sensors
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 enables precise measurement and adjustment of target properties, enhancing EUV light production efficiency and reducing chamber contamination by aligning radiation pulses with moving targets, thus improving the overall performance of the EUV light source.
Implementation Method 1
detecting a first interaction between a first diagnostic light beam and the current target at a first location within the extended target region
Implementation Method 2
detecting a second interaction between a second diagnostic light beam and the current target at a second location within the extended target region
Implementation Method 3
irradiating a target material, for example, in the form of a droplet, plate, tape, stream, or cluster of material, with an amplified light beam that can be referred to as a drive laser
Implementation Method 4
converting a material that has an element, for example, xenon, lithium, or tin, with an emission line in the EUV range in a plasma state
Implementation Method 5
the plasma is typically produced in a sealed vessel, for example, a vacuum chamber, and monitored using various types of metrology equipment
Data Source
AI summary
A method is described for measuring a moving property of a target. The method includes: forming a remaining plasma that at least partially coincides with an extended target region, the remaining plasma being a plasma formed from an interaction between a prior target and a prior radiation pulse in a target space; releasing a current target along a trajectory toward the target space that is at least partly overlapping the extended target region; determining one or more moving properties of the current target when the current target is within the extended target region and after a prior and adjacent target has interacted with a prior radiation pulse in the target space; and if any of the determined one or more moving properties of the current target are outside an acceptable range, then adjusting one or more characteristics of a radiation pulse directed toward the target space.