EUV Droplet Generator Temperature Control for Refill Speed
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Solution Overview
Problem
The existing EUV lithography systems face challenges with the degradation of the EUV radiation source collector due to debris accumulation, leading to reduced reflectivity and a shorter usable lifetime, as well as long refill and maintenance processes that increase contamination and oxidation risks.
Innovation Solution
A droplet generator assembly with an advanced temperature control system that includes passive and active heat dissipation devices, such as a heat sink and fan, to rapidly cool and heat the droplet generator, reducing the time required for refill and maintenance processes, and a gas or liquid-based active temperature control system to manage temperature and prevent oxidation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the EUV radiation source collector is used continuously, then productivity is improved, but the collector degrades due to debris accumulation, reducing reflectivity and shortening usable lifetime
Solution Approach 1:
The patent extracts the target droplet generator from the main vacuum chamber, allowing it to be refilled and maintained outside the chamber. This separation enables the collector to operate continuously without being interrupted by refill operations, while the generator can be maintained separately without affecting collector reflectivity.
Solution Approach 2:
The patent implements preliminary cooling of the target droplet generator before refill operations. By cooling the generator in advance, the system prepares for maintenance without interrupting collector operation, allowing quick replacement of depleted targets while maintaining collector performance.
2Reliability
If the refill and maintenance processes are performed frequently, then reliability is improved, but the time required for these processes increases, reducing productivity
Solution Approach 1:
The patent implements preliminary cooling of the target droplet generator before refill operations. By cooling the generator in advance to below the melting point of the target material, the system prepares for quick refill without requiring extended downtime, thus maintaining high productivity while ensuring reliable target droplet formation.
Solution Approach 2:
The patent enables rapid cooling and refill operations by moving the generator outside the vacuum chamber. This allows the system to quickly complete maintenance tasks and return to operation, minimizing interruption time and maintaining high productivity despite frequent refills.
3Manufacturing precision
If the target material is kept at high temperature to prevent solidification, then manufacturing precision is improved, but oxidation and contamination risks increase
Solution Approach 1:
The patent maintains the target material in an inert or reduced pressure environment within the generator. This allows the target to be heated to temperatures above its melting point for optimal droplet formation while preventing oxidation and contamination through the protective atmosphere.
Solution Approach 2:
The patent separates the target material storage and heating zone from the droplet generation zone. The target material is stored and heated in a protected environment, then transferred to the droplet generation area where it is atomized by the laser, minimizing exposure to oxidizing conditions while maintaining manufacturing precision.
4Productivity
If the laser power is increased to improve EUV radiation output, then productivity is improved, but heat generation increases, requiring more complex temperature control
Solution Approach 1:
The patent divides the temperature control into separate zones: one for the target material reservoir and one for the droplet generation area. This segmented approach allows independent optimization of each zone's temperature control, managing heat from high-power lasers while maintaining simple, effective thermal management.
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 solution significantly reduces the time for refill and maintenance processes, minimizing contamination and oxidation, thereby increasing yield and maintaining the stability of target droplets for high-repetition operations and extending the usable lifetime of the EUV radiation source components.
Implementation Method 1
The temperature control system includes passive and active heat dissipation devices, such as a heat sink and fan, to rapidly cool and heat the droplet generator
Implementation Method 2
The droplet generator includes heating elements for heating the target material in the reservoir above a melting point of the target material for generating the liquid droplets
Implementation Method 3
impinging a laser onto the target droplet for producing extreme violet light
Data Source
AI summary
A droplet generator assembly includes a storage tank, a refill system, a droplet generator, and a temperature control system. The storage tank is configured to store a target material. The refill system is connected to the storage tank. The droplet generator includes a reservoir and a nozzle connected to the reservoir, in which the droplet generator is connected to the refill system, and the refill system is configured to deliver the target material to the reservoir. The temperature control system is adjacent to the refill system or the reservoir.