EUV Plasma Source Cooling Circuit with Atomizing Secondary Loop
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Solution Overview
Problem
Plasma-based radiation sources face challenges in maintaining a constant metal coolant temperature under varying heat inputs, from standby to continuous operation, due to inefficient cooling systems that fail to compensate for sharply fluctuating heat injections.
Innovation Solution
A secondary cooling circuit with a liquid coolant that evaporates at the metal coolant's operating temperature, combined with an atomizing arrangement and control unit to adjust cooling output through individual nozzle control, ensures the metal coolant's temperature remains virtually constant by selectively spraying cooling liquid on defined wall regions of the primary cooling circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a primary cooling circuit with metal coolant circulation is used, then the revolving element can be cooled during operation, but the temperature of the metal coolant cannot be maintained constant under sharply varying heat inputs from standby to continuous operation
Solution Approach 1:
The cooling system is divided into two separate circuits: a primary cooling circuit with metal coolant for continuous cooling and a secondary cooling circuit with spray cooling for rapid temperature correction. This segmentation allows each circuit to specialize in different cooling scenarios, with the secondary circuit providing adaptive response to varying heat inputs while the primary circuit maintains baseline cooling.
Solution Approach 2:
A control unit acts as an intermediary between the temperature sensing system and the cooling circuits. It receives temperature signals from sensors in the primary cooling circuit and automatically activates or deactivates the secondary cooling circuit accordingly, enabling automatic adaptation to varying heat inputs without manual intervention.
2Speed
If spray cooling is applied to rapidly cool the metal coolant, then temperature can be corrected quickly, but the cooling output must be deactivated during pauses to prevent solidification of the metal coolant
Solution Approach 1:
The secondary cooling circuit is designed to be dynamically controllable, allowing rapid activation during high heat input periods and complete deactivation during pauses. This dynamic control enables the system to provide aggressive cooling when needed while preventing over-cooling that would cause solidification, adapting the cooling intensity to real-time operational conditions.
Solution Approach 2:
Temperature sensors continuously monitor the metal coolant temperature and provide feedback to the control unit. Based on this feedback, the control unit automatically adjusts the secondary cooling circuit operation, activating it when temperature rises above the minimum operating temperature and deactivating it when temperature approaches the solidification point, ensuring reliable operation across all conditions.
3Adaptability or versatility
If multiple cooling nozzles are provided for differentiated cooling, then selective cooling of defined wall regions is possible, but the device complexity increases
Solution Approach 1:
The atomizing arrangement is designed with multiple cooling nozzles positioned to target specific wall regions of the primary cooling circuit vessel. Each nozzle or group of nozzles can be independently controlled to provide localized cooling where heat input is highest, such as near the revolving element immersion zone, while leaving other regions with minimal cooling. This local quality approach enables adaptive cooling distribution without requiring complete system complexity.
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 solution effectively maintains a stable metal coolant temperature across varying operational conditions, preventing solidification and ensuring continuous efficient cooling of plasma-based radiation sources.
Implementation Method 1
a liquid coolant (4) that evaporates at the operating temperature of the metal coolant (3)
Implementation Method 2
at least one atomizing arrangement (41) for the cooling liquid (4) which is arranged in such a way that a defined wall region (231, 232, 233...) of the at least one cooling section (21) of the first vessel (2) can be sprayed with the cooling liquid (4)
Implementation Method 3
a cooling unit (7) for the cooling liquid (4) which is provided for sucking evaporated cooling liquid out of the at least one second vessel (5), for condensing and for returning the cooling liquid under pressure to the at least one atomizing arrangement (41)
Data Source
AI summary
An arrangements and methods for cooling a plasma-based radiation source having a revolving element which is to be cooled, particularly for application in EUV radiation sources, is disclosed. The revolving element is immersed in the metal coolant in a first vessel of a primary cooling circuit, and a secondary cooling circuit with a cooling liquid evaporating at the desired operating temperature of the metal coolant has a control unit for controlling at least one atomizing arrangement in a differentiated manner and for selectively controlling a heater in case the determined temperature falls below a minimum operating temperature of the metal coolant. The at least one atomizing arrangement in a cooling section selectively sprays individual wall regions of the first vessel with the cooling liquid depending on the determined temperature of the metal coolant.