Rotating Electrode Wheel Cooling for High Power EUV Sources
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Solution Overview
Problem
High power operation of gas discharge sources for EUV lithography results in overheating of electrode wheels due to insufficient heat dissipation, limiting their use in high volume manufacturing applications.
Innovation Solution
An electrode device with a rotatable electrode wheel covered by a design that forms a cooling channel and gap to manage the liquid metal film, allowing for efficient heat dissipation and minimizing film thickness, using a separate liquid material application unit to control the film's thickness and position, and incorporating wiper units to prevent droplet formation and erosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high electrical input powers are applied to achieve high volume manufacturing EUV source, then productivity is improved, but electrode wheels overheat due to insufficient heat dissipation
Solution Approach 1:
The electrode wheel is segmented into multiple cooling channels that distribute coolant flow across the electrode structure. This segmentation allows heat to be dissipated from multiple locations simultaneously, significantly improving heat dissipation capacity and enabling high power operation without overheating.
Solution Approach 2:
A liquid coolant circulation system is implemented with inlet and outlet channels to actively remove heat from the electrode wheel. The hydraulic flow of coolant through the cooling channels provides continuous heat dissipation, enabling the electrode to withstand high electrical input powers required for high volume manufacturing.
2Temperature
If electrode wheel rotation speed is increased to improve cooling and reduce debris, then heat dissipation is improved, but liquid metal film stability deteriorates
Solution Approach 1:
The system dynamically balances electrode rotation speed with liquid metal application rate to maintain film stability. The rotation speed is optimized to provide sufficient cooling while the liquid metal flow rate is adjusted to ensure continuous, stable film formation that can withstand centrifugal forces at high rotation speeds.
Solution Approach 2:
The liquid metal film thickness and stability are monitored and used to feedback control the application rate and rotation speed. This ensures the film remains stable during high-speed rotation while still providing effective cooling and protection.
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
Enables operation of gas discharge sources at high electrical powers without overheating, allowing for high volume manufacturing EUV sources with improved electrode cooling and stability, and increased rotational speeds, reducing debris and ensuring stable EUV output.
Implementation Method 1
The proposed cover is designed to form a cooling channel in said circumferential direction between the cover, the outer circumferential surface and a radially outer part of the side surfaces for cooling the electrode wheel by liquid material
Implementation Method 2
The liquid metal film also electrically connects the electrode wheels with a power supply which is connected to the electrically conductive connecting element. Furthermore, the liquid metal dissipates the heat introduced into the electrodes by the gas discharge
Data Source
AI summary
The present invention relates to an electrode device (1, 2) for gas discharge sources and to a gas discharge source having one or two of said electrode devices (1, 2). With the proposed design of the cover (8), an efficient cooling of the electrode wheel (7) is achieved, allowing high electrical powers for operating gas discharge sources with such an electrode device.