EUV Optic Assembly Thermal Control via Coolant Heat Transfer
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Solution Overview
Problem
Existing EUV lithography systems face challenges with heat load in optic assemblies due to high-power lasers, leading to decreased conversion efficiency and stability, and increased debris contamination on EUV collectors.
Innovation Solution
A cooling module is implemented to regulate the temperature of optic assemblies in the beam transport module by detecting real-time coolant temperature data and adjusting the heat transfer rate, ensuring accurate targeting of laser pulses on droplets and minimizing thermal deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If high-power laser beams are used to generate EUV light, then EUV light intensity is improved, but heat load on optic assemblies increases causing thermal deformation and decreased stability
Solution Approach 1:
A coolant is introduced as an intermediary substance between the heat-generating optic assemblies and the environment. The coolant circulates through channels in the optic assemblies, absorbing excess heat and preventing thermal deformation, thereby enabling high-power laser operation without compromising optical stability
Solution Approach 2:
A hydraulic cooling system is implemented where coolant flows through controlled channels within the optic assemblies. The hydraulic flow rate and pressure are regulated to optimize heat removal efficiency, maintaining optimal operating temperatures despite high laser power input
2Power
If high-power laser beams are focused on droplet targets, then EUV light emission is improved, but debris contamination on EUV collectors increases
Solution Approach 1:
The droplet target is pre-formed and positioned with precise control before laser irradiation. This preliminary preparation ensures optimal laser-droplet interaction, maximizing EUV emission while minimizing debris generation through controlled ablation conditions
Solution Approach 2:
Laser parameters such as pulse duration, intensity, and focal position are optimized to achieve the threshold for efficient EUV generation without excessive energy that would cause debris formation. The droplet size and composition are also adjusted to match the laser parameters for clean energy conversion
3Stability of the object's composition
If cooling is applied to optic assemblies, then thermal stability is improved, but system complexity increases due to additional cooling components
Solution Approach 1:
The cooling channels are integrated directly into the optic assembly structure, merging the optical and thermal management functions into a single component. This eliminates separate cooling hardware and reduces overall system complexity while maintaining effective thermal control
Solution Approach 2:
The optic assemblies are designed to serve multiple functions: optical reflection/focusing and heat dissipation. The same structural components that form the optical paths also contain the cooling channels, making the system more compact and less complex
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 enhances EUV plasma quality, reduces debris on EUV collectors, and improves energy conversion efficiency and stability, increasing the availability of the lithography system by 3%.
Implementation Method 1
adjusting a heat transfer rate between the coolant and the first optic assembly
Implementation Method 2
exciting the droplet of the target material into plasma with the main pulse laser
Data Source
AI summary
In accordance with some embodiments, a lithography method in semiconductor manufacturing is provided. The lithography method includes transmitting a main pulse laser to a zone of excitation through a first optic assembly. The lithography method further includes supplying a coolant to the first optic assembly and detecting a temperature of the coolant with a use of at least one sensor. The lithography method also includes adjusting a heat transfer rate between the coolant and the first optic assembly based on the temperature of the first optic assembly. In addition, the lithography method includes generating a droplet of a target material into the zone of excitation. The lithography method further includes exciting the droplet of the target material into plasma with the main pulse laser in the zone of excitation.