Dual Heat Shield Thermal Management for EUV Lithography
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Solution Overview
Problem
Microlithographic projection exposure apparatuses face challenges in protecting temperature-sensitive components from undesired heat input, leading to impaired imaging properties due to thermal fluctuations, especially in the EUV range where suitable light-transmissive refractive materials are scarce.
Innovation Solution
The implementation of a dual heat shield system, where a first heat shield absorbs heat from heat-emitting subsystems and is in mechanical contact with a cooling device, and a second heat shield further absorbs residual heat from the first, also in contact with a cooling device, significantly reducing temperature fluctuations and ensuring effective heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a single heat shield is used to absorb heat from mirrors, then heat absorption is improved, but residual heat still reaches temperature-sensitive components
Solution Approach 1:
The heat shield is divided into multiple segments (first heat shield and second heat shield) arranged in sequence. The first heat shield absorbs heat from mirrors, while the second heat shield absorbs residual heat from the first heat shield, creating a staged heat absorption system that progressively reduces thermal load on temperature-sensitive components.
Solution Approach 2:
The first heat shield acts as an intermediary between the mirrors and the second heat shield, absorbing initial heat load and transferring it to cooling devices. The second heat shield then serves as an intermediary to capture any remaining heat from the first heat shield, ensuring comprehensive thermal protection.
2Object-affected harmful factors
If heat shields are placed close to mirrors for effective heat absorption, then heat shielding efficiency is improved, but the heat shields themselves become overheated
Solution Approach 1:
The heat absorption function is segmented across two heat shields positioned at different locations. The first heat shield is positioned closer to mirrors for efficient heat capture, while the second heat shield is positioned further away to handle residual heat, distributing thermal load across multiple components.
Solution Approach 2:
Mechanical cooling devices are introduced to actively remove heat from the heat shields. These cooling devices replace passive thermal management with active cooling systems, enabling the heat shields to operate at higher temperatures without compromising the temperature stability of protected components.
3Reliability
If multiple heat shields are added to improve heat absorption, then temperature stability is improved, but device complexity increases
Solution Approach 1:
The heat shield system is segmented into functional units (first and second heat shields with respective cooling devices) that can be independently designed, manufactured, and maintained. This modular segmentation allows for systematic complexity management while achieving superior temperature stability.
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 configuration reduces heat transfer to temperature-sensitive components by approximately one order of magnitude, maintaining permissible temperature fluctuations below 500 μK/min, thereby protecting the imaging beam path and preventing excessive heating of mirrors, which could impair coatings.
Implementation Method 1
a first heat shield arranged such that it at least partly absorbs the heat emitted by the heat-emitting subsystem
Implementation Method 2
a first cooling device in mechanical contact with the first heat shield and designed to dissipate heat from the first heat shield
Implementation Method 3
a second heat shield which at least partly absorbs heat emitted by the first heat shield
Data Source
AI summary
An optical arrangement in an optical system, such as a microlithographic projection exposure apparatus, includes: at least one heat-emitting subsystem which emits heat during the operation of the optical system; a first heat shield which is arranged such that it at least partly absorbs the heat emitted by the heat-emitting subsystem; a first cooling device which is in mechanical contact with the first heat shield and is designed to dissipate heat from the first heat shield; and a second heat shield which at least partly absorbs heat emitted by the first heat shield. The second heat shield is in mechanical contact with a cooling device that dissipates heat from the second heat shield.