EUV Reflective Optical Element Thermal Deformation Control

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Solution Overview

Problem

Lithographic apparatuses using extreme ultraviolet (EUV) radiation face challenges in efficiently directing and shaping EUV radiation beams due to thermal management issues and the need for precise control over reflective optical elements to minimize aberrations and maintain beam quality.

Innovation Solution

A system incorporating a reflective optical element with a thermal conditioning mechanism that includes cooling channels and thermo-electric devices to manage heat generated by the radiation beam, allowing for thermally induced deformation of the reflective surface to control its shape and aberrations, thereby optimizing the EUV beam's direction and quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a reflective optical element is used to direct EUV radiation beam, then the beam direction and quality can be controlled, but thermal loads cause deformation and aberrations that degrade performance

Engineering Contradiction:

Improvebeam qualityVSAvoidthermal load

Core Design Contradiction:

Manufacturing precisionVSTemperature

Solution Approach 1:

The patent applies parameter changes by using thermal conditioning mechanisms to actively control the temperature and shape of the reflective optical element. The system changes the physical state parameters (temperature, shape) of the optical element to compensate for thermal deformation, thereby maintaining beam quality despite thermal loads.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent addresses thermal expansion effects by using thermal conditioning mechanisms that can induce controlled thermal deformation in the reflective optical element. The system compensates for unwanted thermal expansion by applying controlled thermal fields to maintain the desired shape and optical performance.

Inventive Principle:

Principle #37Thermal expansion

2Manufacturing precision

If thermal conditioning mechanisms are added to control reflective surface shape, then beam quality can be maintained under thermal load, but device complexity increases

Engineering Contradiction:

Improvebeam qualityVSAvoidsystem complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies universality by designing thermal conditioning mechanisms that can perform multiple functions: they can heat, cool, and shape the reflective optical element using a single integrated system. The thermal conditioning mechanisms serve both to manage thermal loads and to control the shape of the reflective surface, reducing the need for separate systems.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges the thermal management function with the shape control function into a single thermal conditioning mechanism. By combining these functions, the system reduces overall complexity compared to having separate thermal management and shape control systems.

Inventive Principle:

Principle #5Merging (Combining)

3Temperature

If cooling channels are used to transport heat away from the body, then thermal load can be managed, but device complexity and manufacturing difficulty increase

Engineering Contradiction:

Improveheat dissipationVSAvoidmanufacturing complexity

Core Design Contradiction:

TemperatureVSEase of manufacture

Solution Approach 1:

The patent applies pneumatics and hydraulics by using cooling channels that transport heat away from the reflective optical element through fluid flow. The thermal conditioning mechanisms utilize fluid-based heat transfer to efficiently manage thermal loads, with channels designed to maximize heat dissipation while considering manufacturing constraints.

Inventive Principle:

Principle #29Pneumatics and hydraulics

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 manages thermal loads and controls the reflective surface's shape, enhancing the precision and quality of EUV radiation beams, enabling the formation of smaller features on substrates and improving the overall performance of lithographic processes.

Implementation Method 1

heat generated by partial absorption of the radiation beam by the reflective optical element

Methodology Applied

Scientific EffectHeat conduction: Conduction (thermal)

Implementation Method 2

transport away from the body, heat generated by partial absorption

Methodology Applied

Scientific EffectConvection: Convection

Implementation Method 3

control a shape of the reflective surface via thermally inducing a deformation of the body

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS11237491B2Reflective optical element for a radiation beam

Publication Date: 2022.02.01 ASML NETHERLANDS BV

AI summary

A system comprises a reflective optical element with a reflective surface that is configured to reflect a radiation beam. The reflective optical element also has a body. The system includes a thermal conditioning mechanism operative to thermally induce a deformation of the body under control of a controller. By means of controllably deforming the body, the shape of the reflective surface can be adjusted in a controlled manner.