Lithography Mirror Optical Bonding With Gas-Venting Channels

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Solution Overview

Problem

The challenge in producing mirrors for lithography systems is the precise and reproducible connection of multiple mirror parts while minimizing gas inclusions that can cause deformation and interferometric measurement issues, which are exacerbated by heating and temperature changes.

Innovation Solution

The method involves optically contact bonding two mirror parts using Van der Waals forces, with controlled alignment and venting through cooling channel openings to prevent gas inclusions, and using auxiliary channels for additional venting and pressure equalization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If multiple mirror parts are connected to form a cooled mirror, then cooling capability is improved, but gas inclusions may be enclosed between the parts causing deformation and measurement issues

Engineering Contradiction:
Improvecooling capabilityVSAvoidconnection precision
Core Design Contradiction:
TemperatureVSManufacturing precision

Solution Approach 1:

The mirror is divided into multiple mirror parts (first mirror part and second mirror part) that can be separately cooled. Each part has its own cooling channels, allowing independent temperature control while maintaining optical functionality. This segmentation enables improved cooling capability without requiring a single large monolithic structure.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A connecting element is introduced as an intermediary between the first and second mirror parts. This connecting element facilitates precise alignment and connection while providing a pathway for venting gas during the bonding process. The intermediary structure resolves the contradiction by enabling both tight connection for precision and gas escape paths to prevent inclusions.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Strength

If mirror parts are bonded together tightly, then connection strength is improved, but gas inclusions are more likely to be trapped

Engineering Contradiction:
Improveconnection strengthVSAvoidgas inclusions
Core Design Contradiction:
StrengthVSObject-generated harmful factors

Solution Approach 1:

The connecting element is designed in advance with integrated venting functionality. Before the bonding process completes, the venting channels provide escape routes for gas. This preliminary design of the connection structure with built-in gas management prevents gas inclusions from forming during the bonding process, allowing strong connections without trapped gas.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The venting channels in the connecting element, which might seem to weaken the connection structure, actually convert the harmful effect of gas pressure into a beneficial feature. By providing controlled pathways for gas escape, the venting channels prevent gas inclusions that would otherwise compromise the connection strength and optical performance.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

3Temperature

If cooling channels are added to mirror parts, then thermal management is improved, but device complexity increases

Engineering Contradiction:
Improvethermal managementVSAvoidstructure complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The connecting element serves multiple functions simultaneously: it mechanically joins the mirror parts, provides alignment references, and incorporates venting channels for gas management. This multi-functionality reduces the need for separate components, thereby limiting the increase in device complexity while achieving effective thermal management through the cooling channels in each mirror part.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 approach simplifies the production of mirrors with high precision and reproducibility, reducing the risk of gas inclusions and deformation, ensuring accurate light deflection and imaging performance.

Implementation Method 1

the first mirror part and the second mirror part are optically contact bonded to one another, that is to say are connected to one another due to Van der Waals forces

Methodology Applied
Scientific EffectVan der Waals forces: Van der Waals Force

Implementation Method 2

at least one mirror, which deflects the light in a specified way by reflection at its optical surface

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 3

a plurality of cooling channels (18) which are formed as open towards the second connecting surface (16) of the upper part (14)

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 4

Cooling channels are formed between a first mirror part and a second mirror part

Methodology Applied
Scientific EffectConvection: Convection

Data Source

PatentEP4320484B1Method for producing a mirror for a lithography system
Publication Date: 2025.11.05 CARL ZEISS SMT GMBH
  • EP4320484B1 patent drawingFigure 1
  • EP4320484B1 patent drawingFigure 2
  • EP4320484B1 patent drawingFigure 3~5

AI summary

The invention relates to a method for producing a mirror (12) of a lithography system. In the method according to the invention, a first mirror part (13) and a second mirror part (14) are provided, wherein cooling channels (18) having elongate cooling channel openings (19) in the region of a first connecting surface (15) of the first mirror part (13) are formed in the first mirror part (13) and/or cooling channels (18) having elongate cooling channel openings (19) in the region of a second connecting surface (16) of the second mirror part (14) are formed in the second mirror part (14). The first mirror part (13) and the second mirror part (14) are brought together in such a way that initially a partial region of the first connecting surface (15) and a partial region of the second connecting surface (16) come into contact and form a common contact surface (24), and the common contact surface (24) is enlarged by continuing to bring the first mirror part (13) and the second mirror part (14) together in a direction (25) along the longitudinal extents of the cooling channel openings (19).