EUV Final Focus Assembly Hybrid Optics Thermal Protection

Solution Overview

Problem

Current EUV light systems face challenges in effectively focusing amplified light beams onto target materials to produce high-quality EUV plasma, particularly due to issues with thermal degradation and contamination of optical elements, which affect the precision and longevity of the final focus assembly.

Innovation Solution

A hybrid final focus assembly is introduced, comprising a transmissive optical element and a reflective optical element with curved surfaces, where the transmissive element is positioned outside the direct path of the target material and farther from the target location than the reflective element, allowing for precise focusing of the amplified light beam onto the target material while minimizing thermal degradation and contamination risks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a transmissive optical element is used to focus the amplified light beam, then the focusing precision is improved, but the element is subjected to thermal degradation and contamination from target material

Engineering Contradiction:

Improvefocusing precisionVSAvoidthermal degradation and contamination

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The focus assembly is divided into two separate optical elements: a transmissive element for primary focusing and a reflective element for secondary focusing. This segmentation allows each element to perform its specific function while protecting the transmissive element from direct exposure to harmful target material

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The reflective optical element acts as an intermediary between the transmissive element and the target material. It receives the focused beam from the transmissive element, redirects it to the target, and thereby shields the transmissive element from thermal degradation and contamination

Inventive Principle:

Principle #24Intermediary (Mediator)

2Manufacturing precision

If the transmissive optical element is positioned closer to the target location for better focusing control, then the focusing precision is improved, but the exposure to thermal effects and contamination increases

Engineering Contradiction:

Improvefocusing precisionVSAvoidlifetime of optical element

Core Design Contradiction:

Manufacturing precisionVSDuration of action of stationary object

Solution Approach 1:

The focus assembly is divided into two separate optical elements: a transmissive element for primary focusing and a reflective element for secondary focusing. This segmentation allows each element to perform its specific function while protecting the transmissive element from direct exposure to harmful target material

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The reflective optical element acts as an intermediary between the transmissive element and the target material. It receives the focused beam from the transmissive element, redirects it to the target, and thereby shields the transmissive element from thermal degradation and contamination

Inventive Principle:

Principle #24Intermediary (Mediator)

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 enhances the precision and longevity of the final focus assembly by reducing thermal effects and contamination, leading to improved EUV light production and extended lifetime of optical elements, with the amplified light beam being focused to enable efficient conversion of the target material into EUV-emitting plasma.

Implementation Method 1

at least one transmissive optical element having at least one curved surface through which the amplified light beam travels

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 2

at least one reflective optical element having at least one curved surface on which the amplified light beam is reflected

Methodology Applied

Scientific EffectReflection: Reflection

Implementation Method 3

the amplified light beam being focused to enable efficient conversion of the target material into EUV-emitting plasma

Methodology Applied

Scientific EffectLaser ablation: Laser Ablation

Data Source

PatentUS9374882B2Final focus assembly for extreme ultraviolet light source

Publication Date: 2016.06.21 ASML NETHERLANDS BV

AI summary

An extreme ultraviolet light system includes a target material delivery system configured to produce a target material; and a beam delivery system that is configured to receive an amplified light beam emitted from a drive laser system and to direct the amplified light beam toward a target location that receives the target material. The beam delivery system includes a final focus assembly that focuses the amplified light beam at a focal location to enable interaction between the amplified light beam and the target material to cause the target material to be converted into a plasma that emits extreme ultraviolet light. The final focus assembly includes at least one transmissive optical element having at least one curved surface through which the amplified light beam travels; and at least one reflective optical element having at least one curved surface on which the amplified light beam is reflected.