Immersion Lithography Fluid Contamination Detection

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Solution Overview

Problem

Existing immersion lithographic apparatuses face challenges in maintaining performance over time due to contamination and fluid containment issues in the fluid handling system, leading to unpredictable effects and reduced efficiency.

Innovation Solution

A method is introduced to detect contamination and fluid containment performance by measuring parameters such as heat loss, pressure variations, contaminant particle count, flow rate, and force applied to the fluid handling system, generating signals when thresholds are exceeded to alert for necessary remedial actions like cleaning or system adjustments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a liquid confinement system is used to provide liquid on a localized area of the substrate, then the turbulence and contamination issues are reduced, but the system complexity increases due to additional components like inlets, outlets, and confinement structures

Engineering Contradiction:

Improvefluid containment stabilityVSAvoidfluid handling system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The liquid confinement system is designed to automatically detect contamination and maintain fluid containment without requiring manual intervention. The system monitors its own performance and self-regulates to maintain reliability, reducing the need for complex external monitoring and control mechanisms.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The system incorporates feedback mechanisms that monitor fluid containment performance and automatically adjust operation parameters to maintain optimal containment. This feedback loop ensures reliability while keeping the control system manageable by using intelligent algorithms rather than complex hardware.

Inventive Principle:

Principle #23Feedback

2Productivity

If the substrate is scanned at high speed during exposure, then the productivity increases, but the fluid containment becomes more difficult to maintain due to centrifugal forces and turbulence

Engineering Contradiction:

Improvesubstrate scanning speedVSAvoidfluid containment stability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The liquid confinement system is designed with dynamic characteristics that allow it to adapt to varying scanning speeds. The system can adjust its confinement parameters in real-time to maintain fluid stability even at high substrate scanning speeds, balancing productivity with containment reliability.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes operational parameters such as liquid flow rate, pressure, and confinement force dynamically based on the substrate scanning speed. When scanning speed increases, the system adjusts parameters to compensate for increased centrifugal forces and maintain fluid containment stability.

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If immersion liquid is used to reduce wavelength and improve resolution, then the manufacturing precision improves, but the system becomes more susceptible to contamination and performance degradation over time

Engineering Contradiction:

Improvefeature imaging resolutionVSAvoidsystem performance consistency

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The system extracts and removes contaminant particles from the immersion liquid continuously during operation. By actively extracting contaminants rather than relying solely on prevention, the system maintains both the resolution benefits of immersion liquid and the performance consistency required for reliable manufacturing.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The system converts the potential harm of contamination into a benefit by using the presence of contaminants as a signal to activate cleaning and filtration mechanisms. The contamination detection system triggers automated responses that actually improve fluid quality and maintain imaging precision over time.

Inventive Principle:

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

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 enables timely detection and mitigation of contamination, maintaining optimal fluid containment and system performance, thereby ensuring consistent and efficient operation of the immersion lithographic apparatus.

Implementation Method 1

measuring a performance parameter of the fluid handling system indicative of a level of containment of fluid between the fluid handling system and a substrate and/or substrate table

Methodology Applied

Scientific EffectPressure differential: Pressure Gradient

Implementation Method 2

detecting a change in heat loss from a component during operation of the fluid handling system

Methodology Applied

Scientific EffectHeat loss detection: Thermal Radiation

Implementation Method 3

detecting a pressure variation and/or flow rate variation in fluid passing through an outlet and/or an inlet of the fluid handling system

Methodology Applied

Scientific EffectPressure variation: Pressure Gradient

Data Source

PatentUS8587762B2Methods relating to immersion lithography and an immersion lithographic apparatus

Publication Date: 2013.11.19 ASML NETHERLANDS BV

AI summary

A method of operating a fluid confinement system of an immersion lithographic apparatus is disclosed. The performance of the liquid confinement system is measured in several different ways. On the basis of the result of the measurement of performance, a signal indicating, for example, that a remedial action may need to be taken is generated.