Lithography Protective Cover Clamping Without External Voltage

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Solution Overview

Problem

Lithographic apparatuses operating at low pressures face challenges in clamping components like reticles and protective plates without applying external forces or voltages, as traditional methods are unsafe and prone to contamination issues.

Innovation Solution

The use of a protective cover with a contact surface coated with thin-film electrets that adheres to the component or support structure without external force, utilizing electrostatic attraction for clamping, and alternative coatings for contact electrification or adhesion, such as polyurethane or metallic coatings for inter-metallic bonding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If electrostatic clamping with high voltages is used to hold components in place in low-pressure environments, then the component can be securely clamped, but safety risks increase due to voltages exceeding intrinsically safe limits

Engineering Contradiction:

Improvecomponent clamping reliabilityVSAvoidelectrostatic safety risk

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the electrostatic field-based clamping system with a magnetic field-based clamping system. Instead of using high voltages to create electrostatic attraction, the invention uses permanent magnets or electromagnets to generate magnetic fields that attract ferromagnetic components, achieving secure clamping without dangerous voltages.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the physical parameter used for clamping from electrical voltage (electrostatic) to magnetic field strength. By transitioning from electrostatic forces (which require high voltages exceeding 250V) to magnetic forces (which can be generated at safe voltage levels), the system maintains clamping reliability while eliminating safety hazards.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If vacuum clamping is used to hold reticles and protective plates, then the components can be securely clamped at atmospheric pressure, but the method becomes ineffective in low-pressure environments where sufficient pressure differential cannot be created

Engineering Contradiction:

Improvecomponent clamping reliabilityVSAvoidoperational pressure range

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent changes the fundamental physical parameter used for clamping from pressure differential (vacuum clamping) to magnetic field interaction. Since magnetic fields do not depend on atmospheric pressure to function, this allows the clamping system to operate reliably across the full pressure range from atmospheric to low-pressure conditions.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the pressure-based mechanical clamping system with a magnetic field-based system. This substitution enables the system to function in low-pressure environments where vacuum clamping fails, as magnetic forces remain effective regardless of ambient pressure.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If mechanical contact methods are used to protect components during transport and handling, then physical protection is provided, but mechanical wear and particle generation occur that can contaminate the system

Engineering Contradiction:

Improvecomponent protectionVSAvoidcontamination from wear particles

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent replaces mechanical contact-based protection with magnetic field-based holding. By using magnetic forces to secure components during transport and handling, the system eliminates mechanical friction and wear that would otherwise generate contaminating particles, while still providing secure physical retention.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

Enables secure clamping of components in low-pressure environments without external forces or voltages, reducing contamination risks and mechanical wear, and allowing for safe operation during flushing, venting, and transport.

Implementation Method 1

the protective cover having a contact surface which is arranged to adhere to a first surface of at least part of said lithographic apparatus or said component... utilizing electrostatic attraction for clamping

Methodology Applied

Scientific EffectElectrostatic attraction: Electrostatics

Implementation Method 2

alternative coatings for contact electrification or adhesion

Methodology Applied

Scientific EffectContact electrification: Triboelectric Effect

Data Source

PatentUS12001149B2Component for use in a lithographic apparatus, method of protecting a component and method of protecting tables in a lithographic apparatus

Publication Date: 2024.06.04 ASML NETHERLANDS BV

AI summary

A method of protecting a component of a lithographic apparatus, the method including the steps of: providing a protective cover which is shaped to protect at least part of said component, the protective cover having a contact surface which is arranged to adhere to a first surface of at least part of said lithographic apparatus or said component; and bringing the protective cover into proximity with the component so as to cause the contact surface to adhere to the lithographic apparatus or said component and remain adhered without the application of external force. It is also provided a patterning device for use in a lithographic apparatus and a lithographic apparatus.