Reluctance Actuator Gap Design for Optical Positioning

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Solution Overview

Problem

Current actuator units for positioning optical elements in lithographic systems are inadequate in minimizing mechanical and thermal disturbances, particularly at higher frequencies, due to the transmission of vibrations and thermal energy through mechanical couplings.

Innovation Solution

The use of a reluctance actuator unit with a first stator part and a first mover part separated by a gap, where the stator part is configured to exert a magnetic force along a line of actuation that moves with the mover part, reducing unwanted variations and deformations without mechanical couplings, and optionally incorporating auxiliary actuators to reduce the gap and power dissipation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If mechanical couplings are used to connect the actuator to the optical element, then the actuator can effectively transmit force, but mechanical and thermal disturbances are transmitted to the optical element

Engineering Contradiction:

Improveforce transmissionVSAvoidmechanical and thermal disturbances

Core Design Contradiction:

ForceVSObject-affected harmful factors

Solution Approach 1:

The patent replaces mechanical couplings with a magnetic field-based actuation system. The actuator uses magnetic forces to position the optical element without physical contact between the actuator and the optical element, thereby eliminating the transmission of mechanical vibrations and thermal energy through mechanical connections.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a magnetic field as an intermediary between the actuator and the optical element. The magnetic field serves as the medium to transmit force without requiring direct mechanical contact, thus avoiding the transmission of harmful mechanical and thermal disturbances.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If the gap between stator and mover parts is reduced to improve actuator performance, then positioning precision improves, but power dissipation increases

Engineering Contradiction:

Improvepositioning precisionVSAvoidpower dissipation

Core Design Contradiction:

Measurement precisionVSLoss of energy

Solution Approach 1:

The patent employs dynamic gap control where the gap between stator and mover parts is adjusted based on operational requirements. The gap can be reduced during positioning operations to improve precision, then increased during idle periods to reduce power dissipation, allowing the system to optimize between precision and energy consumption dynamically.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the gap parameter dynamically to balance positioning precision and power dissipation. By adjusting the gap size according to operational needs, the system achieves high positioning precision when required while minimizing energy loss during normal operation.

Inventive Principle:

Principle #35Parameter changes

3Speed

If the actuator operates at higher frequencies to improve response speed, then positioning speed improves, but mechanical disturbances increase

Engineering Contradiction:

Improvepositioning speedVSAvoidmechanical disturbances

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The patent replaces mechanical actuation with magnetic field-based actuation, enabling high-frequency operation without generating mechanical disturbances. The magnetic field can respond rapidly to control signals without the mechanical inertia and vibration issues that limit traditional mechanical actuators at high frequencies.

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

This solution minimizes mechanical and thermal disturbances to the optical elements, allowing for more precise positioning and reduced power dissipation, enabling the actuator unit to operate effectively over a broader frequency range.

Implementation Method 1

the first stator part is constructed and arranged to exert a magnetic force on the first mover part along a first line of actuation

Methodology Applied

Scientific EffectMagnetic force: Lorentz Force

Implementation Method 2

minimizing mechanical and thermal disturbances to the optical elements, allowing for more precise positioning and reduced power dissipation

Methodology Applied

Scientific EffectThermal energy transmission: Conduction (thermal)

Data Source

PatentUS20240402611A1Actuator unit for positioning an optical element

Publication Date: 2024.12.05 ASML NETHERLANDS BV

AI summary

Disclosed is an actuator unit for positioning an optical element including a reluctance actuator comprising a first stator part and a first mover part that are separated by a gap with respect to each other in a first direction. The first mover part is configured to move the optical element. The first stator part is configured to move the first mover part in a second direction that is different from the first direction. The first stator part comprises at least one stator pole. The first mover part comprises at least one mover pole facing the at least one stator pole. Viewed from the second direction, a width of the at least one mover pole along the second direction is smaller than a width of the at least one stator pole along the second direction.