Substage Positioning via Passive Magnetic Force Systems

Solution Overview

Problem

Conventional lithographic apparatus positioning systems face challenges with heat generation and structural deformations due to large, powerful actuators, leading to reduced position accuracy and increased mass, which complicates cooling and force distribution.

Innovation Solution

A positioning system utilizing a passive force system with at least two magnet systems that apply non-contact forces to the substage, allowing for zero-force positioning and reduced heat generation, thereby minimizing deformations and improving accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If a large, powerful actuator is used to accelerate the substage, then the positioning force is sufficient, but heat generation increases and structural deformations occur leading to reduced position accuracy

Engineering Contradiction:

Improvepositioning forceVSAvoidposition accuracy

Core Design Contradiction:

ForceVSMeasurement precision

Solution Approach 1:

The positioning system is divided into two independent actuation systems: a long-stroke actuator for coarse positioning of the main stage, and a short-stroke actuator for fine positioning of the substage relative to the main stage. This segmentation allows each actuator to operate at optimal power levels, reducing heat generation and structural deformations while maintaining sufficient positioning force.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent replaces conventional mechanical contact-based actuators with a moving magnet system (MMS) that uses magnetic fields for contactless actuation. The MMS includes a coil system on the stator and magnets on the mover, enabling precise force application without mechanical contact, thereby minimizing structural deformations and improving position accuracy.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Force

If a large, powerful actuator is used to accelerate the substage, then the positioning force is sufficient, but the mass of the substage increases

Engineering Contradiction:

Improvepositioning forceVSAvoidsubstage mass

Core Design Contradiction:

ForceVSWeight of moving object

Solution Approach 1:

The positioning system is divided into two independent actuation systems: a long-stroke actuator for coarse positioning of the main stage, and a short-stroke actuator for fine positioning of the substage relative to the main stage. This segmentation allows each actuator to operate at optimal power levels, reducing heat generation and structural deformations while maintaining sufficient positioning force.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent replaces conventional mechanical contact-based actuators with a moving magnet system (MMS) that uses magnetic fields for contactless actuation. The MMS includes a coil system on the stator and magnets on the mover, enabling precise force application without mechanical contact, thereby minimizing structural deformations and improving position accuracy.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Speed

If the short stroke actuator applies force to accelerate the substage, then positioning is achieved, but a lot of heat is generated causing structural deformations

Engineering Contradiction:

Improveacceleration speedVSAvoidheat generation

Core Design Contradiction:

SpeedVSTemperature

Solution Approach 1:

The patent replaces conventional mechanical contact-based actuators with a moving magnet system (MMS) that uses magnetic fields for contactless actuation. The MMS includes a coil system on the stator and magnets on the mover, enabling precise force application without mechanical contact, thereby minimizing structural deformations and improving position accuracy.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent employs magnetic field parameters instead of mechanical contact parameters for force application. By controlling the current in the coil system and the configuration of magnets, the system can achieve the required acceleration while minimizing heat generation through optimized magnetic field interactions and reduced mechanical friction.

Inventive Principle:

Principle #35Parameter changes

4Temperature

If cooling hoses are provided between the substage and main stage, then heat is removed, but force disturbances occur limiting position accuracy

Engineering Contradiction:

Improveheat removalVSAvoidposition accuracy

Core Design Contradiction:

TemperatureVSMeasurement precision

Solution Approach 1:

The patent extracts the cooling function from the positioning structure by providing cooling channels within the substage itself rather than through hoses between stages. This integration eliminates the hoses that cause force disturbances, while still achieving effective heat removal through the substage's internal cooling pathways.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces a passive force system using magnet assemblies as an intermediary between the substage and main stage. This magnetic coupling provides a contactless force transmission mechanism that does not require physical connection, thereby eliminating force disturbances caused by mechanical linkages while maintaining precise position control.

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

The system achieves precise positioning with reduced heat generation and mass, enhancing accuracy and efficiency by leveraging the passive force system's ability to adjust forces based on substage position, thus overcoming the limitations of conventional active actuator systems.

Implementation Method 1

a passive force system between the substage and the main stage, including at least two magnet systems, each magnet system being configured to apply a force in the moving direction to the substage with respect to the main stage in a non-contact manner

Methodology Applied

Scientific EffectMagnetic force: Magnetic Field

Data Source

PatentUS11460786B2Positioning system and a method for positioning a substage or a stage with respect to a frame

Publication Date: 2022.10.04 ASML NETHERLANDS BV

AI summary

A method for positioning a substage (9), supported by a main stage (5), relative to a reference object, the substage moveable in a direction (7) between a first and second position relative to the main stage. The method includes positioning the first stage using a passive force system that is activated by positioning the main stage. The passive force system includes two magnet systems (119, 121), each magnet system being configured to apply a force in the direction to the first stage with respect to the second stage in a non-contact manner, the forces resulting in a resultant force applied to the first stage in the direction by the passive force system. A magnitude and/or a direction of the resultant force depends on the position of the first stage relative to the second stage, and the first stage has a zero-force position between the first and second position in which the resultant force is zero.