Magnetic Levitation Stage Device for Charged Particle Beam Positioning

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Solution Overview

Problem

Conventional stage devices for semiconductor wafer positioning suffer from drive characteristic degradation due to water-cooled pipes and minute vibrations caused by current amplifier noise, along with difficulties in suppressing leakage magnetic fields, which hinder accurate positioning and application in charged particle beam devices.

Innovation Solution

A magnetic levitation flat stage device with a movable portion supported by both first and second magnets, where the first magnets face a top plate made of magnetic material and the second magnets face coils on a bottom plate, reducing the need for refrigerant pipes and minimizing current flow, and a magnetic shield is used to contain the magnetic field, thereby reducing noise and leakage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If water-cooled pipes are used to cool coils, then heat dissipation is improved, but drive characteristics deteriorate due to pipe resistance

Engineering Contradiction:

Improvecoil temperatureVSAvoiddrive characteristic

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The invention extracts and removes the water-cooled pipes from the system entirely. Instead of cooling the coils through water circulation with pipes that create resistance, the patent uses natural air cooling or radiation cooling of the coils, eliminating the source of drive characteristic deterioration while still managing heat dissipation.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention replaces the mechanical water cooling system with a passive thermal management approach. The coils are designed to dissipate heat through their surface area and ambient air convection, substituting the active mechanical cooling system with a simpler thermal design that avoids introducing resistance elements into the drive path.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Force

If current amplifiers are used to drive coils, then magnetic field generation is improved, but minute vibrations occur due to amplifier noise

Engineering Contradiction:

Improvemagnetic forceVSAvoidpositioning stability

Core Design Contradiction:

ForceVSReliability

Solution Approach 1:

The invention replaces expensive, noisy current amplifiers with simple DC power supplies that provide stable current without the noise characteristics of amplifiers. The patent uses direct current sources that are inherently quieter and more stable for maintaining magnetic field strength, eliminating the vibration problem caused by amplifier noise.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Force

If magnetic fields are generated for levitation, then positioning capability is improved, but magnetic field leakage occurs affecting charged particle beams

Engineering Contradiction:

Improvelevitation forceVSAvoidmagnetic field leakage

Core Design Contradiction:

ForceVSObject-generated harmful factors

Solution Approach 1:

The invention introduces magnetic shields as intermediary elements between the magnetic levitation system and the charged particle beam path. These shields, made of high-permeability magnetic materials, act as mediators that redirect and contain the magnetic field lines, preventing them from leaking into the charged particle beam region while maintaining the levitation force.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention applies magnetic shielding materials selectively in specific regions where field leakage would affect charged particle beams. The shields are positioned strategically around the coil assemblies, providing localized magnetic field containment only where needed, without interfering with the overall levitation functionality.

Inventive Principle:

Principle #3Local quality

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 positioning accuracy, reduces vibrations, and minimizes magnetic field leakage, allowing for precise positioning and improved application in charged particle beam devices.

Implementation Method 1

a plurality of first magnets that are mounted on an upper surface of the support portion, face the top plate, and generate a first thrust force against the top plate

Methodology Applied

Scientific EffectMagnetic attraction: Magnetism

Implementation Method 2

a plurality of second magnets that are provided on a lower surface of the support portion, face the coil, and generate a second thrust force against the coil

Methodology Applied

Scientific EffectElectromagnetic force: Lorentz Force

Data Source

PatentEP4404249A1Stage device, charged particle beam device, and vacuum device

Publication Date: 2024.07.24 HITACHI LTD

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AI summary

Provided is a stage device capable of appropriately positioning an object. Thus, a stage device (10) is provided with: a fixed unit (20) including a top plate (22) including a magnetic material, a bottom plate (26) opposing the top plate (22), and a plurality of coils (28) provided on an upper surface of the bottom plate (26); and a movable unit (100) comprising a support portion (101) for supporting an object (160) to be positioned, a plurality of first magnets (141) mounted to the upper surface of the support portion (101) and opposed to the top plate (22) to generate a first propulsion force (FA) against the top plate (22), and a plurality of second magnets (105) provided on a lower surface of the support portion (101) and opposed to the coil (28) to generate a second propulsion force (FB) between the coil (28) and the plurality of second magnets (105).