Stage Device Thermal Bypass for Charged Particle Beam Accuracy

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Solution Overview

Problem

In charged particle beam devices like CD-SEM, the XY stage experiences deformation due to temperature increases caused by Joule heat from linear motor coils, affecting measurement accuracy and visual field alignment, especially in high-magnification inspections, as heat cannot be effectively released in vacuum environments.

Innovation Solution

A stage device design featuring a slide unit connected to a rail system with thermal bypass components of varying thermal conductivities, where high thermal conductivity materials are used closer to the slide unit to promote heat release to the base, reducing temperature increases and thermal deformation, and a connecting member arranged orthogonally to the movement directions to regulate displacement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If the coil is used as the moving part of the linear motor to avoid magnetic field interference, then the magnetic field problem is solved, but the coil is integrally connected to the stage causing heat generation to be transmitted to the stage

Engineering Contradiction:

Improvemagnetic field interferenceVSAvoidstage temperature

Core Design Contradiction:

Object-affected harmful factorsVSTemperature

Solution Approach 1:

The connecting member is divided into multiple members with different thermal conductivities. The first connecting member has low thermal conductivity to block heat transmission from the coil to the stage, while the second connecting member has high thermal conductivity to conduct heat away from the coil to the base. This segmentation allows simultaneous achievement of magnetic field avoidance and heat management.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different parts of the connecting structure are assigned different thermal conductivity properties based on their specific functions. The portion closer to the stage uses low thermal conductivity material to protect the stage from heat, while the portion closer to the base uses high thermal conductivity material to dissipate heat. This local differentiation resolves the contradiction between avoiding magnetic field interference and preventing stage overheating.

Inventive Principle:

Principle #3Local quality

2Adaptability or versatility

If the coil is placed in vacuum for stage driving, then the charged particle beam device requirement is met, but heat cannot be released effectively as there is no air for heat transmission

Engineering Contradiction:

Improvevacuum environment compatibilityVSAvoidcoil temperature

Core Design Contradiction:

Adaptability or versatilityVSTemperature

Solution Approach 1:

The second connecting member with high thermal conductivity acts as a thermal intermediary, providing a solid conduction path for heat to travel from the coil in the vacuum environment to the base. This mediator enables effective heat release in vacuum by replacing air convection with direct thermal conduction through the high thermal conductivity member.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Measurement precision

If the stage is moved to high magnification inspection positions, then the measurement capability is improved, but slight deformation of the stage becomes a factor of reduction in measurement accuracy

Engineering Contradiction:

Improvepattern dimension measurement accuracyVSAvoidstage deformation

Core Design Contradiction:

Measurement precisionVSManufacturing precision

Solution Approach 1:

The invention converts the harmful thermal effect into a beneficial heat management system. By strategically placing high and low thermal conductivity members, the system uses thermal conduction to actively manage and redirect heat away from the stage, transforming the potential harmful heat generation into a controlled thermal flow that protects the stage from deformation and maintains measurement precision.

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 design effectively suppresses thermal deformation of the stage, enhancing measurement accuracy by reducing temperature-related errors and maintaining the stability of the stage's position and angle, thus improving the precision of position measurements.

Implementation Method 1

a thermal bypass member arranged in parallel with the connecting member between the coil and the base, the thermal bypass member comprising a material different from that of the connecting member

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS9887064B2Stage device and charged particle beam device using the same

Publication Date: 2018.02.06 HITACHI HIGH TECH CORP

AI summary

To provide a stage device and a charged particle beam device using the same capable of effectively suppressing thermal deformation of a stage generated by temperature increase caused by heat generated by a linear motor. The stage device including a table, a linear motor driving the table in a prescribed direction, in which the table and a moving part of the linear motor are connected by components, a slide unit is attached to the component, movement of which is constrained by a rail fixed to a base, and at the same time, the slide unit is positioned vertically below a place where the component is joined to the table, thereby suppressing thermal deformation of the table.