Stage Apparatus Thermal Isolation for Charged Particle Beam
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Solution Overview
Problem
Charged particle beam apparatuses face challenges in maintaining high positioning accuracy due to heat generated by linear motor coils, which causes thermal expansion and potential misalignment of semiconductor wafers during measurement in high vacuum environments, where conventional heat dissipation methods are ineffective.
Innovation Solution
A stage apparatus with a configuration that interposes at least two components between the heat-generating linear motor coil and the sample stage, using a high heat conductivity material for one component to direct heat away from the sample stage, and a low heat conductivity material for the other to minimize heat transfer to the sample, while guiding heat through a slide unit and rail system to dissipate it effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a linear motor is used to drive the stage for high speed and high accuracy positioning, then positioning speed and accuracy are improved, but heat is generated by the coil and magnet which causes thermal expansion and reduces measurement accuracy
Solution Approach 1:
The patent introduces a magnet as an intermediary component between the coil and the stage. The magnet is fixed to the stage while the coil remains stationary, allowing the magnetic field to transmit force without direct thermal contact. This mediator approach enables the coil-generated heat to be isolated from the stage, resolving the contradiction between high-speed positioning capability and heat-induced thermal expansion.
Solution Approach 2:
The patent replaces traditional mechanical transmission systems (ball screws, gears) with a direct linear motor drive system where the magnetic field directly actuates the stage. This substitution eliminates mechanical friction and associated heat generation from intermediate components, while the only heat source (coil) is thermally isolated through the intermediary magnet design.
2Loss of energy
If conventional heat dissipation methods are used in high vacuum environment, then heat can be dissipated to surrounding air, but high vacuum atmosphere prevents heat dissipation by transfer to air
Solution Approach 1:
The patent extracts the heat dissipation function from the vacuum environment by designing the coil to be thermally isolated from the vacuum chamber components. The coil is positioned outside or thermally decoupled from the vacuum space, allowing heat to be dissipated to the external environment rather than being trapped in the vacuum where it would otherwise have nowhere to go. This extraction resolves the contradiction by providing a heat dissipation path that does not depend on the vacuum atmosphere.
3Power
If the coil and stage are directly connected for efficient force transmission, then drive efficiency is improved, but heat transfer from coil to stage causes thermal expansion and positioning errors
Solution Approach 1:
The magnet serves as a thermal intermediary that transmits mechanical force efficiently while blocking heat transfer. By fixing the magnet to the stage and keeping the coil stationary, the system achieves direct force transmission (high drive efficiency) through the magnetic field, while the physical separation prevents conductive heat transfer from the coil to the stage, maintaining positioning accuracy.
Solution Approach 2:
The patent separates the thermal and mechanical dimensions by positioning the coil in a different spatial location than the stage. The magnetic field acts as a non-contact force transmission medium, allowing force to be transmitted in one dimension (mechanical drive) while thermal energy is confined to another dimension (coil housing), preventing heat transfer to the stage and maintaining positioning precision.
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 effectively suppresses heat transfer to the sample stage, preventing thermal deformation and ensuring high accuracy positioning and measurement by redirecting heat away from the sample stage, thus maintaining precise alignment and reducing temperature increases.
Implementation Method 1
the coil and magnet as basic elements of the linear motor generate heat. Specifically, as current flows through the coil, Joule heat is produced by the electric resistance of the coil.
Implementation Method 2
using a high heat conductivity material for one component to direct heat away from the sample stage
Implementation Method 3
a low heat conductivity material for the other to minimize heat transfer to the sample
Implementation Method 4
guiding heat through a slide unit and rail system to dissipate it effectively
Data Source
AI summary
The purpose of the present invention is to provide a stage apparatus that effectively suppresses the transmission of heat generated by a drive mechanism to a sample, and a charged particle beam apparatus using the same. In order to achieve the purpose, there are proposed a stage apparatus and a charged particle beam apparatus. The stage apparatus comprises a table; a drive source that drives the table in a predetermined direction; a first connection member provided between the table and the drive source; a second connection member provided between the table and the drive source and closer to the drive source than the first member; a slide unit supported by the second connection member; and a rail guiding the slide unit in a predetermined direction, the first connection member comprising a member having a relatively low heat conductivity with respect to the second connection member.