Stage Apparatus Thermal Deformation Control
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Solution Overview
Problem
Conventional stage apparatuses in charged particle beam systems face challenges in maintaining positional accuracy due to thermal deformation caused by heat generation, which leads to temperature rises and subsequent thermal expansion, affecting the precision of semiconductor device inspections.
Innovation Solution
A stage apparatus with a three-axis movement system, utilizing a ceramic composite material for the upper and middle stages and aluminum or aluminum alloy for the lower stage, along with a guide mechanism to reduce flexural rigidity and a mirror for position identification, to control and minimize thermal deformation and heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a stage apparatus operates in a high-vacuum environment, then charged particle beam inspection is enabled, but heat dissipation is impaired due to absence of convective heat transfer
Solution Approach 1:
The patent changes the material parameters of the stage from conventional metals to ceramic composite materials with specific thermal properties (low thermal expansion coefficient and controlled thermal conductivity). This allows the stage to maintain dimensional stability under vacuum conditions while managing heat dissipation through thermal conduction to the base, resolving the temperature control issue in high-vacuum environments.
Solution Approach 2:
The patent employs ceramic composite materials for the stage structure, combining ceramic particles or fibers in a metal matrix or as monolithic structures. These composite materials provide both the mechanical strength required for vacuum operation and controlled thermal properties that enable heat management through conduction to the base, eliminating reliance on convective cooling.
2Strength
If conventional metal materials are used for the stage, then mechanical strength is sufficient, but thermal expansion causes positioning errors
Solution Approach 1:
The patent fundamentally changes the material parameters by selecting ceramic composite materials with thermal expansion coefficients one to two orders of magnitude lower than conventional metals. This parameter change enables the stage to maintain sub-micrometer dimensional stability during temperature variations, ensuring positioning accuracy without sacrificing mechanical strength.
Solution Approach 2:
The patent applies different material compositions to different parts of the stage structure, optimizing local thermal and mechanical properties. The ceramic composite material composition can be varied in different regions to balance structural strength requirements with thermal expansion control, achieving both mechanical integrity and positioning precision.
3Manufacturing precision
If ceramic materials with low thermal conductivity are used, then thermal expansion is reduced, but heat accumulates in the stage
Solution Approach 1:
The patent segments the thermal management function from the structural function. The stage body uses ceramic composite materials for dimensional stability, while thermal conduction paths are created through the base structure and support mechanisms. This segmentation allows heat to be conducted away from the stage through dedicated thermal pathways without compromising the low-expansion properties of the stage material.
Solution Approach 2:
The patent introduces the base structure as a thermal intermediary that receives heat from the stage through controlled conduction. The base acts as a heat sink and distribution mechanism, transferring heat away from the stage components while the stage material itself maintains its low thermal expansion characteristics. This intermediary approach decouples thermal management from structural material selection.
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 enables high-accuracy positioning of samples by reducing thermal deformation and temperature rise, thereby improving the precision of semiconductor device inspections and maintaining the shape and position of the stage, even in a vacuum environment.
Implementation Method 1
The temperature rise occurring in each of components of the stage causes thermal expansion corresponding to the temperature rise, and the difference in expansion amount of each of the components and the constrained state of the assembled apparatus would lead to complicated thermal deformation of the stage.
Implementation Method 2
the table of the lower stage includes a component using aluminum or an aluminum alloy
Implementation Method 3
a guide mechanism that guides the middle stage in the moving direction are coupled with each other via a mechanism to reduce flexural rigidity in a rotational direction with respect to the moving axis
Implementation Method 4
a mirror is installed in the upper table, and the position of the sample is identified on the basis of the distance measurement of the reflecting surface of the mirror
Data Source
AI summary
Provided is a stage apparatus that reduces thermal deformation and temperature rise in an upper table on which a sample is mounted and a charged particle beam apparatus including the stage apparatus. The stage apparatus includes: an upper stage that moves an upper table on which a sample is mounted in a first direction; a middle stage that moves a middle table on which the upper stage is mounted in a second direction orthogonal to the first direction; and a lower stage that moves a lower table on which the middle stage is mounted in a third direction orthogonal to the first direction and the second direction. The upper table and the middle table use a material having a smaller thermal expansion coefficient than in a material of the lower table, and the lower table uses a material having higher thermal conductivity than in the material of the upper table and the middle table.