Chuck Interface Mirror Thermal Expansion Matching
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Solution Overview
Problem
Scanning electron microscopes face uncertainty in determining the location of a chuck due to unpredicted relative movements and deformations caused by thermal expansion differences between the chuck, interferometer mirrors, and metal coupling elements, leading to inaccuracies in positioning.
Innovation Solution
A chuck interface with a mirror and inner surface mechanically coupled to the chuck, where the thermal expansion coefficients of the chuck and mirror differ by no more than 0.5 micron*Kelvin per Meter, using ceramic materials like Alumina or BK glass, to minimize thermal-induced deformations and movements, and additional interfacing elements for secure attachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metal coupling elements are used to mechanically couple the interferometer mirrors to the mechanical stage, then the mirrors can be securely attached and moved with the stage, but thermal expansion differences cause unpredicted relative movements and deformations
Solution Approach 1:
The patent changes the material parameter (thermal expansion coefficient) of the coupling element by using a ceramic material instead of metal. This parameter change ensures that the coupling element has a thermal expansion coefficient matching that of the chuck, thereby eliminating thermal expansion-induced relative movements and deformations during heating, while maintaining secure attachment of the interferometer mirrors to the mechanical stage.
2Manufacturing precision
If the mechanical stage is moved to position the chuck, then the chuck can be positioned accurately, but the movement heats the stage, chuck, and coupling elements causing thermal expansion
Solution Approach 1:
The patent changes the thermal parameter of the coupling element by selecting a ceramic material with a thermal expansion coefficient that matches the chuck. This ensures that during mechanical stage movement and subsequent heating, the coupling element and chuck expand at the same rate, preventing relative movement and maintaining positioning accuracy despite temperature increases.
3Adaptability or versatility
If different materials are used for the chuck and interferometer mirrors, then each component can be optimized for its specific function, but differences in thermal expansion coefficients cause deformations and unpredicted movements
Solution Approach 1:
The patent introduces a ceramic coupling element as an intermediary component between the chuck and the interferometer mirrors. This intermediary material serves as a thermal expansion buffer, matching the chuck's thermal properties to eliminate relative movements caused by differential expansion, while still allowing the mirrors and chuck to be made of different optimized materials.
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 solution significantly reduces the uncertainty in determining the chuck's location by minimizing thermal expansion-induced movements and deformations, enhancing the accuracy of interferometer measurements.
Implementation Method 1
Differences between the thermal expansion coefficients of the chuck, the interferometer mirrors and the metal coupling element cause the interferometers mirrors to be deformed and/or to move in relation to the chuck in an unpredicted manner
Data Source
AI summary
A chuck interface that includes a mirror; an inner surface that is shaped and sized to match a portion of a sidewall of a chuck; wherein the inner surface is mechanically coupled to the mirror; and at least one interfacing element for assisting in attaching the chuck to the mirror; and wherein a difference between a thermal expansion coefficient of the chuck and a thermal expansion coefficient of the mirror does not exceed 0.5 micron*Kelvin per Meter.