Axial-Magnet Weight Compensation With Low Stray Fields
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Solution Overview
Problem
Existing weight compensating devices in projection exposure apparatuses for semiconductor lithography generate significant stray fields, leading to electromagnetic crosstalk and increased complexity, and have manufacturing challenges due to the use of radially magnetized permanent magnetic rings.
Innovation Solution
A weight compensating device with a stator and translator, featuring a first permanent magnet arrangement with axial magnetization, a second radially surrounding magnet arrangement, a third coaxially arranged magnet with inverse axial magnetization, and a magnetic body arrangement, forming a magnetic unit that counteracts weight with reduced stray fields and simplified manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If radially magnetized permanent magnetic rings are used in weight compensating devices, then weight compensation is achieved, but manufacturing complexity increases and stray fields are generated
Solution Approach 1:
The patent changes the magnetization direction from radial to axial, and arranges magnets in alternating polarity patterns (North-South-North-South) around the translator. This parameter change in magnetization configuration reduces manufacturing complexity while maintaining weight compensation capability and significantly reducing stray fields.
2Force
If weight compensating devices with high power are used to handle larger and heavier optical elements, then weight compensation performance is improved, but stray fields become more pronounced causing electromagnetic crosstalk
Solution Approach 1:
The patent converts the potentially harmful stray fields into a beneficial configuration by using alternating polarity arrangements. The opposing magnetic fields from adjacent magnets with opposite polarities cancel each other out, transforming the harmful stray field effect into a useful field cancellation mechanism that reduces electromagnetic crosstalk while maintaining strong weight compensation force.
3Object-generated harmful factors
If soft magnetic shields are used to minimize stray fields, then stray field reduction is achieved, but hysteresis effects are generated and response behavior is impaired
Solution Approach 1:
The patent replaces the mechanical/physical approach of using soft magnetic shields with a magnetic field configuration approach. Instead of relying on magnetic shielding materials that introduce hysteresis, the invention uses carefully arranged permanent magnets with alternating polarities to inherently cancel stray fields, thus eliminating hysteresis effects and improving response behavior while achieving stray field reduction.
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
The solution results in a significantly smaller stray field, improved performance, and reduced manufacturing complexity, with a compact design and low inertia, allowing for efficient weight compensation and reduced thermal loads in projection exposure apparatuses.
Implementation Method 1
The first permanent magnet arrangement, the second permanent magnet arrangement, the third permanent magnet arrangement and the magnetic body arrangement form a magnetic unit and, in interaction with one another, form a compensating force that counteracts the weight acting on the translator
Implementation Method 2
a compensating force that counteracts the weight acting on the translator
Data Source
AI summary
A weight compensating device includes a stator and a translator. The translator is movable relative to the stator along a movement axis. The translator includes a first permanent magnet arrangement with an axial magnetization. The stator includes a second permanent magnet arrangement radially surrounding the first permanent magnet arrangement. The stator includes a third permanent magnet arrangement that is coaxially below the first permanent magnet arrangement and that has an axial magnetization aligned in inverse fashion with respect to the axial magnetization of the first permanent magnet arrangement. The stator includes a magnetic body arrangement that is coaxially above the first permanent magnet arrangement. The first permanent magnet arrangement, the second permanent magnet arrangement, the third permanent magnet arrangement and the magnetic body arrangement form a magnetic unit and, in interaction with one another, form a compensating force that counteracts the weight acting on the translator.