Electrostatic Lens Magnetic Alignment for Charged Particle Beam Aberration
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Solution Overview
Problem
Existing charged particle beam devices face challenges in preventing geometric aberration due to axis deviations in electrostatic lenses, which can lead to decreased spatial resolution and increased machining complexity, especially when using three-dimensional measuring machines for alignment.
Innovation Solution
Incorporating magnetic field generating elements along the outer periphery of electrodes in the electrostatic lens, particularly on the electrode to which a voltage is applied, to correct deflection fields caused by axis deviations, thereby minimizing both geometric and chromatic aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If three-dimensional measuring machine is used to align center holes of electrodes, then axis deviation can be adjusted to several micrometers, but foreign substances may remain on electrode surface or damage may be caused on electrode surface
Solution Approach 1:
The patent replaces the mechanical alignment method using a three-dimensional measuring machine with a magnetic field-based alignment method. Magnetic field generating elements generate a magnetic field that aligns the center holes of electrodes coaxially without physical contact, thereby avoiding foreign substance contamination and surface damage while achieving precise alignment.
Solution Approach 2:
The patent introduces a magnetic field as an intermediary between the alignment system and the electrodes. The magnetic field generating elements create a magnetic field that acts as a mediator to align the center holes without direct mechanical contact, preventing contamination and damage that would occur with probe-based mechanical alignment.
2Manufacturing precision
If strict machining tolerance is imposed on each component, then axis deviation of center hole can be reduced, but yield of machining process may be decreased and failure during assembly may be caused
Solution Approach 1:
The patent replaces strict mechanical machining tolerance requirements with a magnetic field-based alignment system. Instead of requiring components to be machined with very tight tolerances, the magnetic field generating elements automatically align the center holes coaxially during assembly, significantly reducing machining complexity and improving yield while maintaining high alignment precision.
Solution Approach 2:
The patent changes the alignment parameter from mechanical dimensional tolerance to magnetic field-based positional adjustment. By using magnetic field generating elements that can be adjusted to create the appropriate magnetic field, the system achieves precise coaxial alignment without requiring strict machining tolerances on the electrode components.
3Manufacturing precision
If magnetic field generating elements are disposed along outer periphery of electrode, then geometric aberration is prevented, but device complexity increases
Solution Approach 1:
The patent makes the electrode serve multiple functions: it acts as both the electrostatic lens component and the magnetic field generating element. By forming the electrode from a magnetic body and disposing magnetic field generating elements along its outer periphery, the same component structure achieves both electrostatic focusing and magnetic alignment functions, minimizing additional complexity while preventing geometric aberration.
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 approach effectively prevents geometric aberration and maintains high spatial resolution by aligning the axes of electrostatic lenses with high accuracy, improving the performance of charged particle beam devices like scanning electron microscopes.
Implementation Method 1
two or more magnetic field generating elements are disposed along an outer periphery of the electrode
Implementation Method 2
The focusing field of the electrostatic lens is formed by a potential gradient generated between the plurality of electrodes to which different voltages are applied
Implementation Method 3
The scanning electron microscope focuses the electron beam by generating a focusing field using an electromagnetic lens or an electrostatic lens
Data Source
AI summary
To provide a charged particle beam device capable of preventing generation of geometric aberration by aligning axes of electrostatic lenses with high accuracy even when center holes of respective electrodes which constitute the electrostatic lens are not disposed coaxially. The charged particle beam device according to the invention includes an electrostatic lens disposed between an acceleration electrode and an objective lens, wherein at least one of the electrodes which constitutes the electrostatic lens is formed of a magnetic body, and two or more magnetic field generating elements are disposed along an outer periphery of the electrode.