12-Pole Magnetic Beam Corrector for Compact Aberration Control
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Solution Overview
Problem
Charged particle beam apparatuses face challenges in compactly deflecting and correcting beams due to space constraints and beam aberrations introduced by traditional deflectors, which affect resolution and accuracy in high-resolution systems like scanning electron microscopes.
Innovation Solution
A magnetic multipole device with a 12-pole configuration using saddle coils for both deflection and aberration correction, allowing for bi-axial deflection and simultaneous beam correction within a limited space, reducing the need for separate deflector and corrector components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional beam deflectors are used for directing the charged particle beam, then the beam can be deflected to a predetermined position, but beam aberrations such as astigmatism are introduced which degrade resolution
Solution Approach 1:
The patent combines the beam deflection function and beam aberration correction function into a single multipole device. The multipole device includes both deflection coils for directing the beam and correction coils for compensating astigmatism, allowing simultaneous achievement of precise positioning and maintained beam focus quality without requiring separate components
Solution Approach 2:
The multipole device is designed to perform multiple functions: it can deflect the charged particle beam in both x and y directions while simultaneously correcting beam aberrations. This multi-functional design eliminates the need for separate deflector and corrector components, resolving the contradiction between positioning capability and beam quality
2Reliability
If separate beam deflector and beam corrector components are provided, then both deflection and aberration correction can be achieved, but the apparatus occupies considerable space which is limited near the objective lens
Solution Approach 1:
The patent merges the beam deflector and beam corrector into a single integrated multipole device. The deflection coils and correction coils are combined in one structure that occupies minimal space near the objective lens, eliminating the need for separate components and reducing overall apparatus volume while maintaining full correction capability
3Volume of moving object
If an octupole is used as a beam deflector, then space can be reduced, but the sensitivity is limited and beam aberrations are considerable
Solution Approach 1:
The multipole device is designed to provide both high deflection sensitivity and effective aberration correction in a compact form. By optimizing the coil configuration and magnetic field distribution, the device achieves superior performance compared to using an octupole solely for deflection, maintaining high sensitivity while correcting aberrations
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 enables precise beam deflection and correction with reduced space requirements, improving resolution and accuracy while minimizing beam aberrations, and enhancing the sensitivity of the deflection process compared to traditional octupole systems.
Implementation Method 1
a first magnetic deflector for deflecting the charged particle beam in an x-direction, comprising a plurality of first saddle coils; and a second magnetic deflector for deflecting the charged particle beam in a y-direction perpendicular to the x-direction, comprising a plurality of second saddle coils
Implementation Method 2
The plurality of first saddle coils and the plurality of second saddle coils are arranged around the optical axis in a 12-pole magnetic corrector structure with 12 poles provided in uniformly spaced angular intervals
Data Source
AI summary
A magnetic multipole device for influencing a charged particle beam propagating along an optical axis is provided. The magnetic multipole device includes a first magnetic deflector for deflecting the charged particle beam in an x-direction with a plurality of first saddle coils; and a second magnetic deflector for deflecting the charged particle beam in a y-direction perpendicular to the x-direction with a plurality of second saddle coils. The first and second saddle coils are arranged around the optical axis in a 12-pole magnetic corrector structure with 12 poles provided at uniformly spaced angular intervals. The 12-pole magnetic corrector structure is configured to exert a beam correction field of a magnetic 12-pole corrector on the charged particle beam. Further provided are a charged particle beam apparatus with a magnetic multipole device and a method of influencing a charged particle beam propagating along an optical axis with a magnetic multipole device as described herein.