Charged Particle Beam Aberration Control for A4 and A3 Astigmatism
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Solution Overview
Problem
Current charged particle beam devices, such as transmission electron microscopes, are unable to correct five-fold fourth-order astigmatism (A4) while maintaining the correction of four-fold third-order astigmatism (A3), which limits the resolution of observation images.
Innovation Solution
A charged particle beam device with an aberration corrector that includes a transmission lens between two multipoles, deflectors to adjust beam angles, and a control unit to adjust these angles to correct A4 and A3, using specific equations to calculate and apply changes to the beam angles θ1 and θ2.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the charged particle beam is swung back to the optical axis to prevent extra parasitic aberration, then parasitic aberration is reduced, but the ability to correct A4 is limited
Solution Approach 1:
The patent introduces dynamic angle adjustment capability, allowing the charged particle beam to be inclined at controlled angles θ1 and θ2 relative to the optical axis rather than being strictly confined to the axis. This dynamic positioning enables access to different correction regimes that were previously unavailable when the beam was constrained to the optical axis
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
Enables the correction of five-fold fourth-order astigmatism (A4) while maintaining the correction of four-fold third-order astigmatism (A3), thereby improving the resolution of observation images generated by the device.
Implementation Method 1
a first deflector configured to adjust an angle θ1 between a charged particle beam incident on a first multipole and an optical axis
Implementation Method 2
a second deflector configured to adjust an angle θ2 between a charged particle beam incident on a second multipole and the optical axis
Implementation Method 3
an aberration corrector including a transmission lens disposed between a first multipole and a second multipole
Data Source
AI summary
There is provided a charged particle beam device including an aberration corrector including a transmission lens disposed between a first multipole and a second multipole in order to correct five-fold fourth-order astigmatism (A4) while maintaining correction of four-fold third-order astigmatism (A3), and the charged particle beam device further includes: a first deflector configured to adjust an angle θ1 between a charged particle beam incident on the first multipole and an optical axis; a second deflector configured to adjust an angle θ2 between a charged particle beam incident on the second multipole and the optical axis; and a control unit configured to control the first deflector and the second deflector. The control unit changes the angle θ1 so as to correct the five-fold fourth-order astigmatism, and changes the angle θ2 so as to correct the four-fold third-order astigmatism that occurs due to a change in the angle θ1.