Electrostatic Prism and Hexapole Layout for Beam Aberration Correction
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Solution Overview
Problem
Charged particle microscope systems face limitations due to spherical and chromatic aberrations in charged particle beams, which restrict higher opening angles, inhibit resolution, and reduce probe current.
Innovation Solution
The use of a plurality of electrostatic elements, including electrostatic multipole elements and a corrector electrostatic prism, to deflect the charged particle beam along an α-shaped path, partially correcting axial chromatic and spherical aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If round lenses are used to direct charged particle beams, then the beam can be focused, but spherical and chromatic aberration coefficients become positive, restricting higher opening angles and inhibiting resolution
Solution Approach 1:
The patent employs asymmetric electrostatic lens designs with non-circular electrode configurations to generate negative aberration coefficients that counterbalance the positive aberrations from conventional round lenses. The electrostatic elements feature asymmetric field distributions that enable correction of both spherical and chromatic aberrations simultaneously, breaking the symmetry constraint that limits conventional lens performance
Solution Approach 2:
The patent utilizes variable electrostatic field parameters through adjustable voltage applied to the electrostatic elements. By dynamically changing the electrostatic field strength and distribution parameters, the system can optimize aberration correction across different operating conditions, enabling higher opening angles while maintaining resolution
2Quantity of substance
If conventional lenses are used, then the system structure remains simple, but probe current is inhibited and opening angles are restricted
Solution Approach 1:
The electrostatic elements serve multiple functions simultaneously: they act as focusing lenses, aberration correctors, and beam shape controllers. This multi-functionality allows the system to increase probe current and opening angles without adding separate correction devices, thereby managing complexity while achieving multiple performance improvements
Solution Approach 2:
The patent introduces electrostatic elements as intermediary components between the conventional lens and the specimen. These intermediaries generate corrective electric fields that modify the charged particle trajectories, enabling improved probe current and opening angles without fundamentally redesigning the entire lens system
3Measurement precision
If higher opening angles are used to improve resolution, then more aberrations are generated, but the patent uses electrostatic elements to correct these aberrations
Solution Approach 1:
The electrostatic elements are positioned to provide preliminary aberration correction before the charged particles reach the focal plane. By applying corrective electric fields in advance, the system pre-compensates for the aberrations that will be generated at higher opening angles, enabling resolution improvement without the usual aberration penalties
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 effectively improves the resolution and probe current of charged particle microscope systems by reducing aberrations, allowing for higher opening angles and enhanced imaging capabilities.
Implementation Method 1
a plurality of electrostatic elements configured to deflect an incident charged particle beam along an α-shaped path
Implementation Method 2
a deflector assembly with a corrector electrostatic prism... configured to at least partially correct an axial chromatic aberration in the charged particle beam
Data Source
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AI summary
Aberration correction systems and charged particle microscope systems including the same. An apparatus can include a plurality of electrostatic multipole elements configured to at least partially correct an axial chromatic aberration of the charged particle beam. The apparatus additionally includes a deflector assembly with a corrector electrostatic prism. The corrector electrostatic prism can include a first corrector prism electrode and a second corrector prism electrode that define an electrode gap therebetween and a deflector optical axis extends within the electrode gap. The plurality of electrostatic multipole elements can include a first hexapole-generating element, a second hexapole-generating element, a third hexapole-generating element, and/or a fourth hexapole-generating element. In some examples, the second hexapole-generating element is positioned proximate to a midpoint of the deflector optical axis. In some examples, each of the second hexapole-generating element and the third hexapole-generating element is positioned at least partially within the corrector electrostatic prism.