Hexapole Aberration Corrector for Three-Lobe Error Correction

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Solution Overview

Problem

Existing aberration correctors for electron microscopes fail to effectively correct three-lobe aberrations, which limit the resolution of electron microscopes.

Innovation Solution

An aberration corrector is designed with a first and second multipole configured to form a hexapole field, and transfer optics including round lenses are placed between them to adjust the slope of the charged particle beam, allowing for the correction of three-lobe aberrations by differing the absolute value of the slope between the first and second multipole.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a conventional aberration corrector with multipoles is used, then general aberration correction is achieved, but three-lobe aberration remains uncorrected

Engineering Contradiction:

ImproveresolutionVSAvoidaberration correction completeness

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The aberration correction system is divided into multiple independent multipole stages (first multipole, second multipole, third multipole) with transfer optics between them. Each multipole stage independently generates and corrects specific aberration components, allowing the three-lobe aberration to be addressed separately from other aberrations through the asymmetric slope configuration in the transfer optics.

Inventive Principle:

Principle #1Segmentation

2Device complexity

If symmetric transfer optics are used between multipoles, then simple optical design is maintained, but three-lobe aberration cannot be corrected

Engineering Contradiction:

Improveoptical design simplicityVSAvoidresolution

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The transfer optics are configured with asymmetric slope values between the first and second multipoles. Specifically, the absolute value of the slope of the charged particle beam passing through the first multipole is made different from the absolute value of the slope passing through the second multipole. This asymmetric configuration enables the transfer optics to differentially correct three-lobe aberration while maintaining a relatively simple overall optical design.

Inventive Principle:

Principle #4Asymmetry

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 configuration enables the effective correction of three-lobe aberrations, improving the overall resolution of electron microscopes by controlling the aberrations generated in each multipole.

Implementation Method 1

a first multipole and a second multipole configured to form a hexapole field

Methodology Applied

Scientific EffectHexapole field: Magnetic Field

Implementation Method 2

a transfer optics including a plurality of round lenses

Methodology Applied

Scientific EffectLens refraction: Lens

Data Source

PatentUS20240006148A1Aberration corrector and electron microscope

Publication Date: 2024.01.04 HITACHI HIGH TECH CORP

AI summary

An aberration corrector includes: a first multipole and a second multipole configured to form a hexapole field; and a transfer optics including a plurality of round lenses. The transfer optics is disposed between the first multipole and the second multipole, and acts on a charged particle beam such that an absolute value of a slope of the charged particle beam passing through the first multipole is different from an absolute value of a slope of the charged particle beam passing through the second multipole.