Charged Particle Beam Axial Alignment via Multi-Depth Image Analysis

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Solution Overview

Problem

Current charged particle beam axial alignment methods are inefficient and lack accuracy due to unclear objective wobbling images, requiring skilled operators and lengthy adjustment processes to align the electron beam axis with the objective lens.

Innovation Solution

A charged particle beam axial alignment device that sets the magnetic field strength of the objective lens to two different values, generates scanned images at each strength, and uses image processing to specify the positional relationship between these images, allowing for precise alignment by canceling rotation differences and adjusting the deflector to align the beam axis with the optical axis.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the objective lens strength is changed during beam scanning, then the beam can be focused at different depths, but the beam position rotates on the sample causing alignment difficulty

Engineering Contradiction:

Improvedepth focusing capabilityVSAvoidalignment accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The system captures images at multiple focal depths, detects the rotated beam position through image analysis, and feeds back this information to the deflector control to calculate and apply the necessary correction angles, achieving automated alignment compensation

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The manual mechanical adjustment of the deflector is replaced by an automated control system that uses image processing and computational algorithms to determine and apply the correct deflection angles for beam alignment

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If manual adjustment of the outlet beam deflector is performed, then the beam axis can be aligned with the objective lens, but the process requires high operator skill and extensive time

Engineering Contradiction:

Improvealignment accuracyVSAvoidalignment time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The system performs self-alignment by automatically capturing images, analyzing beam position through image processing, calculating required deflection corrections, and adjusting the deflector without human intervention, making the alignment process autonomous

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

Image processing algorithms serve as an intermediary between the optical system and the deflector control, translating visual beam position information into precise deflection correction commands automatically

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of operation

If the objective wobbling image is used for alignment, then the beam position can be observed, but the image is unclear making rotational center specification difficult

Engineering Contradiction:

Improvealignment operationVSAvoidrotational center detection accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The system performs preliminary image capture at multiple focal depths before final alignment, using these preliminary images to detect the rotational center and calculate correction angles in advance

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system transitions from observing a single unclear two-dimensional wobbling image to capturing multiple clear images at different focal depths, using the third dimension (depth of field) to resolve the ambiguity and clearly identify the rotational center

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 method enables high-accuracy and efficient alignment of the charged particle beam axis, reducing the time and skill required for alignment, ensuring precise alignment regardless of operator expertise.

Implementation Method 1

converges a charged particle beam by a magnetic field of an objective lens

Methodology Applied

Scientific EffectMagnetic field: Magnetic Field

Implementation Method 2

deflects the charged particle beam by a deflector

Methodology Applied

Scientific EffectBeam deflection: Lorentz Force

Data Source

PatentUS10903038B2Charged particle beam axial alignment device, charged particle beam irradiation device and charged particle beam axial alignment method

Publication Date: 2021.01.26 SHIMADZU CORP

AI summary

With strength of an objective lens set to first strength, a first scanned image of a sample is produced. The strength of the objective lens is set to second strength. A rotation amount difference of a charged particle beam between the case where the strength is set to the first strength and the case where the strength is set to the second strength is specified. At the second strength, with a scanner controlled such that the rotation for canceling the rotation amount difference is supplied to the charged particle beam, a second scanned image of the sample is produced. Based on a relative positional relationship between the first and second scanned images, a deflector is controlled such that positions of the first and second scanned images coincide with each other.