Charged Particle Beam Control for High-Frequency Beam Diameter Measurement

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing charged particle beam apparatuses, such as scanning electron microscopes, struggle to accurately measure the variation of the electron beam diameter, particularly at high frequencies due to electrical noise, which affects image quality and resolution.

Innovation Solution

A charged particle beam apparatus equipped with a processor system that acquires time-series changes in secondary electron detection-related quantities and beam diameter variations by controlling deflectors or scanning coils, using fast Fourier transforms to analyze frequency spectra and identify noise sources.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If existing measurement techniques are used to measure beam diameter variation, then measurement capability is provided, but high frequency noise measurement is not achievable

Engineering Contradiction:

Improvebeam diameter variation measurementVSAvoidhigh frequency measurement accuracy

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent implements dynamic measurement by continuously scanning the electron beam across the sample at high speed and capturing time-series secondary electron signals. This dynamic approach enables the system to measure beam diameter variations at high frequencies (up to several MHz) by converting spatial information into temporal information through rapid scanning, thereby achieving reliable high-frequency noise measurement that static methods cannot provide.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent replaces complex mechanical adjustment systems with signal processing methods. Instead of using mechanical means to physically measure beam diameter at different frequencies, the system uses secondary electron signal detection combined with Fast Fourier Transform (FFT) analysis to extract beam diameter variation information in the frequency domain, eliminating the need for mechanical measurement apparatus and enabling high-frequency measurement capabilities.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Productivity

If electrical noise is present in the system, then operational functionality is maintained, but beam diameter measurement accuracy deteriorates

Engineering Contradiction:

Improveoperational continuityVSAvoidbeam diameter measurement accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent converts the harmful effect of electrical noise into a useful measurement signal. By deliberately irradiating a sample with known characteristics (such as a grid pattern or edge structure) and detecting the resulting secondary electron signals, the system measures beam diameter variations that include noise components. The FFT analysis then separates the noise frequency components from the signal, allowing the system to characterize and ultimately compensate for noise effects, turning noise from a detrimental factor into a measurable parameter for system characterization.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent implements feedback-based noise compensation by measuring beam diameter variations under actual operating conditions including electrical noise, analyzing the noise characteristics through FFT, and using this information to adjust measurement parameters or apply correction algorithms. This feedback loop allows the system to maintain measurement accuracy despite the presence of electrical noise by continuously adapting to the actual noise environment.

Inventive Principle:

Principle #23Feedback

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 precise measurement of electron beam diameter variations, allowing for improved image resolution and identification of noise sources, even at high frequencies, without requiring SEM simulation.

Implementation Method 1

a charged particle source generating a charged particle beam

Methodology Applied

Scientific EffectElectron beam: Electron Beam

Implementation Method 2

a deflector deflecting the charged particle beam

Methodology Applied

Scientific EffectElectromagnetic deflection: Lorentz Force

Implementation Method 3

a detector detecting secondary electrons emitted from an irradiation target in response to the irradiation with the charged particle beam

Methodology Applied

Scientific EffectSecondary electron emission: Photoelectric Effect

Data Source

PatentUS12456598B2Charged particle beam apparatus

Publication Date: 2025.10.28 HITACHI HIGH TECH CORP

AI summary

The charged particle beam apparatus includes a charged particle source generating a charged particle beam, a deflector deflecting the charged particle beam, a detector detecting secondary electrons emitted from an irradiation target in response to irradiation with the charged particle beam, and a processor system. The processor system (A) acquires a first time-series change in secondary electron detection-related quantity by repeatedly performing the following (A1) and (A2), (A1) directly or indirectly, maintains or changes the control amount applied to the deflector to a first control amount, and (A2) acquires the secondary electron detection-related quantity based on an output from the detector, and (B) acquires a time-series change in variation of the beam diameter of the charged particle beam based on the first time-series change.