Cold Field Emitter Image Stabilization via Current Fluctuation Feedback

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Solution Overview

Problem

Cold field emitters in particle beam systems, such as electron beam microscopes, exhibit temporal fluctuations in electron emission current, leading to undesirable light or dark stripes in images, compromising image quality.

Innovation Solution

A method and device that detect abrupt changes in the emission current of the particle beam generator, allowing the beam to be returned to the location of the change, enabling re-scanning and correction of image information, thereby maintaining consistent image quality by adjusting the emission current to a desired value.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a cold field emitter is used as a particle beam generator, then high directional beam value and narrow beam energy width are achieved, but temporal fluctuations in electron emission current occur causing light or dark stripes in images

Engineering Contradiction:
Improvebeam diameter precisionVSAvoidemission current stability
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The system continuously monitors the emission current of the cold field emitter and automatically adjusts parameters to compensate for temporal fluctuations. When current variations are detected, the system modifies the particle beam parameters or re-scans affected areas to maintain consistent image quality, eliminating the light or dark stripe artifacts.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The invention dynamically changes operational parameters such as emission current, beam energy, or scanning speed in response to detected fluctuations. By adjusting these parameters in real-time, the system compensates for the inherent instability of cold field emitters while preserving their advantage of producing narrow beam diameters for high-resolution imaging.

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If the particle beam is returned to the location of parameter change for re-scanning, then image quality is improved by correcting erroneous information, but recording time is increased

Engineering Contradiction:
Improveimage qualityVSAvoidrecording time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

Instead of re-scanning the entire image area, the system performs partial re-scanning only of the specific regions where parameter changes were detected. This selective approach corrects erroneous image information at affected locations while minimizing the additional recording time required, thus balancing image quality improvement with time efficiency.

Inventive Principle:
Principle #16Partial or excessive action

3Reliability

If emission current is adjusted to maintain stable image generation, then image artifacts are avoided, but system complexity increases due to monitoring and adjustment mechanisms

Engineering Contradiction:
Improveimage consistencyVSAvoidcontrol system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The system incorporates automatic self-monitoring and self-adjustment capabilities that operate autonomously without requiring external intervention. The emission current monitoring and adjustment mechanisms function automatically, detecting fluctuations and correcting image quality issues in real-time, thereby maintaining reliable and consistent image generation while managing system complexity through automated control.

Inventive Principle:
Principle #25Self-service

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 approach ensures stable image generation with minimal impact on recording time, avoiding image artifacts and maintaining adequate brightness and contrast, thus ensuring good image quality.

Implementation Method 1

Cold field emitters have a high directional beam value and a narrow beam energy width. They are therefore particularly suitable for achieving very small electron beam diameters

Methodology Applied
Scientific EffectField emission:

Implementation Method 2

an objective lens for focusing the electron beam on an object

Methodology Applied
Scientific EffectElectromagnetic focusing: Electromagnetic Induction

Implementation Method 3

The electron beam is guided in a grid pattern over the surface of the object to be examined by means of a deflection device

Methodology Applied
Scientific EffectElectromagnetic deflection: Lorentz Force

Implementation Method 4

at least one detector for detecting electrons scattered on the object or electrons emitted by the object

Methodology Applied
Scientific EffectElectron detection: Photoelectric Effect

Data Source

PatentEP2041771B1Method and device for producing an image
Publication Date: 2012.02.01 CARL ZEISS NTS GMBH
  • EP2041771B1 patent drawingFigure 1
  • EP2041771B1 patent drawingFigure 2
  • EP2041771B1 patent drawingFigure 3a~3c

AI summary

The invention relates to a method and to a device (1) for producing an image of an object (5) by means of a particle beam. According to the method and in the device (1), the particle beam is scanned by the object (5). The aim of the invention is to provide a method and a device for producing an image of an object (5) by means of a particle beam that can be used with a cold field emitter (2) in such a manner that a good image quality is constantly ensured. Said aim is achieved by virtue of the fact that, according to the invention, when a radiation parameter is altered, the object (5) is rescanned preferably with the corrected parameter. The inventive device (1) comprises the corresponding means (4, 6, 7) therefor.