EBSP Imaging via Energy-Filtered Detection

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Solution Overview

Problem

Conventional Electron Backscattered Pattern (EBSP) imaging techniques face challenges in achieving high-quality images without using high tilt angles greater than 45 degrees, which results in loss of focus and beam displacement due to charging effects and vibrations in non-vertical electron columns.

Innovation Solution

The method employs an energy-filtered signal by using a position-sensitive detector capable of selectively detecting electrons above a predefined threshold, allowing for improved resolution and contrast in EBSP imaging at lower tilt angles, utilizing detectors like Medipix or Timepix, and adjusting beam energy for better signal-to-noise ratio.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If high tilt angles greater than 45 degrees are used for EBSP imaging, then contrast of Kikuchi lines is improved, but beam focus is lost and beam displacement occurs due to charging effects

Engineering Contradiction:

Improvecontrast of Kikuchi linesVSAvoidbeam focus

Core Design Contradiction:

Illumination intensityVSMeasurement precision

Solution Approach 1:

The patent changes the detection parameter by introducing energy filtering of backscattered electrons. By selecting electrons within specific energy ranges (e.g., 5-10 eV above secondary electron cutoff), the method achieves high-contrast Kikuchi patterns at normal incidence angles without the charging effects that plague high-tilt configurations. This parameter change in detection energy resolves the contradiction between contrast and focus.

Inventive Principle:

Principle #35Parameter changes

2Illumination intensity

If high tilt angles are used for EBSP imaging, then contrast of Kikuchi lines is improved, but beam displacement occurs due to vibrations in non-vertical electron columns

Engineering Contradiction:

Improvecontrast of Kikuchi linesVSAvoidbeam position stability

Core Design Contradiction:

Illumination intensityVSManufacturing precision

Solution Approach 1:

Instead of tilting the sample to achieve the desired detection geometry, the patent inverts the approach by keeping the sample at normal incidence and using energy-filtered detection of backscattered electrons. This reversal of the conventional geometry eliminates vibration-induced beam displacement while maintaining high contrast through energy-selective detection.

Inventive Principle:

Principle #13The other way round (Inversion)

3Device complexity

If conventional detectors are used for EBSP imaging, then device complexity is reduced, but image resolution and contrast are insufficient at low tilt angles

Engineering Contradiction:

Improvedetector systemVSAvoidimage resolution

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent makes the detector system multi-functional by using an energy-filtering capability that serves both to eliminate charging effects and to enhance Kikuchi line contrast. The same energy-filtering mechanism that solves the charging problem also provides the resolution enhancement needed for low-tilt imaging, reducing the need for separate specialized components.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 enables high-resolution, high-contrast EBSP imaging at lower tilt angles, reducing beam damage and improving analysis of thin films and fragile samples, while maintaining image quality and reducing distortions.

Implementation Method 1

When an electron beam impinges on ('hits') a sample, backscattered electrons (BSEs) emerge from the sample

Methodology Applied

Scientific EffectElectron backscattering:

Implementation Method 2

The position sensitive detector is equipped to selectively detect electrons with an energy above a predefined threshold

Methodology Applied

Scientific EffectEnergy filtering: Filter (physical)

Implementation Method 3

the BSEs do not emerge from the sample in all directions with the same intensity/probability. Among other effects, in certain directions the intensity is larger due to preferential reflection on the crystal lattice, and thereby so-called Kikuchi lines are formed on the detector

Methodology Applied

Scientific EffectElectron diffraction: Diffraction

Implementation Method 4

The direction in which the Kikuchi-lines are formed is a function of the direction of the impinging beam and the crystallographic axes and the type of unit cell

Methodology Applied

Scientific EffectKikuchi line formation:

Data Source

PatentUS9618463B2Method of acquiring EBSP patterns

Publication Date: 2017.04.11 FEI CO

AI summary

The invention relates to a method of acquiring an Energy Backscattering Pattern image of a sample in a charged particle apparatus, the sample showing a flat surface, the charged particle apparatus equipped with an electron column for producing a finely focused electron beam, a position sensitive detector for detecting EBSP patterns, and a sample holder for holding and positioning the sample, the method comprising the steps of:Positioning the sample with respect to the electron beam,Directing the electron beam to an impact point on the sample, thereby causing backscattered electrons to irradiate the detector, andAcquiring the signal from the detector while the beam is kept stationary,in whichThe detector is equipped to selectively detect electrons with an energy above a predefined threshold, andThe signal of the electrons with an energy above said threshold is used to form an EBSP image.