Electron Tomography Stage Control for Tilted-Sample Focus Tracking

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Solution Overview

Problem

Existing electron tomography methods are time-consuming due to the need for mechanical translation and refocusing of the electron beam between different features, leading to low sample throughput and inaccurate height information of features extending from the surface.

Innovation Solution

A method and system that maintains electron beam focus while translating the sample in three dimensions, including X, Y, and Z components, allowing for faster data collection and improved height information by adjusting the tilt angle and using a combination of electron beam deflection and mechanical translation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If mechanical translation is used to move the sample between different features, then the electron beam can be directed at different locations, but the refocusing process increases data acquisition time

Engineering Contradiction:

Improvefocus accuracyVSAvoiddata acquisition time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The system pre-calculates and pre-positions the translation stage at the correct Z-height corresponding to the tilted sample surface before data acquisition begins. This preliminary action eliminates the need for time-consuming refocusing operations during the actual tilt series collection, as the beam is already focused at the correct plane when tilting commences

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent replaces the traditional mechanical refocusing process (adjusting focus knobs, moving lenses) with a computational approach. By calculating the Z-translation required to compensate for tilt-induced focus shifts and programming the translation stage to maintain constant focus automatically, the system substitutes manual/mechanical refocusing with automated positional control

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Loss of information

If the sample is tilted to collect tomography data, then three-dimensional structural information can be obtained, but the mechanical translation becomes more complex and time-consuming

Engineering Contradiction:

Improvethree-dimensional structural informationVSAvoidtranslation stage complexity

Core Design Contradiction:

Loss of informationVSDevice complexity

Solution Approach 1:

The system changes the control parameters of the translation stage from simple X-Y positioning to three-dimensional X-Y-Z positioning that accounts for tilt angle. By programming the stage to move in the Z-direction according to the formula Z = X × tan(θ), where θ is the tilt angle, the system simplifies the overall process despite the added dimensional complexity, as this automated calculation replaces complex manual coordination

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If the electron beam is refocused after each mechanical translation, then accurate imaging can be maintained, but sample throughput decreases

Engineering Contradiction:

Improveimaging accuracyVSAvoidsample throughput

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The system establishes continuous useful action by programming the translation stage to automatically maintain focus throughout the entire tilt series acquisition. The Z-position is continuously adjusted based on the current tilt angle and beam position, eliminating interruptions for manual refocusing and maintaining continuous data collection across all features and angles

Inventive Principle:

Principle #20Continuity of useful action

Solution Approach 2:

The system implements feedback control where the actual tilt angle and beam position are continuously monitored, and the translation stage Z-position is automatically adjusted in response to these measurements. This closed-loop feedback ensures the electron beam remains focused on the tilted sample surface without requiring manual intervention

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

This approach reduces data acquisition time by up to 30% and provides more accurate height information of features by minimizing the need for refocusing and optimizing mechanical translations.

Implementation Method 1

electron beam focussing optics with the electron beam source

Methodology Applied

Scientific EffectElectromagnetic focusing: Electromagnetic Induction

Implementation Method 2

translating the sample at a current tilt angle

Methodology Applied

Scientific EffectMechanical translation:

Data Source

PatentUS20250255564A1Tomography stage control

Publication Date: 2025.08.14 FEI CO

AI summary

A method and system for obtaining electron tomography data from a sample includes a) focussing an electron beam at a first location on a surface of the sample, b) tilting the surface of the sample to a tilt angle to the electron beam while maintaining the surface of the sample at the focus of the electron beam, c) detecting the electron beam focussed at the first location on the surface of the sample, d) translating the sample at the tilt angle to move the focus of the electron beam to at least a second location of the surface of the sample, e) detecting the electron beam focussed on at least the second location on the surface of the sample, and repeating steps b) to e) at one or more different tilt angles.