Electron Microscope Pulsed Beam Detection Timing

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Solution Overview

Problem

Conventional scanning electron microscopes face challenges in observing insulator or insulator-conductor samples due to image disturbances caused by electrical charging, leading to weakened contrast and superimposed unnecessary information, especially when trying to analyze the internal structure and interface of laminate samples.

Innovation Solution

The method involves controlling the detection timing and time-domain of secondary electron signals during pulsed electron beam irradiation, selecting specific conditions for irradiation and detection, and synchronizing detection with different intermittent conditions to isolate necessary sample information, allowing for improved image quality and selectivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If pulsed electron beam irradiation is used to reduce electrical charging effects, then image disturbance is reduced, but secondary electron signals from different time-domains are integrated causing weakened contrast and superimposed unnecessary information

Engineering Contradiction:

Improveimage qualityVSAvoidsample information selectivity

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

The patent segments the continuous detection process into distinct time-domain windows corresponding to different pulsed electron beam irradiation cycles. By detecting secondary electron signals only during specific time-domains (e.g., during or immediately after electron beam irradiation), the method isolates relevant sample information from unnecessary background signals, thereby maintaining high image quality while preserving information selectivity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent employs periodic pulsed electron beam irradiation combined with periodic signal detection at synchronized time-domains. This periodic action allows the system to repeatedly capture signals at optimal moments in each irradiation cycle, enabling selective extraction of sample information while filtering out charging-related disturbances and unnecessary background signals

Inventive Principle:

Principle #19Periodic action

2Quantity of substance

If all secondary electron signals during irradiation are detected, then signal intensity is increased, but contrast is weakened due to integration of signals without necessary sample information

Engineering Contradiction:

Improvesignal intensityVSAvoidimage contrast

Core Design Contradiction:

Quantity of substanceVSMeasurement precision

Solution Approach 1:

The patent extracts only the relevant portion of secondary electron signals by detecting them within specific time-domains synchronized with the pulsed electron beam irradiation. This extraction method captures sufficient signal intensity for good image quality while excluding signals that do not contain necessary sample information, thereby maintaining both signal strength and image contrast

Inventive Principle:

Principle #2Taking out (Extraction)

3Loss of information

If voltage contrast from electrical charging is extracted to observe embedded structure, then internal structure information is obtained, but image disturbance occurs due to superimposition of voltage contrast on shape contrast

Engineering Contradiction:

Improveembedded structure informationVSAvoidimage disturbance

Core Design Contradiction:

Loss of informationVSObject-affected harmful factors

Solution Approach 1:

The patent uses dynamic time-domain selection to detect secondary electron signals at different phases of the pulsed irradiation cycle. By adjusting the detection timing and duration dynamically, the system can emphasize either shape contrast or voltage contrast depending on the observation goal, reducing harmful superimposition while preserving useful embedded structure information

Inventive Principle:

Principle #15Dynamics

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-quality image capture and selective analysis of sample information, effectively reducing image disturbances and enhancing the visualization of embedded structures and interfaces by selectively detecting secondary electron signals in specific time-domains and conditions.

Implementation Method 1

an electron beam which has been accelerated by a voltage applied to an electron source

Methodology Applied

Scientific EffectElectron acceleration:

Implementation Method 2

focuses an electron beam by an electron lens

Methodology Applied

Scientific EffectElectron lens focusing:

Implementation Method 3

scans the focused electron beam (a primary electron) on a sample by a reflector

Methodology Applied

Scientific EffectElectromagnetic deflection:

Implementation Method 4

An electron (a secondary electron) which has been emitted from the sample by being irradiated with the primary electron

Methodology Applied

Scientific EffectSecondary electron emission:

Implementation Method 5

A secondary electron signal is detected in synchronization with a scanning signal

Methodology Applied

Scientific EffectElectron detection:

Data Source

PatentUS8907279B2Electron microscope and image capturing method using electron beam

Publication Date: 2014.12.09 HITACHI HIGH TECH CORP

AI summary

The present invention is characterized by an electron microscope which intermittently applies an electron beam to a sample and detects a secondary electron signal, wherein an arbitrarily defined detection time (T2) shorter than the pulse width (Tp) of the applied electron beam is selected, and a secondary electron image is formed using the secondary electron signal acquired during the detection time. Consequently, it is possible to reflect necessary sample information including the internal structure and laminated interface of the sample in the contrast of an image and prevent unnecessary information from being superimposed on the image, thereby making it possible to obtain the secondary electron image with improved sample information selectivity and image quality.