Charged Particle Beam Detection for Backscatter-Secondary Separation
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Solution Overview
Problem
Existing charged particle beam devices struggle to detect signal charged particles in a wide range of elevation angles and accurately distinguish between backscattered and secondary charged particles, especially for structures with low aspect ratios and non-axisymmetric signal electron distributions.
Innovation Solution
A charged particle beam device comprising a first detector for secondary or backscattered charged particles and a second detector for tertiary charged particles, where the observation image is generated by subtracting part of the second detection signal from the first detection signal, or vice versa, to effectively distinguish between backscattered and secondary charged particles regardless of their distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single detector is used to detect signal electrons, then the device complexity is reduced, but the measurement precision deteriorates due to inability to distinguish between backscattered and secondary electrons
Solution Approach 1:
The detection system is segmented into multiple detectors: a first detector for detecting backscattered electrons and a second detector for detecting secondary electrons. This segmentation allows each detector to specialize in detecting specific electron types, thereby improving measurement precision while maintaining manageable device complexity through functional division.
Solution Approach 2:
An energy filter is introduced as an intermediary component between the sample and the detectors. The energy filter selectively transmits electrons based on their energy levels, enabling the first detector to receive primarily backscattered electrons (higher energy) and the second detector to receive primarily secondary electrons (lower energy), thus improving discrimination accuracy.
2Measurement precision
If detectors are positioned to detect signal electrons at specific elevation angles, then the measurement precision for certain structures is improved, but the adaptability to structures with varying aspect ratios deteriorates
Solution Approach 1:
The detection system is designed with multi-functional capability to handle various structure types. By combining multiple detectors positioned at different elevation angles and using energy filtering, the system can adaptively optimize detection for both high aspect ratio structures (using larger elevation angles) and low aspect ratio structures (using smaller elevation angles), thereby achieving universality across different sample geometries.
Solution Approach 2:
The system dynamically adjusts detection parameters based on sample characteristics. The energy filter and detector positioning enable the system to optimize detection conditions in real-time, switching between different elevation angle configurations and energy thresholds depending on whether the sample has high or low aspect ratio features, thus maintaining measurement precision across varying structures.
3Measurement precision
If the energy filter is set to selectively transmit backscattered electrons, then the measurement precision for depth information is improved, but the quantity of detected signal electrons deteriorates due to exclusion of secondary electrons
Solution Approach 1:
The electron detection is segmented into two separate detection channels: one channel (first detector) optimized for detecting backscattered electrons with higher energy, and another channel (second detector) optimized for detecting secondary electrons with lower energy. This segmentation allows each detector to capture its target electron type efficiently without the other interfering, thereby maintaining total signal quantity while improving discrimination precision.
Solution Approach 2:
The system merges the detection outputs from the first detector (backscattered electrons) and the second detector (secondary electrons) to form a comprehensive signal. By combining these separate detection channels, the system recovers the total signal electron quantity that would be lost if only one electron type were detected, while simultaneously maintaining high precision through energy-based discrimination.
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
The device enables detection of signal charged particles across a wide range of elevation angles and accurate discrimination between backscattered and secondary charged particles, improving measurement accuracy for structures with varying aspect ratios.
Implementation Method 1
a first detector that detects secondary charged particles or backscattered charged particles
Implementation Method 2
a second detector that detects tertiary charged particles generated from the first detector
Implementation Method 3
generates an observation image of the sample using a signal value obtained by subtracting at least a part of a second detection signal output by the second detector from a first detection signal output by the first detector
Data Source
AI summary
Provided is a charged particle beam device capable of detecting signal charged particles in a wide range of elevation angles from a large elevation angle to a small elevation angle and distinguishing detection signals between backscattered charged particles and secondary charged particles regardless of distribution of the signal charged particles. The charged particle beam device according to the disclosure includes a first detector that detects the secondary charged particles or the backscattered charged particles and a second detector that detects tertiary charged particles generated from the first detector, and generates an observation image of a sample using a signal value obtained by subtracting at least a part of a second detection signal output by the second detector from a first detection signal output by the first detector, or subtracting at least a part of the first detection signal from the second detection signal.