Charged Particle Beam Apparatus Depth Imaging
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Solution Overview
Problem
Existing charged particle beam apparatuses face challenges in forming SEM images that reflect sample shapes at desired depths without apparatus enlargement, particularly when observing samples with structures in the depth direction, due to the need for multiple signal processing circuits and calibration for wide energy band acquisition.
Innovation Solution
A charged particle beam apparatus is configured with an irradiation optical system, a detection optical system using a detector that converts charged particles into electric signals, and an image processing unit that counts detected particles for each pixel and forms images based on wave height values of electric signal pulses, allowing for single image acquisition and avoidance of apparatus enlargement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a multichannel system is used to acquire BSE of a wide energy band at once, then image acquisition is performed according to the number of arranged detectors, but it requires providing a signal processing circuit for every energy band which requires enlargement of the apparatus
Solution Approach 1:
The patent merges multiple energy band detections into a single detection channel by using a single detector that sequentially measures different energy bands during one image acquisition cycle. This eliminates the need for multiple parallel detection channels and their associated signal processing circuits, thereby avoiding apparatus enlargement while maintaining the capability to acquire wide energy band information.
Solution Approach 2:
The patent introduces dynamic energy band selection during image acquisition, where the energy filter is adjusted to select different energy bands at different time points within a single acquisition cycle. This dynamic approach allows one detector to perform the work of multiple static detectors, achieving wide energy band coverage without increasing apparatus complexity.
2Productivity
If a multichannel system is used to acquire BSE of a wide energy band at once, then image acquisition is performed according to the number of arranged detectors, but it requires calibration or tuning to a plurality of signal processing circuits
Solution Approach 1:
The patent combines multiple energy band measurements into a single detection sequence using one detector and one signal processing circuit. This eliminates the need for calibration and tuning of multiple parallel circuits, as only a single circuit needs to be calibrated. The system sequentially measures different energy bands and processes them through the same calibrated circuit, greatly simplifying operation.
3Productivity
If energy band pass filtering is used to detect signal electrons, then detection is performed by a single image acquisition, but it requires an energy selective detector of electric field shielding type or orbital selection type which complicates the apparatus structure
Solution Approach 1:
The patent changes the detection approach by using an ordinary semiconductor detector and achieving energy band selection through temporal and sequential measurement rather than through complex detector structure. The energy filtering is accomplished by controlling the measurement timing and energy filter settings during the acquisition process, not by the detector's inherent structure, thereby simplifying the apparatus.
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
Enables the formation of SEM images that reflect sample shapes at desired depths with high resolution and contrast, while maintaining apparatus size, by accurately counting and processing signal electrons at each sampling time and integrating multiple frames for improved signal-to-noise ratio.
Implementation Method 1
a detector that detects the charged particles generated from the sample by the irradiation of the charged particle beam and converts them into an electric signal
Data Source
AI summary
In observation of a sample having a structure in its depth direction, a charged particle beam apparatus that can form an SEM image reflecting a sample shape at a desired depth by a single image acquisition while avoiding enlargement of the apparatus is provided. The apparatus has: an irradiation optical system for irradiating and scanning a charged particle beam generated from a charged particle source on the sample; a detection optical system having a detector that detects charged particles generated from the sample by the irradiation of the charged particle beam, and converts them into an electric signal at a predetermined sampling period; and an image processing unit for forming an image based on the electric signal from the detector, in which the image processing unit detects a peak of wave height values for each pixel from the electric signal at each sampling time, and forms the image based on the peak of the detected wave height values.