Multi-Beam STEM Detection Layout for Higher Throughput Imaging
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Solution Overview
Problem
Scanning Transmission Electron Microscopy (STEM) suffers from sub-optimal throughput due to limited probe/input beam current and Field of View (FoV) limitations caused by lens aberrations and off-axial aberrations, hindering its adoption in high-resolution imaging applications.
Innovation Solution
A Scanning Transmission Charged Particle Microscope (STCPM) is configured to produce multiple charged particle beams that concurrently irradiate different regions of the specimen, with a detector placed between the Back Focal Plane and Imaging Plane to detect and separate the beams' barycenters, enabling enhanced throughput and Field of View through parallel processing and Integrated Differential Phase Contrast (iDPC) imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single probe beam is used in STEM, then imaging resolution can be maintained, but throughput is limited due to sequential scanning requirements
Solution Approach 1:
The single probe beam is segmented into multiple parallel probe beams that can simultaneously illuminate different regions of the specimen. This segmentation enables parallel acquisition of multiple regions, dramatically increasing throughput while maintaining the resolution capabilities of individual probes through controlled beam separation and independent detection
Solution Approach 2:
The system transitions from single-point sequential scanning to multi-point parallel scanning by introducing spatial dimensionality through multiple beams. The beams are arranged in specific patterns (e.g., arrays or grids) that cover multiple regions simultaneously, adding a spatial parallelism dimension to the traditionally sequential process
2Area of stationary object
If lens aberrations are corrected to expand Field of View, then imaging coverage increases, but off-axial aberrations limit the effective FoV
Solution Approach 1:
The Field of View is segmented into multiple smaller regions, each illuminated by a dedicated probe beam positioned on or near the optical axis. By dividing the total FoV into discrete zones and assigning separate beams to each zone, the system avoids off-axial aberrations that would affect a single large FoV, effectively expanding the total usable imaging area
Solution Approach 2:
Each probe beam is optimized for its specific local region, with beam parameters (current, focus, convergence angle) independently adjusted to match the local specimen characteristics and detection requirements. This local optimization ensures high image quality in each region while collectively covering a expanded FoV
3Productivity
If probe beam current is increased to improve signal strength, then imaging speed increases, but beam damage to the specimen increases
Solution Approach 1:
The total beam current required for high-speed imaging is segmented and distributed across multiple probe beams. Each beam operates at a lower current that minimizes specimen damage, while the collective signal from all beams provides sufficient signal strength for high-speed imaging, effectively dividing the harmful current load while maintaining productivity
Solution Approach 2:
Multiple low-current probe beams are merged in the detection system to achieve the equivalent signal strength of a single high-current beam. The detector integrates signals from all beams simultaneously, providing high signal-to-noise ratio and fast imaging capability without subjecting any single specimen region to damaging current levels
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 increases the cumulative Field of View and throughput by allowing simultaneous detection and separation of multiple beam signals, overcoming the limitations of conventional STEM techniques and improving imaging capabilities.
Implementation Method 1
a plurality of charged particle beams are directed onto respective, different regions of a specimen
Implementation Method 2
an imaging system to focus the plurality of charged particle beams onto a detector
Implementation Method 3
a detector, for detecting said plurality of charged particle beams after passing through a sample, is disposed in a detector plane intermediate between a Back Focal Plane (BFP) and an Imaging Plane (IP) of said imaging system, wherein said detector plane is at a location sufficient to provide determination and detection of a barycenter of each of said plurality of charged particle beams
Data Source
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AI summary
Techniques for multi-beam scanning transmission charged particle microscopy are disclosed herein. An example apparatus at least includes a charged particle beam column to produce a plurality of charged particle beams and irradiate a specimen with each of the plurality of charged particle beams, and an imaging system to collect charged particles of each of the charged particle beams of the plurality of charged particle beams that traverse the specimen during said irradiation, and to direct each charged particle beam of the plurality of the charged particle beams after traversing the sample onto a detector, where each charged particle beam includes a barycenter, and where the detector is disposed in an intermediate location between a back focal plane and an imaging plane of the imaging system.