Particle Beam Column With Multi-Aperture Current Range Control
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Solution Overview
Problem
Conventional particle beam columns are limited by the anode stop, restricting the maximum current strength and dynamic range of the particle beam, leading to prolonged dwell times for image recording.
Innovation Solution
A particle beam column design featuring a first lens to variably set the divergence angle of the beam, a multi-aperture stop with differently sized apertures, and a deflection system to selectively direct the beam through these apertures, combined with a magnetic lens configuration that allows for variable current strength and dynamic range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a conventional anode stop is used to accelerate particles, then the particle beam can be accelerated to predetermined energy, but the current strength of the particle beam is limited
Solution Approach 1:
The aperture stop is divided into multiple independently controllable aperture elements with different aperture sizes. Each aperture element can be selectively activated to pass different amounts of particle beam, thereby enabling variable current strength without being limited by a single fixed aperture size. This segmentation allows the system to achieve both high current strength (when needed) and fast imaging (when high current is available).
Solution Approach 2:
The aperture elements are made dynamically controllable through individual actuators that can adjust the opening state of each aperture element independently. This dynamic control allows the system to adapt the beam current strength in real-time based on imaging requirements, resolving the contradiction between needing high current for speed and being able to use lower current when sufficient signal is obtained quickly.
2Productivity
If the current strength of the particle beam is increased to reduce dwell time, then image recording speed improves, but the dynamic range of current strength adjustment is reduced
Solution Approach 1:
Different aperture elements have different aperture sizes optimized for different current strength requirements. Smaller aperture elements provide precise low-current control for high-resolution imaging, while larger aperture elements enable high-current operation for fast imaging. This local differentiation of aperture qualities across the stop structure enables both high productivity and high adaptability simultaneously.
Solution Approach 2:
The system changes the effective aperture parameter by selectively activating different aperture elements or combinations thereof. This allows continuous or discrete adjustment of the beam current strength over a wide dynamic range, enabling the system to adapt to different imaging conditions while maintaining high recording speed when appropriate current levels are achieved.
3Power
If a single aperture stop is used, then the device structure remains simple, but the maximum current strength and dynamic range are limited
Solution Approach 1:
The aperture stop is segmented into multiple aperture elements that can be independently controlled. While this increases structural complexity compared to a single aperture, the segmentation enables significantly higher maximum current strength and extended dynamic range. The modular nature of the segmentation allows for scalable implementation where the complexity increase is justified by the substantial performance gains in current strength and adaptability.
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
Enhances the maximum current strength and dynamic range of the particle beam, enabling more efficient and flexible operation of scanning electron microscopes and focused ion beam systems.
Implementation Method 1
a first lens, which is configured to variably set a divergence angle of the particle beam upstream of the first stop
Implementation Method 2
a first lens comprising a magnetic lens, which is configured to generate, upstream of the first stop, a magnetic field for focusing the particle beam
Implementation Method 3
a deflection system configured to selectively deflect the particle beam downstream of the first stop onto one of the apertures of the multi-aperture stop
Implementation Method 4
an objective lens which is arranged downstream of the multi-aperture stop and is configured to focus the particle beam passing through the selected aperture of the multi-aperture stop
Implementation Method 5
an objective lens which is arranged downstream of the multi-aperture stop and is configured to focus the particle beam
Data Source
AI summary
A particle beam column generates a particle beam of charged particles, for example electrons or ions, and direct it onto a sample. The particle beam column comprises a multi-aperture stop and a deflection system for selectively steering the particle beam through one of a plurality of apertures provided in the multi-aperture stop. The apertures have different sizes in order to limit the current strength of the particle beam to different values. The particle beam column furthermore comprises a lens for changing the divergence angle of the particle beam upstream of a first stop. The lens can comprise a magnetic lens, which comprises a magnetic core with a plurality of parts, which are electrically insulated from one another and can have substantially different electrical potentials during operation. Some of the parts of the magnetic core can have the same electrical potential as the first stop during operation.