Selectable Coulomb Aperture for E-Beam Resolution
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Solution Overview
Problem
Electron beam systems face resolution degradation due to Coulomb interactions between electrons, which conventional methods like increasing primary beam energy or applying a retarding force complicate the system and are not preferred.
Innovation Solution
A selectable Coulomb aperture is introduced between the electron gun and condenser lens, comprising a non-magnetic conductive plate with variant-sized holes to reduce electron-electron interactions, allowing operators to adjust aperture size based on required beam current, thereby minimizing probe size broadening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If primary beam energy is increased to reduce Coulomb interactions, then resolution is improved, but landing energy increases which is not preferred
Solution Approach 1:
The patent divides the electron beam into multiple smaller beams by introducing an aperture plate with multiple apertures between the electron source and condenser lens. This segmentation reduces the number of electrons in each individual beam, thereby reducing Coulomb interactions and improving spatial resolution without increasing the primary beam energy or landing energy.
2Measurement precision
If a retarding force is applied to reduce Coulomb interactions, then resolution is improved, but the mechanism becomes much more complicated
Solution Approach 1:
The patent extracts the excess electrons from the electron beam by using an aperture plate with multiple apertures. By removing (taking out) a portion of the electrons before they reach the condenser lens, the Coulomb interactions are reduced without requiring complex retarding force mechanisms, thus improving resolution while keeping the system simple.
3Productivity
If beam current is increased for better signal, then productivity is improved, but Coulomb interactions increase broadening the probe size
Solution Approach 1:
The aperture plate with multiple apertures segments the high-current electron beam into multiple lower-current sub-beams. This allows the system to maintain a high total beam current for improved signal and productivity, while each individual sub-beam has reduced electron density, minimizing Coulomb interactions and preventing probe size broadening.
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 design effectively reduces Coulomb interactions, enhancing the spatial resolution of electron beam systems without increasing landing energy or complicating the mechanism, allowing for improved imaging of nanoscale objects.
Implementation Method 1
Coulomb interactions between the electrons within the electron beam illumination system
Data Source
AI summary
A selectable Coulomb aperture in charged particle system comprises a non-magnetic conductive plate with a plurality of holes therein. The plurality of holes has variant sizes or diameters to select different beam currents of primary beam in the charged particle system. The charged particle system may include a charged particle source for emitting a primary beam, a condenser lens for receiving the primary beam and condensing the primary beam, an objective lens for receiving the primary beam and focusing the primary beam on a surface of a specimen. The selectable Coulomb aperture is positioned between the charged particle source and the condenser lens.