Electron Beam Potential Control for Small Spot Imaging
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Solution Overview
Problem
Conventional electron beam systems face limitations in achieving optimal focusing and resolution due to the high potential required in the beam tube, which can result in unsuitable images for certain applications, necessitating a switch to an operating mode with a high detected signal.
Innovation Solution
A method is proposed where the potential supplied to the electron beam source, beam tube, and object are set such that the beam tube potential is greater than the object potential, allowing for deceleration of electrons and focusing without a magnetic lens, with adjustments made to the current supplied to the magnetic lens to maintain focusing while reducing the beam tube potential, and potentially switching to an operating mode with a higher detected signal by modifying these potentials and currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the potential supplied to the beam tube is increased to accelerate electrons, then the electrons reach the object quicker and experience less electrostatic repulsion, but the spot size increases and resolution decreases
Solution Approach 1:
The patent changes the operating parameters by setting the beam tube potential below the object potential, creating a decelerating field that compensates for electrostatic repulsion effects and maintains small spot size while still achieving adequate electron speed through the potential difference between source and beam tube
Solution Approach 2:
The patent creates different potential conditions in different regions: strong acceleration from source to beam tube entrance, deceleration within the beam tube region to counteract repulsion, and controlled focusing at the object plane, optimizing each region's potential profile for its specific function
2Manufacturing precision
If the potential supplied to the beam tube is reduced to decrease spot size, then the resolution improves, but the electrons take longer to reach the object and experience more electrostatic repulsion
Solution Approach 1:
The patent inverts the conventional parameter relationship by setting beam tube potential below object potential, creating a decelerating field that actually reduces the net repulsion effect while maintaining small spot size, contrary to conventional acceleration approaches
3Manufacturing precision
If high potential is supplied to the beam tube to achieve small spot size, then resolution is improved, but the detected signal is insufficient for certain applications
Solution Approach 1:
The patent changes the potential profile to allow operation at lower beam tube potentials that maintain small spot size while increasing electron transmission and detected signal, enabling dual optimization of resolution and signal strength
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 enables continued focusing with reduced beam tube potential and increased magnetic lens current, potentially improving image sharpness and signal detection, allowing for better resolution and image quality in electron-microscopic images.
Implementation Method 1
an electrostatic field which already deflects electrons of an electron beam by the electrostatic interaction therewith and which acts on the electrons like a focusing lens is prevalent between the beam tube and the object
Implementation Method 2
an electrostatic field which already deflects electrons of an electron beam by the electrostatic interaction therewith
Implementation Method 3
focusing the beam on the object by modifying at least one current which is supplied to at least one magnetic lens such as an objective lens
Data Source
AI summary
A method for operating an electron beam system comprises setting a first potential supplied to an electron emitter to a first value, a second potential supplied to a beam tube to a second value and a third potential supplied to an object to a third value such that the third potential is greater than the first potential and the second potential is greater than the third potential. The method also comprises focusing a beam of the electron beam system on the object by modifying at least one current supplied to at least one focusing magnetic lens.