Immersion Gun Electron Beam Column Mixed Field Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electrostatic electron guns suffer from large spherical and chromatic aberration coefficients due to long working distances, which degrade the resolution of electron beam probes, and Coulomb interactions at low beam currents limit resolution further.
Innovation Solution
An electrostatic-magnetic mixed electron gun is developed, featuring a magnetic lens with pole pieces and a winding coil, allowing for three operational modes: e-gun, mag-gun, and mixed gun, with a vacuum tube separating the electron gun from the magnetic lens, enabling improved resolution and throughput by reducing aberrations and electron interactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an electrostatic electron gun is used with a long working distance, then the device complexity is reduced and ease of manufacture is improved, but the spherical and chromatic aberration coefficients increase, degrading the resolution of the electron beam probe
Solution Approach 1:
The patent combines electrostatic and magnetic fields within the electron gun to form a mixed electrostatic-magnetic field. This merging of two different field types allows the system to achieve short working distance characteristics (reducing aberrations) while maintaining the structural simplicity and manufacturing advantages of electrostatic guns. The magnetic lens component is integrated into the existing electrostatic gun architecture.
Solution Approach 2:
The electron gun employs a composite field structure combining electrostatic and magnetic components. The electrostatic field provides the basic electron acceleration and control, while the magnetic field component (through pole pieces and winding coil) provides additional focusing capability. This composite approach allows the system to overcome the limitations of pure electrostatic designs.
2Manufacturing precision
If the working distance of the electron gun is reduced to decrease aberration coefficients, then the resolution is improved, but the device complexity increases due to additional magnetic components
Solution Approach 1:
The patent merges electrostatic and magnetic lens functions into a single integrated electron gun assembly. The magnetic pole pieces and winding coil are incorporated within the existing electrostatic gun structure, allowing the combination of short working distance benefits with manageable device complexity. The unified design avoids the need for separate electrostatic and magnetic gun systems.
3Manufacturing precision
If a magnetic lens is added to form a mixed electrostatic-magnetic gun, then the spherical and chromatic aberration coefficients are reduced, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The magnetic lens components (pole pieces and winding coil) are integrated within the existing electrostatic gun housing and alignment structures. This merging approach allows the magnetic components to be positioned and aligned using the same manufacturing fixtures and procedures already established for electrostatic guns, thereby minimizing the increase in manufacturing difficulty.
4Productivity
If the beam aperture size is increased to allow higher beam current, then the throughput is improved, but the resolution is degraded due to increased Coulomb interactions between electrons
Solution Approach 1:
The patent changes the fundamental parameter of the electron gun from purely electrostatic to a mixed electrostatic-magnetic field configuration. This parameter change fundamentally alters the electron trajectory and distribution, reducing Coulomb interactions between electrons in the beam. As a result, the system can maintain high resolution even at higher beam currents, effectively resolving the trade-off between throughput and resolution.
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
The mixed gun mode achieves higher resolution and throughput by minimizing aberrations and electron interactions, with the e-gun mode optimizing low beam currents and the mag-gun mode handling high beam currents effectively, while maintaining a constant beam limiting aperture size.
Implementation Method 1
A magnetic lens is formed by pole pieces with a winding coil disposed between the magnetic pole pieces. The magnetic lens forms a rotationally symmetrical magnetic field in a gap formed in the pole pieces.
Implementation Method 2
The magnetic field forms the magnetic lens and focuses the electrons emitted from the emitter.
Implementation Method 3
A vacuum tube separates the electron gun from the magnetic lens. The electron gun is sealed in a vacuum by the vacuum tube and the magnetic lens is shielded in air.
Data Source
AI summary
An electron gun of the type having an electron emitter for emitting electrons, including an electrostatic lens and a magnetic lens formed by pole pieces with a winding coil disposed between the magnetic pole pieces. The magnetic lens forms a rotationally symmetrical magnetic field in a gap formed by the pole pieces. The magnetic field forms the magnetic lens and focuses the electrons emitted from the emitter. A vacuum tube separates the electron gun from the magnetic lens. The electron gun is sealed in a vacuum by the vacuum tube and the magnetic lens is shielded in air.