Ion Milling System Magnetic Shield for Electron Beam Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The ion milling system with a Penning discharge type ion gun faces challenges due to a leakage magnetic field from the permanent magnet, which causes curvature of the electron beam during electron microscope observation, especially when observing microscopic regions.
Innovation Solution
Incorporating a magnetic shield, such as a ferromagnetic material on the accelerating electrode or around the ion gun, to reduce the leakage magnetic field and suppress orbital shifts of the electron beam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a permanent magnet is used in the Penning discharge type ion gun to generate high plasma density, then ionization efficiency is improved, but leakage magnetic field causes electron beam curvature during observation
Solution Approach 1:
A magnetic shield is introduced as an intermediary component between the permanent magnet and the electron beam path. The magnetic shield, made of ferromagnetic material, intercepts and redirects the leakage magnetic field, preventing it from curving the electron beam while allowing the permanent magnet to maintain high plasma density for efficient ionization.
Solution Approach 2:
The harmful leakage magnetic field is extracted and separated from the useful ionization function. By positioning the magnetic shield between the permanent magnet and the observation region, the harmful magnetic field lines are diverted through the shield material, isolating the electron beam from the adverse magnetic influence while preserving the ion gun's ionization performance.
2Quantity of substance
If high plasma density is achieved by increasing magnetic flux density, then ion emission amount increases, but electron beam orbital shift occurs during microscope observation
Solution Approach 1:
The magnetic shield serves as a mediator that allows high plasma density to be maintained in the ion gun while protecting the electron beam path from magnetic field interference. The shield creates a magnetic field boundary that confines the high-density plasma region without allowing the magnetic field to extend into the electron beam observation path, thus maintaining both ion emission quantity and beam position accuracy.
3Device complexity
If a simple and small Penning discharge type ion gun is used, then device complexity is reduced, but leakage magnetic field cannot be controlled
Solution Approach 1:
A magnetic shield is introduced as a mediator component that adds minimal structural complexity to the compact ion gun design. The shield, positioned within or around the ion gun chamber, effectively controls the leakage magnetic field without requiring fundamental redesign of the ion gun structure, thus maintaining simplicity while adding necessary magnetic field control capability.
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 magnetic shield effectively reduces the leakage magnetic field, preventing electron beam curvature and allowing for stable observation and processing, while also enabling control of the axial magnetic field intensity for improved ionization efficiency and milling performance.
Implementation Method 1
a Penning discharge type ion gun having a simple configuration and being small in size. The Penning discharge type ion gun is configured such that electrons emitted from cathodes make a turning motion by a magnetic field from a permanent magnet
Implementation Method 2
the ion milling system includes a magnetic shield that reduces a leakage magnetic field from the permanent magnet
Implementation Method 3
The Penning discharge type ion gun is configured such that electrons emitted from cathodes make a turning motion by a magnetic field from a permanent magnet and strike against gas introduced into the ion gun, thereby causing ionization
Implementation Method 4
Part of cations generated in an ionization chamber are passed through a cathode outlet hole, accelerated by an accelerating electrode, and emitted to outside from an accelerating electrode outlet hole
Implementation Method 5
since an electron emitted from an electron microscope column takes on a property that an orbit thereof is curved even by a very weak magnetic field
Implementation Method 6
An ion milling system is a processing system that causes bombardment of a sample by accelerated ions and that cuts the sample using sputtering that the ions dislodge atoms and molecules
Data Source
AI summary
To provide an ion milling system that can suppress an orbital shift of an observation electron beam emitted from an electron microscope column, the ion milling system includes: a Penning discharge type ion gun 100 that includes a permanent magnet 114 and that generates ions for processing a sample; and a scanning electron microscope for observing the sample, in which a magnetic shield 172 for reducing a leakage magnetic field from the permanent magnet 114 to the electron microscope column is provided.