Ion Source Device With Ion Carpet For High Brightness
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Solution Overview
Problem
Existing electron impact ion sources have limited high-brightness ion beam capabilities and lack versatility in ion species selection, which restricts their application in Focused Ion Beam technologies like FIB machining, imaging, and SIMS analysis.
Innovation Solution
The design incorporates an ionization chamber with a co-planar and concentric electrode ion carpet within the ion source, allowing for high-energy electron beam interaction at elevated pressures, increasing ionization efficiency and enabling the extraction of high-brightness ion beams from various gas species, with RF and DC potential control to manage ion trajectories.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional electron impact ion sources are used, then device complexity is reduced, but ion beam brightness is insufficient
Solution Approach 1:
The ion source is segmented into distinct functional zones: an electron beam generation region with cathode and anode, an ionization chamber where gas is introduced, and an extraction region with electrodes. This segmentation allows each zone to be optimized independently for its specific function while maintaining overall system manageability
Solution Approach 2:
A magnetic field is introduced as an intermediary element to confine and guide the electron beam through the ionization chamber. The magnetic field acts as a mediator that enhances electron-gas interaction efficiency without requiring direct mechanical contact or complex electrode arrangements, thereby achieving high brightness with moderate complexity
2Productivity
If ionization chamber operates at elevated pressure, then ionization efficiency increases, but electron beam scattering increases
Solution Approach 1:
The electron beam energy is dynamically adjusted according to the gas pressure in the ionization chamber. At elevated pressures, the electron beam energy is optimized to maintain sufficient penetration depth and directionality while ensuring adequate ionization efficiency. This dynamic adjustment allows the system to operate effectively across different pressure conditions
Solution Approach 2:
The system changes multiple parameters simultaneously: electron beam energy, gas pressure, and magnetic field strength. By coordinating these parameter changes, the patent achieves high ionization efficiency at elevated pressures while minimizing electron beam scattering through optimized energy selection and magnetic confinement
3Productivity
If high ion beam current is extracted, then productivity increases, but brightness is reduced
Solution Approach 1:
The extraction electrodes are designed with locally optimized properties: the first extraction electrode has a specific geometry and potential configuration that enhances ion collection efficiency, while the second extraction electrode is positioned and configured to maintain beam collimation. This local optimization allows high current extraction without compromising brightness
Solution Approach 2:
The patent transitions from conventional planar electrode extraction to a three-dimensional electrode configuration with specific spatial relationships. The electrodes are positioned at optimized distances and angles relative to the ionization chamber, creating a three-dimensional electric field distribution that simultaneously enables high current extraction and maintains beam brightness through improved ion optical properties
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 configuration enhances ion beam current and brightness, achieving reduced brightness levels of 100 to 500 A m−2 sr−1 V−1, surpassing conventional electron impact sources by a factor of 100 to 500, while maintaining a compact device footprint.
Implementation Method 1
an ionization chamber (120) having an inlet (124) for a gas and an inlet (126) for the electron beam, wherein the ionization chamber (120) comprises an ion beam outlet (128)
Implementation Method 2
surrounded by an ion carpet comprising co-planar and substantially concentric electrodes for funneling ions formed by interaction of the electron beam with the gas towards the ion beam outlet (128) to form an ion beam, and an electronic circuit (134) configured for applying an electric potential to the electrodes
Data Source
AI summary
The invention provides an electron-impact ion source device having high brightness as compared to known Nier-type ion sources, while providing similar advantages in terms of flexibility of the generated ion species, for example. The ionization chamber of the device operates at high pressures and provides for a large number of interactions between the electron beam and the gas molecules.