Gas Field Ion Source with Magnetic Stabilization
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Solution Overview
Problem
Conventional gas field ion sources face challenges in achieving high-resolution sample observation due to vibration of the emitter tip, instability of the ion beam current, and brightness unevenness in observation images, primarily caused by impurity gases and inadequate heat management.
Innovation Solution
The ion beam device incorporates a gas field ion source with a superconducting emitter base mount, a non-contact magnetic interaction mechanism, and a cooling system using a Gifford-McMahon type refrigerator to maintain extremely low temperatures, along with a beam limiting aperture tilted to prevent impurity gas adhesion and a high-vacuum environment to stabilize the ion beam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the pressure of the ion material gas is increased to increase ion radiation angle current density, then the ion current increases, but the ion beam collides with neutral gas and the ion current decreases
Solution Approach 1:
The patent divides the vacuum chamber into two separate chambers: a first chamber containing the ion source where ion material gas is supplied at higher pressure, and a second chamber where the ion beam is extracted at lower pressure. This segmentation allows the ion source to operate at optimal gas pressure for high ion current density while preventing excessive collisions that would reduce ion beam quality.
2Quantity of substance
If the emitter tip temperature is decreased to increase gas molecular density, then the ion radiation angle current density increases, but the ion beam device complexity increases
Solution Approach 1:
The patent uses a gas supply mechanism that introduces ion material gas (such as helium or hydrogen) into the first chamber to increase the gas molecular density around the emitter tip. This pneumatic approach allows cooling of the emitter tip without requiring complex cryogenic infrastructure, as the gas pressure enhancement compensates for the temperature reduction to maintain high ion current density.
3Power
If a focused ion beam is used to process the sample, then the sputtering action is enhanced, but the resolution of sample observation is reduced
Solution Approach 1:
The patent employs dynamic control of the ion beam parameters, allowing the system to switch between different operational modes. The ion beam can be focused for sputtering processing when needed, and defocused or adjusted for high-resolution observation. This dynamic adjustment enables the system to optimize between sputtering power and observation resolution based on the specific experimental requirements.
4Quantity of substance
If the ion beam is focused to increase current density, then the ion radiation angle current density increases, but the vibration of the emitter tip increases
Solution Approach 1:
The patent introduces a magnetic field as an intermediary to control and stabilize the ion beam. The magnetic field focuses and guides the ion beam without requiring mechanical adjustment of the emitter tip, thereby maintaining high ion current density while minimizing emitter tip vibration. The magnetic field acts as a non-contact mediator that achieves beam control without mechanical disturbance.
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 enables high-resolution sample observation with a stable ion beam, reducing vibration and brightness unevenness, and enhancing the ion beam current, thereby improving the overall performance of the ion microscope.
Implementation Method 1
applies a high voltage of a few kV or higher to the emitter tip to ionize gas molecules, and extracts the resultant as an ion beam
Implementation Method 2
cool the emitter tip to extremely low temperature and decrease the temperature of gas around the emitter tip to low temperature
Implementation Method 3
a mechanism which produces a noncontact magnetic interaction between the emitter base mount and the vacuum vessel is provided
Implementation Method 4
a mechanism which produces a noncontact magnetic interaction between the emitter base mount and the vacuum vessel is provided
Data Source
AI summary
Provided is an ion beam device provided with a gas electric field ionization ion source which can prevent an emitter tip from vibrating in a non-contact manner. The gas electric field ionization ion source is comprised of an emitter tip (21) for generating ions; an emitter base mount (64) for supporting the emitter tip; an ionizing chamber which has an extraction electrode (24) opposed to the emitter tip and which is configured so as to surround the emitter tip (21); and a gas supply tube (25) for supplying gas to the vicinity of the emitter tip. The emitter base mount and a vacuum container magnetically interact with each other.