Focused Ion Beam Electrode Segmentation for Aberration Control
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Solution Overview
Problem
Existing focused ion beam apparatuses face issues with beam diameter aberration and stability due to ion beam interaction with condenser lens electrodes, leading to reduced performance and shortened ion source stability time.
Innovation Solution
The apparatus incorporates a configuration with a first and second extraction electrode and a control electrode, where the potential of the first and second extraction electrodes is the same, and a control device adjusts the voltage to ensure all ions pass through the condenser lens without contacting the electrodes, reducing aberration and preventing sputtering and secondary electron generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the distance between the extraction electrode and the lens electrode of the condenser lens is reduced to 6 mm or less, then a smaller beam diameter can be realized by reducing aberration, but the ion source stability time is shortened due to increased sputtering material accumulation on the emitter
Solution Approach 1:
The extraction electrode is divided into multiple electrodes (first extraction electrode, second extraction electrode, control electrode) that can be independently controlled. This segmentation allows precise control of the electric field distribution to focus ions through the condenser lens hole while preventing ion beam interaction with the lens electrode, thus resolving the contradiction between achieving small beam diameter and maintaining ion source stability.
2Manufacturing precision
If the distance between the extraction electrode and the lens electrode is reduced, then aberration of the condenser lens is reduced, but secondary electrons and sputter particles are generated from the lens electrode by ion beam irradiation, causing operation instability
Solution Approach 1:
The harmful interaction between the ion beam and the lens electrode is eliminated by extracting the ion beam through a hole in the lens electrode using precisely controlled electric fields from the segmented extraction electrodes. This takes out the problematic irradiation effect while maintaining the beneficial short distance configuration for reduced aberration.
3Reliability
If the lens electrode is irradiated with the ion beam having small energy, then the sputtering yield is reduced and the number of sputter particles is reduced, but the strong lens action cannot be achieved and control of beam trajectory is limited
Solution Approach 1:
The electric field parameters (voltages) of the segmented extraction electrodes are precisely adjusted to create optimal field distribution. This allows the ion beam to be focused through the condenser lens hole with appropriate energy and angle, achieving both strong lens action for good trajectory control and reduced sputtering yield by preventing direct irradiation of the lens electrode.
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 achieves a smaller beam diameter with improved stability and extended ion source operation time by preventing ion beam interaction with the condenser lens electrodes, enhancing the overall performance of the focused ion beam apparatus.
Implementation Method 1
Ions are emitted by a strong electric field generated in the tip end portion of the emitter and an extraction electrode where a voltage is applied
Implementation Method 2
A predetermined energy is applied to the emitted ions by a condenser lens configured with a lens electrode and a ground electrode, and the ions are formed in a beam shape
Implementation Method 3
a surface thereof is always wet with the liquid metal by appropriately energizing a member (filament, or the like) holding the emitter using heating power
Implementation Method 4
The liquid metal is supplied from a liquid metal supplying source to the tip end portion of the emitter, and a surface thereof is always wet with the liquid metal
Data Source
AI summary
A focused ion beam apparatus includes an ion source that emits an ion beam, an extraction electrode that extracts ions from a tip end of an emitter of the ion source, and a first lens electrode that configures a condenser lens by a potential difference with the extraction electrode, the condenser lens focusing the ions extracted by the extraction electrode, in which a strong lens action is generated between the extraction electrode and the first lens electrode so as to focus all ions extracted from the ion source to pass through a hole of the condenser lens including the first lens electrode.