Emitter Tip Milling via Ion Current Feedback and Gas-Voltage Switching
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Solution Overview
Problem
Existing ion beam devices face challenges in maintaining atomic sharpness of emitter tips with high reproducibility, leading to device downtime due to the need for precise adjustments and the use of expensive, short-lived position-sensitive detectors, and temperature fluctuations, which affect the stability and resolution of the ion beam.
Innovation Solution
An ion beam device that measures the current of a helium ion beam to adjust the flow rate of nitrogen or oxygen gases and extraction voltage, allowing for emitter tip sharpening without a position-sensitive detector, using hydrogen ions for both sharpening and monitoring, and optimizing gas pressure to reduce downtime and improve reproducibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a position-sensitive detector is used to monitor emitter tip sharpness, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces the mechanical position-sensitive detector system with an electrical measurement system. Instead of using a detector to physically monitor ion beam position, the invention measures electrical parameters (ion beam current, extraction voltage, gas flow rate) to indirectly determine emitter tip sharpness. This substitution eliminates complex detector hardware while maintaining measurement capability through electrical signal analysis.
Solution Approach 2:
The patent introduces electrical parameters as intermediary variables to connect emitter tip sharpness with measurable quantities. By measuring ion beam current, extraction voltage, and gas flow rate, the system uses these electrical intermediaries to infer tip sharpness without direct physical detection. This intermediary approach simplifies the measurement system while preserving precision.
2Manufacturing precision
If emitter tip is continuously sharpened to maintain atomic sharpness, then manufacturing precision is improved, but device downtime increases
Solution Approach 1:
The patent implements a feedback control system that continuously monitors electrical parameters (ion beam current, extraction voltage, gas flow rate) and uses this information to determine when emitter tip sharpening is needed. The feedback mechanism allows the system to maintain atomic sharpness by performing sharpening only when necessary, rather than continuous or frequent sharpening, thereby reducing device downtime while preserving manufacturing precision.
Solution Approach 2:
The patent performs emitter tip sharpening as a preliminary action based on predicted needs rather than waiting for performance degradation. By monitoring electrical parameters that indicate approaching sharpness limits, the system can schedule sharpening operations optimally, preventing both excessive downtime and precision loss.
3Productivity
If gas flow rate is increased to sharpen emitter tip faster, then productivity is improved, but temperature stability deteriorates
Solution Approach 1:
The patent employs dynamic control of gas flow rate during the emitter tip sharpening process. Instead of maintaining a constant high flow rate, the system adjusts the gas flow dynamically based on real-time feedback from electrical parameter measurements. This dynamic adjustment allows the system to achieve fast sharpening when needed while maintaining temperature stability during critical phases, resolving the contradiction between productivity and temperature control.
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 solution enables high-reproducibility atomic sharpness of emitter tips, reduces device downtime, and maintains high resolution and sensitivity of the ion beam, eliminating the need for expensive detectors and minimizing temperature adjustments.
Implementation Method 1
a high voltage is applied to an emitter tip made of a metal and having a radius of curvature of about 100 nm or less at a tip end, an electric field is concentrated at the tip end, a gas (an ionized gas) is introduced into the vicinity of the tip end, and gas molecules are field ionized and extracted as an ion beam
Implementation Method 2
a first ion beam is irradiated onto a sample to form a cross-sectional surface of the sample
Implementation Method 3
an extraction voltage is applied between an emitter and an extraction electrode, gas at a tip end of the emitter is ionized into gas ions by the applied voltage, and the gas ions are extracted toward the extraction electrode
Data Source
AI summary
An object of the invention is to provide an ion beam device capable of sharpening an emitter tip end to an atomic level with high reproducibility while reducing a device downtime. The ion beam device according to the invention measures a current of a helium ion beam, and switches, according to a measurement result, between a first operation of adjusting a flow rate of a nitrogen gas or an oxygen gas and a second operation of adjusting an extraction voltage.