Gas Field Ionization Ion Source Dual-Mode Emission Control
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Solution Overview
Problem
Conventional gas field ionization ion sources struggle to achieve high ion beam currents necessary for high SNR analysis and high-speed processing without damaging the emitter electrode, as increasing gas pressure leads to rapid degradation of the apex structure.
Innovation Solution
The ion source operates in two states: a first state with a lower extraction voltage and gas pressure for small region emission, and a second state with a higher extraction voltage and gas pressure for larger region emission, allowing for increased ion beam current while minimizing electrode damage by controlling the gas pressure and extraction voltage to prevent excessive ionization and adsorption of impurities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the gas pressure is increased to increase ion beam current, then the ion beam current increases, but the emitter electrode is damaged more rapidly due to impurity gas adsorption and electric field evaporation
Solution Approach 1:
The ion source switches between two operational modes (small region emission and large region emission) depending on the required ion beam current. The system dynamically adjusts the extraction voltage and gas pressure settings to match the operational requirements, allowing high current operation when needed while preserving the electrode during low current operations
Solution Approach 2:
The invention changes the operational parameters (extraction voltage and gas pressure) to switch between two distinct emission regions. By adjusting these parameters, the system can operate at high ion beam currents using the large region emission mode without continuously degrading the apex structure, as the emission occurs from a broader area rather than concentrating stress on the micro-protrusion
2Productivity
If the extraction voltage is increased to increase ion beam current, then the ion beam current increases, but the apex structure of the emitter electrode is damaged due to excessive electric field evaporation
Solution Approach 1:
The system dynamically selects between two operational modes based on the required ion beam current. When high current is needed, the large region emission mode is activated with appropriate voltage and pressure settings that distribute the electric field stress across a larger area, preventing concentrated damage to the apex micro-protrusion
Solution Approach 2:
The emission region is segmented into two distinct modes: small region emission from the apex micro-protrusion for low current applications, and large region emission for high current applications. This segmentation allows the system to use the appropriate emission region based on requirements, preserving the delicate apex structure when high currents are not needed
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 approach enables stable high ion beam currents for micro-region observation and high SNR analysis without frequent regeneration of the emitter electrode, maintaining the integrity of the nano-pyramid structure and reducing the probability of electrode damage.
Implementation Method 1
a first extraction voltage is applied, with the pressure of an ionization gas being set to a first gas pressure, ions are emitted from a first ion emission region on an apex of an emitter electrode
Implementation Method 2
Gas field ionization ion source
Data Source
AI summary
In the case of a conventional gas field ionization ion source, it was not possible to carry out an analysis with a high S/N ratio and a high-speed machining process because the current amount of an ion beam is small. In view of these problems, the present invention has been devised, and its object is to obtain a large ion beam current, while suppressing a probability of damaging an emitter electrode. The present invention is characterized by a process in which an ion beam is emitted at least in two operation states including a first operation state in which, when a first extraction voltage is applied, with the gas pressure being set to a first gas pressure, ions are emitted from a first ion emission region at the apex of the emitter electrode, and a second operation state in which, when a second extraction voltage that is higher than the first extraction voltage is applied, with the gas pressure being set to a second gas pressure that is higher than the first gas pressure, ions are emitted from a second ion emission region that is larger than the first ion emission region.