Ionic Liquid Negative Ion Source for Aberration Control
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Solution Overview
Problem
Existing ion sources face challenges in generating stable, high-brightness negative ion beams with minimal aberrations, particularly for applications requiring precision and chemical reactivity, such as focused ion beam systems and microelectronics, due to limitations in thermal stability, compatibility, and polarity constraints of liquid metal and capillary-based electrospray technologies.
Innovation Solution
An apparatus and method utilizing an emitter coated with room-temperature ionic liquid molten salts, where a voltage is applied to generate a stable high-brightness beam of negative ions with minimal chromatic and spherical aberrations, using an electrostatic lens and deflector to focus and direct the beam to a target, allowing for operation at negative polarity and improved chemical reactivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If liquid metal ion sources are used to generate ion beams, then high brightness emission can be achieved, but thermal stability and compatibility issues arise due to high operating temperatures
Solution Approach 1:
The patent changes the fundamental parameter of the ion source material from liquid metal to ionic liquid, enabling operation at room temperature while maintaining high brightness emission. This parameter change resolves the contradiction by eliminating the need for high temperature operation that caused thermal stability and compatibility issues in liquid metal sources.
Solution Approach 2:
The patent uses ionic liquids, which are composite materials consisting of organic and inorganic cations and anions, to create an ion source that combines the high brightness emission capability of liquid metals with the thermal stability of room-temperature liquids. This composite approach allows operation without high temperature while maintaining emission performance.
2Adaptability or versatility
If capillary-based electrospray technology is used, then ion beam generation is possible, but polarity constraints and compatibility limitations reduce versatility
Solution Approach 1:
The patent applies ionic liquids to enable the ion source to operate in both positive and negative polarity modes, making the system universal and adaptable to different application requirements. This multi-functionality resolves the polarity constraints of capillary-based electrospray technology while maintaining beam stability through the unique properties of ionic liquids.
3Duration of action of moving object
If traditional ion sources operate at high temperatures, then ion emission can be sustained, but thermal decomposition and material compatibility become problematic
Solution Approach 1:
The patent changes the operating temperature parameter from high temperature to room temperature by using ionic liquids, which remain in liquid phase at moderate temperatures. This parameter change sustains ion emission continuity while eliminating thermal decomposition and material compatibility problems that occur with traditional high-temperature ion sources.
Solution Approach 2:
The patent uses ionic liquids that can be easily replenished on the emitter surface, creating a effectively inexhaustible supply of ion-emitting material at room temperature. This approach replaces the need for high-temperature sustained operation with a room-temperature process using readily available ionic liquid coatings.
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 achieves stable, high-brightness negative ion beams with minimal aberrations, enabling enhanced precision and chemical reactivity suitable for focused ion beam applications, including microscopy, lithography, and microelectronics, while avoiding thermal and compatibility issues of traditional sources.
Implementation Method 1
A power supply applies a voltage to the emitter with respect to the electrode, sufficient to generate a stable high brightness beam of negative ions
Implementation Method 2
An electrostatic lens and a deflector focuses and directs the beam to a target
Implementation Method 3
An electrostatic lens and a deflector focuses and directs the beam to a target
Implementation Method 4
These ions are large enough to produce a poorly coordinated mixture that remains in the liquid phase at moderate temperatures. Some of them display super-cooling tendencies in which they remain as liquids well below their nominal freezing points. Just as their inorganic cousins (i.e., simple salts such as NaCl, KBr, etc.) at their melting points (typically >850° C.), they exhibit appreciable electrical conductivity at room temperature, making them suitable for electrostatic deformation and subsequent Taylor cone formation.
Data Source
AI summary
An apparatus for producing negative ions including an emitter coated with an ionic liquid room-temperature molten salt, an electrode positioned downstream relative to the emitter, a power supply that applies a voltage to the emitter with respect to the electrode. The power supply is sufficient to generate a stable high brightness beam of negative ions having minimal chromatic and spherical aberrations in the beam. An electrostatic lens and deflector is used to focus and direct the beam to a target.