Focused Ion Beam Field Source Using Ionic Liquid Emitter

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Solution Overview

Problem

Existing ion sources face challenges in generating stable, high-brightness negative ion beams with minimal chromatic and spherical aberrations, particularly for applications involving dielectric or electrically floating substrates, where charge build-up and surface damage are concerns, and require complex setups or limited operational temperatures.

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 aberrations, focused and directed using an electrostatic lens and deflector, allowing operation at various polarities and temperatures, and capable of producing negative ions for biological, dielectric, or conductive substrates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional ion sources are used to generate positive ion beams, then ion beam generation is achieved, but charge build-up occurs on dielectric or electrically floating substrates causing surface damage and limiting focusing capabilities

Engineering Contradiction:

Improvecharge build-up preventionVSAvoidsurface damage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent inverts the conventional approach by using negative ion beams instead of positive ion beams. Negative ions neutralize positive charge accumulation on dielectric substrates, preventing surface damage and maintaining focusing capabilities throughout the beam application process.

Inventive Principle:

Principle #13The other way round (Inversion)

2Adaptability or versatility

If ionic liquids are used in open architectures, then vacuum compatibility is achieved, but ion beam stability and brightness are compromised

Engineering Contradiction:

Improvevacuum system compatibilityVSAvoidion beam stability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent introduces a capillary structure as an intermediary between the ionic liquid reservoir and the beam extraction region. The capillary confines the ionic liquid, provides a controlled emission aperture, and maintains stability while allowing the system to operate in vacuum environments through the low vapor pressure of the ionic liquid.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If high current density is used to improve beam brightness, then beam quality improves, but chromatic and spherical aberrations increase

Engineering Contradiction:

Improvebeam brightnessVSAvoidbeam focus precision

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent optimizes multiple parameters simultaneously: capillary diameter (1-100 micrometers), ionic liquid viscosity, applied voltage, and temperature control. These parameter changes enable high current density extraction while minimizing aberrations through controlled emission conditions and optimized field geometry.

Inventive Principle:

Principle #35Parameter changes

4Reliability

If complex ion source setups are used to achieve stable negative ion beams, then beam stability improves, but device complexity increases

Engineering Contradiction:

Improvenegative ion beam stabilityVSAvoidsource structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines multiple functions into the capillary structure: it serves as the ionic liquid reservoir, the emission aperture, the field emission cathode support, and the vacuum seal. This merging eliminates the need for separate components, reducing overall device complexity while maintaining stable negative ion beam generation.

Inventive Principle:

Principle #5Merging (Combining)

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, reducing charge build-up and surface damage, enabling precise focused ion beam applications with improved resolution and efficiency, and operates effectively across a range of substrates and temperatures.

Implementation Method 1

A power supply applies a voltage to the emitter with respect to an electrode, sufficient to generate a stable high brightness beam of negative ions

Methodology Applied

Scientific EffectField emission: Electron Beam

Implementation Method 2

An electrostatic lens and a deflector focuses and directs the beam to a target

Methodology Applied

Scientific EffectElectrostatic lens: Electrostatic Lens

Implementation Method 3

An electrostatic lens and a deflector focuses and directs the beam to a target

Methodology Applied

Scientific EffectElectrostatic deflection: Electrostatics

Data Source

PatentUS8030621B2Focused ion beam field source

Publication Date: 2011.10.04 MASSACHUSETTS INST OF TECH

AI summary

An apparatus for producing ions can include an emitter having a first end and a second end. The emitter can be coated with an ionic liquid room-temperature molten salt. The apparatus can also include a power supply and a first electrode disposed downstream relative to the first end of the emitter and electrically connected to a first lead of the power supply. The apparatus can also include a second electrode disposed downstream relative to the second end of the emitter and electrically connected to a second lead of the power supply.