Particle Source Tip Geometry via Field-Induced Chemical Etching
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Solution Overview
Problem
Current particle sources for electronic microscopes and focused ion beam systems face limitations such as larger virtual source diameter, lower resolution, and uneven energy distribution, which restrict their application in micro- and nano-technology, particularly in biological sample detection and micro-manufacture.
Innovation Solution
A particle source is manufactured using field-induced chemical etching (FICE) and field evaporation to form a metal wire tip with a small curvature radius and a larger base, resulting in a high beam current density, small beam opening angle, and reduced energy spread, enabling improved spatial coherence of electron beams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If Schottky field emission electron source is used, then lifetime is improved, but virtual source diameter increases and resolution decreases
Solution Approach 1:
The patent applies field-induced chemical etching (FICE) and field evaporation to precisely control the geometric parameters of the tip, achieving a curvature radius of 1-10 nm. This parameter optimization resolves the contradiction by creating a tip geometry that maintains long lifetime while minimizing virtual source diameter to achieve high resolution
2Quantity of substance
If liquid metal ion source is used, then beam current density is improved, but virtual source diameter increases and energy distribution becomes uneven
Solution Approach 1:
The patent optimizes the tip curvature radius to 1-10 nm through FICE and field evaporation, achieving a balance that maintains high beam current density while reducing virtual source diameter. The precise geometric control ensures uniform energy distribution across the beam
Solution Approach 2:
The patent uses metal wires with specific material properties (tungsten, tantalum, rhenium, molybdenum, hafnium, or niobium) that combine high melting points with suitable etching characteristics, enabling the formation of optimized tip geometries that resolve the contradiction between current density and source diameter
3Manufacturing precision
If gas field ion source is used, then virtual source diameter is reduced and energy distribution is improved, but beam current density decreases
Solution Approach 1:
The patent reduces the tip curvature radius to 1-10 nm through FICE and field evaporation, optimizing the geometry to maximize beam current density while maintaining the small virtual source diameter characteristic of gas field ion sources. This precise parameter control resolves the contradiction between source size and beam intensity
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 method produces a particle source with enhanced beam current density, reduced virtual source diameter, and improved energy distribution, suitable for high-resolution imaging and micro-manufacturing applications.
Implementation Method 1
The head of the metal wire is reduced from lateral sides by field induced chemical etching to form the tip of the particle source
Implementation Method 2
the surface electric field at the top of the metal wire is increased by the FICE to be greater than a field evaporation electric field of material for the metal wire, so that metal atoms at the top of the metal wire are evaporated off
Data Source
Figure 1~2B
Figure 2C~3
Figure 4A~4B
AI summary
The present disclosure provides a particle source comprising a base having a gently-shaped top, and a tip formed as a tiny protrusion on the top of the base.