Single-Atom Tip for Stable Ion Beam Emission
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Solution Overview
Problem
Existing ion and electron sources with multi-atom terminations face issues such as reduced beam current stability, susceptibility to contamination, and increased downtime due to the formation of tungsten oxides or nitrides, and the difficulty in maintaining a single-atom termination structure, leading to unstable image quality and processing in electron microscopes and focused ion beam apparatuses.
Innovation Solution
A tip with a single-atom termination structure is achieved by using a thin line member made of tungsten, niobium, or molybdenum, with a protruding portion of iridium, platinum, or osmium, and a supply portion to maintain the single-atom termination, allowing for continuous and stable ion or electron beam emission through heating and voltage application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a tungsten tip with trimer termination is used in a gas field ion source, then the tip can be manufactured with a simple sharpening process, but the beam current is reduced to 1/3 and image quality is degraded
Solution Approach 1:
The invention changes the termination structure parameter from multi-atom (trimer) to single-atom termination. This is achieved by controlling the crystallographic orientation of the tip apex and using selective etching or deposition processes to isolate a single atom at the termination point, thereby improving beam current precision while maintaining manufacturing feasibility
Solution Approach 2:
The invention employs composite material structures where a tungsten tip (or other base material) is combined with a single atom of different material at the termination point. This composite structure allows the bulk properties of the base material to be maintained while the surface termination is optimized for single-atom emission, resolving the contradiction between manufacturing simplicity and beam precision
2Duration of action of moving object
If a tungsten tip is heated in a vacuum ion chamber, then the tip can be sharpened and maintained, but oxygen or nitrogen adheres to the surface forming oxides or nitrides that cause damage
Solution Approach 1:
The invention applies inert atmosphere techniques by maintaining the tip in a high-vacuum environment during heating and sharpening operations. The vacuum chamber is kept at sufficiently low pressure to prevent oxidation and nitridation of the tip surface, even when heated to high temperatures. This allows prolonged tip operation without degradation from harmful chemical reactions
Solution Approach 2:
The invention performs preliminary surface treatment of the tip by heating and cleaning it in the vacuum chamber before use. This preliminary action removes any adsorbed gases or contaminants from the surface, creating a clean starting state that prevents subsequent oxidation and nitridation during operation, thereby extending tip life
3Reliability
If a single-atom termination structure is maintained on a tip, then beam current stability is improved, but the structure is difficult to maintain and requires complex processing
Solution Approach 1:
The invention enables the tip to self-maintain its single-atom termination structure through controlled heating and field evaporation processes. When the tip is heated in the presence of an electric field, atoms at the apex are selectively removed or rearranged to restore the single-atom termination configuration. This self-service mechanism maintains beam current stability without requiring complex external intervention or manual repositioning
Solution Approach 2:
The invention employs feedback control where the beam current characteristics are monitored and used to adjust heating power or field strength to maintain the single-atom termination. The system detects deviations in beam current that indicate termination structure changes and automatically corrects them through controlled field evaporation or heating, simplifying the maintenance process while ensuring reliability
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 solution enables long-term, high-stability operation of gas field ion sources and electron sources, extending the operating life of focused ion beam apparatuses and electron microscopes, and enabling high-precision processing and imaging with reduced downtime and cost.
Implementation Method 1
a gas field ion source (GFIS) of a focused ion beam (FIB) apparatus
Implementation Method 2
a distal end of the tip be sharpened so as to be formed of about several atoms
Implementation Method 3
subjecting the resultant to electropolishing or heating
Implementation Method 4
the single-atom termination structure can be repeatedly regenerated
Data Source
AI summary
Provided is a tip capable of repeatedly regenerating a single-atom termination structure in which a distal end is formed of only one atom. A tip (1) having a single-atom termination structure includes: a thin line member (2) made of a first metal material; a protruding portion (4) made of a second metal material, which is formed at least in a distal end portion (2a) of the thin line member (2), and has a distal end terminated with only one atom; and a supply portion (5) made of the second metal material to be supplied to the protruding portion (4), which is formed in the vicinity of the distal end portion (2a) of the thin line member (2).