A theoretical and experimental study of liquid-metal ion sources and their application to focused ion-beam technology
A key parameter of liquid metal ion source (LMIS) operation is the current-voltage (I(V)) relationship. Some issues surrounding this relationship, which is complicated by severe space-charge near the emitter, are examined for a LMIS. A simple technique is introduced which relies on the principle of momentum conservation within a simple diode structure and enables the solution of space charge problems without resorting to the Poisson equation. As an illustration of this approach, the result of Stern-Gossling-Fowler is easily derived. This method is then applied to the problem of modeling the I(V) characteristic of a LMIS. A simple and physically intuitive criterion is derived which demonstrates that the ratio of the viscous drag force on the emitter to the force of the ion beam impinging on the collector determine whether the ion current is dominated by the flow of liquid metal or by the space charge in the beam. This explains, for the first time, how these two factors are related. Another result is that, contrary to currently accepted thinking, it is not the flow impedance per se which influences the ion current but the product of the film thickness and the flow impedance. Since the advent of LMIS, the understanding of their fundamental properties and their application to focused ion beam (FIB) technology have followed parallel developments. One of the goals of the research presented in this dissertation has been to expand the applications of the liquid metal ion source. The major difficulties encountered during their fabrication, testing and operation are due primarily to contamination by oxygen, carbon bearing gases and backsputtering of material to the source, particularly from the extraction electrode.
- Research Organization:
- Oregon Graduate Center, Beaverton, OR (USA)
- OSTI ID:
- 6047656
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
Molecular & Chemical Physics-- Beams & their Reactions
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BEAMS
CONSERVATION LAWS
DIFFERENTIAL EQUATIONS
DIMENSIONS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELEMENTS
EQUATIONS
FLUIDS
IMPEDANCE
ION BEAMS
ION SOURCES
LASERS
LIQUID METALS
LIQUIDS
MACHINING
MATHEMATICAL MODELS
METALS
PARTIAL DIFFERENTIAL EQUATIONS
PHYSICAL PROPERTIES
POISSON EQUATION
SEMICONDUCTOR DEVICES
SEMICONDUCTOR LASERS
SOLID STATE LASERS
SPACE CHARGE
THICKNESS
USES