An Ion Gun typically is an instrument that generates a beam of heavy ions with a well defined energy distribution. The

ion beam An ion beam is a beam of ions, a type of charged particle beam. Ion beams have many uses in electronics manufacturing (principally ion implantation) and other industries. There are many ion beam sources, some derived from the mercury vapor ...

is produced from a plasma that has been confined within a volume. Ions of a particular energy are extracted, accelerated, collimated and/or focused. The ion gun is composed of an

ion source An ion source is a device that creates atomic and molecular ions. Ion sources are used to form ions for mass spectrometers, optical emission spectrometers, particle accelerators, ion implanters and ion engines. Electron ionization Elect ...

, extraction grid structure and a collimation/lensing structure. The plasma can be made up of an inert or reactive gas (e.g. N⁺ and O⁺) or an easily condensable substance (e.g. C⁺ and B⁺). The plasma can be formed from molecules that contain the substance which will form the beam, in which case, these molecules must be fragmented then ionized (e.g. H and CH₄ can together be fragmented and ionized to create a beam for depositing diamond-like carbon films). The ion

current density In electromagnetism, current density is the amount of charge per unit time that flows through a unit area of a chosen cross section. The current density vector is defined as a vector whose magnitude is the electric current per cross-sectional ...

(or similarly the ion flux), the ion energy spread, and the resolution of the ion beam are key factors in ion gun design. The ion current density is controlled by the

, the energy spread is determined primarily by the extraction grid, and the resolution is determined primarily by the optical column. The ion gun is an important component in

surface science Surface science is the study of physical and chemical phenomena that occur at the interface of two phases, including solid–liquid interfaces, solid– gas interfaces, solid– vacuum interfaces, and liquid– gas interfaces. It includes the ...

in that it provides the scientist with a means to sputter etch a surface and generate an elemental or chemical depth profile.Giannuzzi, L.A., Stevie, F.A., "Introduction to focused ion beams: instrumentation, theory, techniques, and practice", Springer (2005), p.315 Modern ion guns can produce beam energies from 10eV to more than 10keV.

Measurement and Detection

A Nanocoulombmeter in combination with a

Faraday cup A Faraday cup is a metal (conductive) cup designed to catch charged particles. The resulting current can be measured and used to determine the number of ions or electrons hitting the cup. The Faraday cup was named after Michael Faraday who first ...

can be used to detect and measure the beams emitted from ion guns.

References

{{Reflist * Mattox, D.M., "Handbook of Physical Vapor Deposition (PVD) Processing", 2nd ed., Elsevier Inc., Oxford (2010), p. 185 * Riviére, J.C., "Handbook of surface and interface analysis: methods for problem-solving", 2nd ed., CRC Press, Boca Raton (2009), p. 73-5 * Cherepin, T.V., "Secondary ion mass spectroscopy of solid surfaces", English ed., VNU Science Press, The Netherlands (1987), p. 38-9 * Briggs, D., "Surface analysis of polymers by XPS and static SIMS", Cambridge University Press (1998), p. 89 Ions

Measurement and Detection

See also

References