Characterisation of the beam plasma in high current, low energy ion beams for implanters

J. Fiala, D. G. Armour, J. A. Van Den Berg, A. J.T. Holmes, R. D. Goldberg, E. H.J. Collart

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review


The effective transport of high current, positive ion beams at low energies in ion implanters requires the a high level of space charge compensation. The self-induced or forced introduction of electrons is known to result in the creation of a so-called beam plasma through which the beam propagates. Despite the ability of beams at energies above about 3-5 keV to create their own neutralising plasmas and the development of highly effective, plasma based neutralising systems for low energy beams, very little is known about the nature of beam plasmas and how their characteristics and capabilities depend on beam current, beam energy and beamline pressure. These issues have been addressed in a detailed scanning Langmuir probe study of the plasmas created in beams passing through the post-analysis section of a commercial, high current ion implanter. Combined with Faraday cup measurements of the rate of loss of beam current in the same region due to charge exchange and scattering collisions, the probe data have provided a valuable insight into the nature of the slow ion and electron production and loss processes. Two distinct electron energy distribution functions are observed with electron temperatures ≥ 25 V and around 1 eV. The fast electrons observed must be produced in their energetic state. By studying the properties of the beam plasma as a function of the beam and beamline parameters, information on the ways in which the plasma and the beam interact to reduce beam blow-up and retain a stable plasma has been obtained.

Original languageEnglish
Title of host publicationIon Impantation Technology
Subtitle of host publication16th International Conference on Ion Implantation Technology, IIT 2006
EditorsKaren Kirkby, Russell Gwilliam, Andy Smith, David Chivers
PublisherAmerican Institute of Physics Publising LLC
Number of pages5
ISBN (Print)9780735403659
Publication statusPublished - 28 Dec 2006
Externally publishedYes
Event16th International Conference on Ion Implantation Technology - Marseille, France
Duration: 11 Jun 200616 Nov 2006
Conference number: 16


Conference16th International Conference on Ion Implantation Technology
Abbreviated titleIIT 2006
Internet address


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