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Title: Selective ion source

A ion source is described wherein selected ions maybe extracted to the exclusion of unwanted ion species of higher ionization potential. Also described is a method of producing selected ions from a compound, such as P{sup +} from PH{sub 3}. The invention comprises a plasma chamber, an electron source, a means for introducing a gas to be ionized by electrons from the electron source, means for limiting electron energy from the electron source to a value between the ionization energy of the selected ion species and the greater ionization energy of an unwanted ion specie, and means for extracting the target ion specie from the plasma chamber. In one embodiment, the electrons are generated in a plasma cathode chamber immediately adjacent to the plasma chamber. A small extractor draws the electrons from the plasma cathode chamber into the relatively positive plasma chamber. The energy of the electrons extracted in this manner is easily controlled. The invention is particularly useful for doping silicon with P{sup +}, As{sup +}, and B{sup +} without the problematic presence of hydrogen, helium, water, or carbon oxide ions. Doped silicon is important for manufacture of semiconductors and semiconductor devices. 6 figs.
Inventors:
Issue Date:
OSTI Identifier:
228056
Assignee:
Univ. of California, Oakland, CA (United States) PTO; SCA: 360601; 426000; PA: EDB-96:080160; SN: 96001584031
Patent Number(s):
US 5,517,084/A/
Application Number:
PAN: 8-280,273
Contract Number:
AC03-76SF00098
Resource Relation:
Other Information: PBD: 14 May 1996
Research Org:
University of California
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 42 ENGINEERING NOT INCLUDED IN OTHER CATEGORIES; ION SOURCES; DESIGN; SILICON; CRYSTAL DOPING; BEAM EXTRACTION; PHOSPHORUS IONS; PHOSPHORUS HYDRIDES; ARSENIC IONS; BORON IONS; SEMICONDUCTOR MATERIALS; SEMICONDUCTOR DEVICES

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