Title :
Tungsten contamination in BF2 implants
Author :
Liebert, Reuel B. ; Angel, Gordon C. ; Kase, Masataka
Author_Institution :
Varian Ion Implant Syst., Gloucester, MA, USA
Abstract :
Evidence is presented showing that tungsten contamination can be detected in the range of 10-110 ppm of implanted dose for BF2 + implants. The contamination is absent in As+ implants. Analysis of isotopic ratios of the contaminant atoms, beam energy dependence of the contamination levels, and energy of the contaminant ions (based on SIMS analysis) is used to deduce the origin of the contamination. Direct analysis of W-bearing ions, molecular breakup reactions and charge change are evaluated as potential causes and we conclude that charge and or decomposition change of a molecular species is the only viable candidate as the root cause. Specific molecular decompositions are offered as potential causes. Possible methods of elimination and/or minimization of the contaminant are presented
Keywords :
boron compounds; chemical variables measurement; ion implantation; mass spectroscopic chemical analysis; secondary ion mass spectra; surface contamination; tungsten; BF2+ implants; SIMS analysis; Si:BF2,W; W-bearing ions; beam energy dependence; charge change; contaminant atoms; contaminant ion energy; contamination levels; decomposition change; direct analysis; implanted dose; ion implantation processing; isotopic ratios; molecular breakup reactions; molecular decompositions; molecular species; tungsten contamination; Acceleration; Atomic beams; Contamination; Data mining; Implants; Ion beams; Isotopes; Magnetic separation; Tungsten; Voltage;
Conference_Titel :
Ion Implantation Technology. Proceedings of the 11th International Conference on
Conference_Location :
Austin, TX
Print_ISBN :
0-7803-3289-X
DOI :
10.1109/IIT.1996.586151
