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Title: Development of ion sources and a quantitative ion implantation technique for secondary ion mass spectrometry

Thesis/Dissertation ·
OSTI ID:5600118

The design and construction of an alkali ion source is discussed. An extraction lens system is used to extract an increased fluence of emitted ions. Limitations on the maximum current obtained exist and are discussed as an explanation to the lower currents observed. Focused alkali ion beams of approx.3 ..mu..m are recorded, however, beam current densities are less than hoped. The maximum ion current measured for cesium ions (filtered through a primary mass filter) reached approx.2.5 ..mu..A with an acceptable beam stability of less than a few percent over a half hour period. The primary ion column of a secondary ion mass spectrometer (Cameca IMS 3f) has been used as an ion implanter to prepare calibrated standards, in situ, for quantitative SIMS analysis, with an accuracy better than 10%. C, O, N, F, Cs, and Rb were implanted with this technique, and with the appropriate ion source most elements in the periodic tables may be used. The technique has been used to determine oxygen concentrations in contaminated TiSi/sub 2/ films by implanting a reference level of /sup 18/O into a portion of the film. The use of Cs primary ion bombardment to enhance negative secondary ion yields has been routine in SIMS for almost ten years. In that time, formal studies have been performed to determine whether Cs is indeed the alkali metal of choice for optimized negative ion yields. A survey of ion source performance for Cs and other alkali metals is reported. The conventional W frit surface ionization source works remarkably well for Rb/sup +/, K/sup +/, and Na/sup +/ generation. Negative secondary ion sensitivities, sputtering yields, and useful yields are compared for a variety of typical materials - Si, GaAs, and Pt/sub 2/Si.

Research Organization:
Arizona State Univ., Tempe (USA)
OSTI ID:
5600118
Resource Relation:
Other Information: Thesis (Ph. D.)
Country of Publication:
United States
Language:
English