Fd. Mcdaniel et al., IMPURITY DETERMINATION IN ELECTRONIC MATERIALS BY ACCELERATOR MASS-SPECTROMETRY, Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms, 89(1-4), 1994, pp. 242-249
An Accelerator Mass Spectrometry (AMS) facility has been developed in
the Ion Beam Modification and Analysis Laboratory (IBMAL) at the Unive
rsity of North Texas (UNT) through a collaboration between UNT, Texas
Instruments, Inc., the National Science Foundation, and the Office of
Naval Research. The computer-controlled AMS instrument. which allows a
utomated mass scans of stable isotopes in solid materials, removes mol
ecular interferences which are present in Secondary Ion Mass Spectrome
try (SIMS) allowing higher sensitivities for some elements than SIMS.
A new low sample-contamination, raster-scanning, depth-profiling ion s
ource has been constructed for this AMS facility. This source coupled
to the AMS system should provide sensitivities of ppt (1 part in 10(12
) or 10(10) atoms/cm3) for many elements in the periodic table. The AM
S system design is discussed including ion generation with the new ion
source, ion analysis with the tandem accelerator and spectrometer, an
d ion detection hardware and software. Each of these functions may be
viewed as a sub-assembly with a dedicated IBM computer controlling the
appropriate functions. Results using the AMS facility to characterize
trace element impurities in Si and CdZnTe electronic materials are di
scussed.