Ab. Emerson et al., SURFACE-ANALYSIS, DEPTH PROFILING, AND EVALUATION OF SI CLEANING PROCEDURES BY POSTIONIZATION SPUTTERED NEUTRAL MASS-SPECTROMETRY, Journal of vacuum science & technology. B, Microelectronics and nanometer structures processing, measurement and phenomena, 14(1), 1996, pp. 301-304
The characterization of metallic impurities and dopant profiles near o
r on wafer surfaces is increasingly important as Si device features sh
rink. Conventional methods of surface analysis are ineffective in the
near-surface region. We have used laser postionization sputtered neutr
al mass spectrometry to determine the efficacy of dry cleaning methods
of silicon surfaces and perform shallow doping depth profiling. Unlik
e secondary ion mass spectrometry, postionization is free of matrix ef
fects in the near-surface region (<100 Angstrom), and permits quantita
tive analysis. The ability of this technique to track the cleaning of
contaminated wafers is demonstrated. Hydrocarbon contamination on the
surface limits the determination of Ca. The importance of the ubiquito
us hydrocarbon contamination on wafers is also seen in interpreting ve
ry shallow depth profiles. Preliminary results demonstrate that ultrah
igh intensity (10(14) W/cm(2)) postionization shows promise as a nonse
lective, but effective means for surface analysis and shallow depth pr
ofiling. (C) 1996 American Vacuum Society.