SURFACE-ANALYSIS, DEPTH PROFILING, AND EVALUATION OF SI CLEANING PROCEDURES BY POSTIONIZATION SPUTTERED NEUTRAL MASS-SPECTROMETRY

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.