Resonance ionization of sputtered atoms: Quantitative analysis in the near-surface region of silicon wafers

Journal Article · Sat Feb 01 04:00:00 EST 1997 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.52609· OSTI ID:579999

Calaway, W F ^[1]; Spiegel, D R; Marshall, A H ^[2]; Downey, S W ^[3]; Pellin, M J ^[1]

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1. Material Science, Chemical Technology, and Chemistry Divisions, Argonne National Laboratory, Argonne, Illinois 60439 (United States)
2. Department of Physics, Trinity University, San Antonio, Texas 78212 (United States)
3. Lucent Technologies, Orlando, Florida 32819 (United States)

The unambiguous identification and quantification of low levels of metallic impurities on Si wafers are difficult problems due to the rapidly changing chemical activity near the surface. Air-exposed Si surfaces typically possess a native oxide layer several atoms thick plus a top monolayer of various silicon-containing molecules. Resonance ionization spectroscopy (RIS) used for postionization in secondary neutral mass spectrometry (SNMS) is uniquely suited to this task. The high sensitivity of this technique allows detection of metals at parts per billion levels with monolayer sensitivity. The high selectivity of RIS allows unambiguous identification of elements, while the reduced matrix effects of SNMS allow quantification of the photoionized element. Characterization of Si surfaces using RIS/SNMS has been explored by measuring the concentration profiles of Ca in the near-surface region of Si wafers of varying degrees of cleanliness. Calcium detection can be problematic due to the isobaric interference with SiC, particularly in the near-surface region during fabrication of devices due to the use of organic photoresist. Three different resonance ionization schemes for Ca have been examined and compared for effectiveness by calculating detection limits for Ca in Si in the chemically active near-surface region. {copyright} {ital 1997 American Institute of Physics.}

• Research Organization: Argonne National Laboratory (ANL), Argonne, IL
• Sponsoring Organization: USDOE
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 579999
• Report Number(s): CONF-961110--
• Journal Information: AIP Conference Proceedings, Journal Name: AIP Conference Proceedings Journal Issue: 1 Vol. 392; ISSN APCPCS; ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
40 CHEMISTRY
66 PHYSICS
ARGON 40 BEAMS
CALCIUM ADDITIONS
CONCENTRATION RATIO
IMPURITIES
ION SCATTERING ANALYSIS
KEV RANGE 01-10
RESONANCE IONIZATION MASS SPECTROSCOPY
SILICON