Berlin 2005 – wissenschaftliches Programm

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O: Oberflächenphysik

O 36: Postersitzung (Elektronische Struktur, Grenzfl
äche fest-flüssig, Halbleiteroberfl
ächen und -grenzfl
ächen, Nanostrukturen, Oberfl
ächenreaktionen, Teilchen und Cluster, Struktur und Dynamik reiner Oberfl
ächen)

O 36.32: Poster

Montag, 7. März 2005, 15:00–18:00, Poster TU F

Ultra-trace analysis and speciation of low Z contaminants on silicon wafer surfaces by TXRF-NEXAFS employing monochromatized undulator radiation — •B. Beckhoff, R. Fliegauf, M. Kolbe, M. Müller, J. Weser, and G. Ulm — Physikalisch-Technische Bundesanstalt, Abbestr. 2 - 12, 10587 Berlin, Germany

The Physikalisch-Technische Bundesanstalt (PTB) develops total-reflection x-ray fluorescence (TXRF) analysis in the soft x-ray range, providing a means for the quantitation of low Z contaminants on silicon wafer surfaces at its monochromator beamline for undulator radiation at BESSY II. The absolute lower levels of detection of TXRF analysis for low Z elements such as C, N, Na, Mg and Al range between 100 fg and 1 pg. A dedicated instrumentation fully utilizes these excitation conditions: 300 mm Si wafers, as well as 200 mm wafers, are transported directly from their shipping cassettes via a prealigner into a high vacuum load-lock by an adapted commercial equipment front end module. A vacuum robot located inside the load-lock takes the wafer and places it inside the UHV irradiation chamber on an electrostatic chuck mounted on an 8-axis manipulator. Furthermore, the investigation of near-edge X-ray absorption fine structures (NEXAFS) in conjunction with TXRF is able to contribute to the speciation of minute amounts of low Z and organic compounds. Here, fluorescence count-rates normalized to the incident radiant power were recorded at the K-edges of C, N and O. The PTB instrumentation offers off-line reference measurements to assess surface cleaning procedures and multi-elemental nano-layered systems deposited on wafers.