Analytical Sciences

Quantitative Analysis of Trace Bulk Oxygen in Silicon Wafers Using an Inert Gas Fusion Method

Hiroshi UCHIHARA,*  Masahiko IKEDA,* and Taketoshi NAKAHARA**

*HORIBA Application Center, 2 Miyanohigashi, Kisshoin, Minami-ku, Kyoto 601-8510, Japan
**Department of Applied Chemistry, Graduate School of Engineering, Osaka Prefecture University, 1-1, Gakuen-cho, Sakai, Osaka 599-8531, Japan

This paper describes a method for removing oxide film from the surface of silicon wafers using an inert gas fusion impulse furnace and precise determination of bulk oxygen within the wafer. A silicon wafer was cut to about 0.35 g (6 x 13 x 2 mm) and dropped into a graphite crucible. The sample was then heated for 40 s at 1300°C. The wafer's oxide film was reduced by carbon and removed as carbon monoxide. The treated silicon sample was taken out of the graphite crucible and maintained again with the holder of the oxygen analyzer. The graphite crucible was then heated to 2100°C. The treated silicon sample was dropped into the heated graphite crucible and the trace bulk oxygen in the wafer was measured using the inert gas fusion infrared absorption method. The relative standard deviations of the oxygen in silicon wafer samples with the removed surface oxide film were determined to be 0.8% for 9.8 x 10¹⁷ atoms/cm³, and 2.7% for 13.0 x 10¹⁷ atoms/cm³.

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