Silicon Cleaning with Hydrogen Peroxide Solutions: A High Energy Electron Diffraction and Auger Electron Spectroscopy Study

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Abstract
HEED and Auger electron spectroscopy have been used to evaluate silicon cleaning by sequential immersions in basic and acidic peroxide solutions. It was determined that an oxide film 13–15Aå thick was left after the cleaning. This film contained boron at a surface concentration estimated at 1013–1014 B/cm2. The carbide contamination that results upon heating to 800°C in ultra‐high vacuum was dramatically reduced when compared to wafers cleaned with other techniques. Wafers cleaned with the same process except for a final HF etch had no detectable boron in the surface oxide, formed relatively large amounts of surface silicon carbide at 800°C, and suffered extensive surface roughening with 1100°C heating in vacuum. The protective mechanism of the peroxide cleaning is thought to be due to formation of a thin nearly carbon free oxide layer that volatilizes when the wafers are heated in ultrahigh vacuum. It is recommended that experiments requiring a solvent type cleaning and the heating of Si in ultrahigh vacuum should use this cleaning method.