This paper demonstrates that defect control is greatly improved when using the protected environment of a vertical reactor cluster tool comprising a preclean station. The cluster tool investigated combines the established process stability of vertical reactors with new capabilities as native oxide removal, ultraclean wafer transport, and reactors shielded from enviromental contamination. An adequate combination of clean gas usage and leak tightness makes it possible to apply HF vapor etching effectively in order to control the properties of the silicon-silicon oxide interface. For different precleaning conditions, interface and bulk contamination was measured, the sources identified, and the effect of improvements monitored. To this end, several electrical parameters were determined, including the analysis of Qhd and Ehd. Quantitative TXRF and SIMS techniques were used to correlate the results with metallic and organic contamination.

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