Thermally Driven In-Situ Removal of Native Oxide Using Anhydrous Hydrogen Fluoride

Abstract

In-situ native-oxide removal is critical for epitaxial single-crystal silicon deposition, for polysilicon emitters and contacts and for ultrathin gate dielectric films in integrated circuit (IC) fabrication. We have developed an in-situ, thermally-driven, anhydrous hydrogen fluoride (AHF)-based native-oxide removal technique in which the wafer is treated by AHF at low temperatures (300–400°C) and a short (10 sec) 950°C ‘spike’ in AHF-H2 immediately prior to Si deposition. This process removes native oxides formed by standard wet cleans such as HCl:H2O2 and NH4OH:H2O2, as well as native oxides formed by the clean-room ambient. Further, the technique is an effective pre-clean for both polysilicon and epitaxial silicon deposition. This flexibility, combined with other salient features such as simplicity and a low thermal budget, make the process eminently suited for IC fabrication.

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Acknowledgments

This work was supported by SRC, Air Force and DARPA. Support from Dr. Mehrdad Moslehi and Texas Instruments is gratefully acknowledged.

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Correspondence to Pushkar P. Apte.

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Apte, P.P., Park, H., Saraswat, K.C. et al. Thermally Driven In-Situ Removal of Native Oxide Using Anhydrous Hydrogen Fluoride. MRS Online Proceedings Library 318, 281–286 (1993). https://doi.org/10.1557/PROC-318-281

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