Low pH Chemical Etch Route for Smooth H-Terminated Si(100) and Study of Subsequent Chemical Stability


To form atomically flat H-passivated Si(100) surfaces, wet chemical etching of sacrificial SiO2 layer has been examined. Roughness and chemical overlayer thickness, as monitored by ellipsometry shows a minima at an optimal solution of 1:0.5:30 HF(49wt%):H2SO4 (98wt%):H2O. A mechanistic study offers no evidence for a chemical smoothing from preferential non-Si(100) facet etching. Silicon planarization can be induced by rapid thermal annealing RTA of chemical oxides. The H-terminated Si(100) surfaces are found to be moderately reactive to ambient conditions as monitored by in-situ ellipsometry and Auger analysis. Atomic force microscopy (AFM) measurements show Si(100) surfaces to have a rms ~1.0Å and Rmax values of 1.6–0.9Å. With measured roughness incorporate into ellipsometric model, a 5Å native oxide overlayer is rapidly incorporated into the Si(100) surface.

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The authors thank the Office of Naval Research, Semiconductor Research Corporation and National Science Foundation for financial support.

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Correspondence to B. J. Hinds.

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Hinds, B.J., Aspnes, D.E. & Lucovsky, G. Low pH Chemical Etch Route for Smooth H-Terminated Si(100) and Study of Subsequent Chemical Stability. MRS Online Proceedings Library 477, 191–196 (1997). https://doi.org/10.1557/PROC-477-191

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