AVS 46th International Symposium
    Surface Science Division Tuesday Sessions
       Session SS2+EM-TuA

Paper SS2+EM-TuA3
Micrometer-scale "Grooves" and Step Bunching during Extended Oxidation-induced Etching of Si(001) Surfaces

Tuesday, October 26, 1999, 2:40 pm, Room 6C

Session: Semiconductor Surface Chemistry
Presenter: J.F. Nielsen, The Ohio State University
Authors: J.F. Nielsen, The Ohio State University
M.S. Pettersen, Otterbein College
J.P. Pelz, The Ohio State University
Correspondent: Click to Email
We have used in-situ STM and ex-situ AFM to observe large-scale step rearrangement on Si(001) surfaces that were heated by DC current at ~1000@super o@C for 3-43 hrs in ~10@super -5@ Torr of oxygen. Depending on sample miscut and current direction, these conditions produced either (1) no significant step rearrangement, (2) large scale (5-10µm) step-bunched regions (with separation increasing roughly as t@super 1/2@), or (3) large "grooves", consisting of a highly-ordered sinusoidal step array with in-phase alignment. The grooved and step-bunched phases can coexist on the same wafer, forming neighboring semi-coherent patches extending over hundreds of microns. The interface between the two phases is remarkably sharp. The step-bunching was also observed on surfaces heated in vacuum (no oxygen), and may be similar to electromigration-related behavior reported by Doi et al.@footnote 1@ Regular arrays of "crossing steps" are also seen on the step bunched regions. It is not yet clear whether oxygen is required for the formation of the grooves. The grooves appear to be qualitatively different from the "wavy" steps reported by Tromp and Reuter@footnote 2@ in that they extend coherently over large areas and are not confined to sample regions of extremely low-miscut. We are currently mapping out the precise conditions necessary to produce each surface phase, and are using the wide terraces resulting from step-bunching in on-going studies of spontaneous step creation on ultra-flat Si(001) surfaces. @FootnoteText@ @footnote 1@ T. Doi, M. Ichikawa, and S. Hosoki, Phys. Rev. B. 55, 1864 (1997) @footnote 2@ R. M. Tromp and M. C. Reuter, Phys. Rev. Lett. 68, 820 (1992).