AVS 53rd International Symposium
    Surface Science Tuesday Sessions
       Session SS-TuP

Paper SS-TuP15
Etching of Si(100)-(2x1) with Cl under Super-Saturated Conditions: A Novel Reaction Pathway

Tuesday, November 14, 2006, 6:00 pm, Room 3rd Floor Lobby

Session: Surface Science Poster Session
Presenter: A. Agrawal, University of Illinois at Urbana-Champaign
Authors: A. Agrawal, University of Illinois at Urbana-Champaign
R.E. Butera, University of Illinois at Urbana-Champaign
J.H. Weaver, University of Illinois at Urbana-Champaign
Correspondent: Click to Email
We investigated the consequences of Cl uptake beyond "saturation" on Si(100)-(2x1), and we discovered a new etching pathway. Si(100)-(2x1) surfaces that were saturated with Cl and had one adatom per dangling bond were exposed to a constant flux of Cl@sub 2@ in the temperature range of 750-850 K. They were then imaged at room temperature with atomic resolution scanning tunneling microscopy. We found that additional Cl can be accommodated via insertion in the Si-Si dimer bond or backbond to produce a super-saturated surface. This allowed the surface to evolve along a novel and previously unobserved etching pathway. Isolated dangling bonds created on the surface by phonon-assisted electron-stimulated desorption (PAESD) of Cl act as mediators for the insertion process. An abstraction reaction to re-saturate the dangling bond with Cl dissociates the incoming Cl@sub 2@ to produce atomic Cl on the surface, which then inserts. SiCl@sub 2@ desorption from the super-saturated surface leads to etching that produces pits elongated along the dimer row direction. The rate limiting step in the etching process is the Cl insertion via the PAESD controlled dangling bond creation. The energetics of the etching process and the sequence of events leading to it will be presented.