AVS 49th International Symposium
    Surface Science Thursday Sessions
       Session SS+EL-ThA

Paper SS+EL-ThA9
Probing the Chemistry of Impurities with STM: The Profound Effect of Dissolved Oxygen on Silicon Etching

Thursday, November 7, 2002, 4:40 pm, Room C-112C

Session: Growth & Etching on Semiconductor Surfaces
Presenter: S.P. Garcia, Cornell University
Authors: S.P. Garcia, Cornell University
H. Bao, Cornell University
M.A. Hines, Cornell University
Correspondent: Click to Email
A new technique has been developed to quantify the surface reactivity of impurities, which combines the exquisite defect sensitivity of scanning tunneling microscopy (STM) and the analytical capabilities of atomistic kinetic Monte Carlo (KMC) simulations. This technique exploits kinetic competition between the impurity and a reference etchant to produce impurity-concentration-dependent changes in nanoscale etch morphology. These changes are then quantified using STM measurements and KMC simulations. We used this technique to measure the site-specific reactivity of dissolved O@sub 2@ -- a ubiquitous impurity in aqueous solutions -- with H-terminated Si(111) surfaces. The site-specific reactivity of O@sub 2@(aq) is surprisingly anisotropic. Oxidation of the highly strained dihydride step site is four times faster than oxidation of the relatively unstrained monohydride step site. Both steps are 10@super 4@ times more reactive than terrace sites. FTIR measurements of the Si-H stretch vibration showed that dissolved O@sub 2@ inserts O atoms into surface Si-Si backbonds without removing the H-termination. Dissolved O@sub 2@ does not attack Si-H bonds, since neither Si-H consumption nor silanol production is observed.