AVS 53rd International Symposium
    Surface Science Monday Sessions
       Session SS2-MoA

Paper SS2-MoA5
Passivation of Germanium and Silicon Surfaces with Oxide, Hydrogen, Chlorine, and Methyl

Monday, November 13, 2006, 3:20 pm, Room 2004

Session: Functionalization of Semiconductor Surfaces
Presenter: S. Rivillon Amy, Rutgers University
Authors: S. Rivillon Amy, Rutgers University
Y.J. Chabal, Rutgers University
F. Amy, Princeton University
A. Kahn, Princeton University
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Chemical passivation of semiconductor surfaces represents an important part of front end processing for CMOS and other microelectronics applications. The industry has been based primarily on silicon (Si) technology due to the remarkable properties of its oxide, but there is a need to explore higher mobility substrates such as germanium (Ge). Although Si and Ge are both group IV semiconductors, it is well-known that their chemical properties differ dramatically. In particular, Ge has a variety of rather unstable oxides and cannot be chemically passivated as easily as Si. The focus of this talk is on comparing the passivation of germanium surfaces with oxide, hydrogen, chlorine, and methanol to that of the corresponding species on silicon, which have been well characterized. The main characterization techniques to monitor the chemical state of the surface are infrared absorption spectroscopy (IRAS) and X-rays photoelectron spectroscopy (XPS). Besides the formation of much more complex and less stable oxides on Ge, we confirm that H-termination of Ge in HF solutions is much more delicate and invariably leads to atomically rough surfaces with predominance of dihydrides on Ge(100) and trihydrides on Ge(111). To compensate for variation in "native" oxide thickness, a procedure involving H@sub2@O rinsing, oxidation by H@sub2@O@sub2@ immersion and dilute (10 vol%) HF (or HCl) etching has been developed, which reliably leads to H- (or Cl-) termination. XPS data confirm the presence of chlorine (Ge-Cl and Ge-Cl@sub2@) on Ge(100) surface. The stability of both H- and Cl-terminated surfaces is similar: poor in air but stable in clean N@sub2@ environment. The results of methanol adsorption on Ge and Si surfaces illustrate the propensity for Ge to bind with C, which constitutes a clear drawback for microelectronics applications.