IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Semiconductors Monday Sessions
       Session SC+SS-MoM

Paper SC+SS-MoM6
Fundamental Aspects of Silicon Oxidation: O@sub 2@ and H@sub 2@O Reaction with Si(100) and H-passivated Si Surfaces

Monday, October 29, 2001, 11:20 am, Room 122

Session: Oxidation of Semiconductors
Presenter: Y.J. Chabal, Agere Systems
Authors: Y.J. Chabal, Agere Systems
A. Esteve, LAAS, France
X. Zhang, Rutgers University
E. Garfunkel, Rutgers University
K. Raghavachari, Agere Systems
Correspondent: Click to Email
Examining the initial oxidation steps of both clean and H-passivated silicon surfaces is important to unravel the mechanism for oxygen insertion and oxide formation in realistic environments. We have combined high resolution infrared absorption spectroscopy (IRAS) with quantum chemical (QC) cluster calculations and kinetic Monte Carlo (KMC) simulations to determine the energetics and kinetics of O@sub 2@ and H@sub 2@O thermal oxidation of Si(100) and H-passivated Si(100) and Si(111) surfaces. Specific local structures are determined by comparing experimental IRAS data of both Si-O and Si-H vibrational modes with vibrational frequencies determined from first principles QC calculations of energetically stable model structures. KMC simulations are then used to analyze the cumulative effect of a series of elementary reaction steps on extended growth of an oxide layer. For the clean Si(100)-(2x1) surface, oxygen is readily incorporated into the surface from either O@sub 2@ or H@sub 2@O with a thermodynamic propensity to agglomerate but with different kinetics. KMC simulations show that oxide growth is governed by two fundamental phenomena: (i) charge transfer arising from oxygen insertion into the Si-Si bonds and (ii) hydrogen passivation and/or dangling bond formation at the surface. The charge transfer strongly affects the energetics (thermodynamics) of further oxygen agglomeration (the ability for an oxygen atom to leave an oxygenated dimer unit); the presence/absence of dangling bonds then compounds this effect by further modifying the oxygen migration kinetics. For H-passivated surfaces, both O@sub 2@ and H@sub 2@O are found to incorporate into the Si-SiH backbonds without loss of surface hydrogen. We find an oxygen insertion energy of 1.6 - 1.7 eV, while the oxidation kinetics of different surface structures appear to be dominated by O2 access to Si-Si bonds (locally blocked by unreactive Si-H species).