Abstract
The atomic layer control of SiO2 growth can be accomplished using binary reaction sequence chemistry. To achieve this atomic layer growth, the binary reaction SiCl4 + 2H2O → SiO2 + 4 HCl can be divided into separate half-reactions: (A) SiOH*+SiCl4→SiOSiCl*3+HCl, SiCl*+H2O→SiOH*+HCl,. where the asterisks designate the surface species. Under the appropriate conditions, each half-reaction is complete and self-limiting and repetitive ABAB... cycles should produce layer-by-layer-controlled SiO2 deposition. The atomic layer growth of SiO2 thin films on Si(100) was achieved at temperatures from 600-680 K with reactant pressures from 1-50 Torr. These experiments were performed in a small high pressure chamber situated in an ultrahigh vacuum (UHV) apparatus. This design couples high pressure conditions for film growth with an UHV environment for surface analysis using laser-induced thermal desorption (LITD), temperature-programmed desorption (TPD) and Auger electron spectroscopy (AES). The controlled growth of a stoichiometric and chlorine-free SiO2 film on Si(100) was demonstrated using these techniques. SiO2 growth rates of approximately 0.73 ML of oxygen (1.1 Å of SiO2) per AB cycle were obtained at 600-680 K. Additional vibrational spectroscopic studies performed in a second vacuum chamber utilized transmission Fourier transform infrared (FTIR) experiments on high surface area, oxidized porous silicon to monitor the surface species during the binary reaction sequence chemistry. These FTIR measurements observed the SiCl stretching vibration at 625 cm-1 and the SioH vibration at 3740 cm-1 and confirmed that each half-reaction was complete and self-limiting. These studies illustrate the feasibility of atomic-layer-controlled SiO2 growth and have determined the reactant pressures and substrate temperatures required for the SiO2 binary reaction sequence chemistry.
Original language | English (US) |
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Pages (from-to) | 135-152 |
Number of pages | 18 |
Journal | Surface Science |
Volume | 334 |
Issue number | 1-3 |
DOIs | |
State | Published - Jul 10 1995 |
Funding
This research was supported by the Office of Naval Research under Contract No. N00014-92-J-1353. O.S. is grateful to the Israeli Academy of Sciences for a Wolfson postdoctoral fellowship. M.L.W. acknowledges AT&T Bell Labs for a graduate fellowship. S.M.G. acknowledges the National Science Foundation for a Presidential Young Investigator Award (1988-1994).
ASJC Scopus subject areas
- Condensed Matter Physics
- Surfaces and Interfaces
- Surfaces, Coatings and Films
- Materials Chemistry