AVS 47th International Symposium
    Dielectrics Thursday Sessions
       Session DI+EL+MS-ThM

Paper DI+EL+MS-ThM4
Core-level Photoemission of Interface States on SiO@sub 2@/Si: Substrate Orientation Effects

Thursday, October 5, 2000, 9:20 am, Room 312

Session: Ultrathin Dielectrics and Interfaces
Presenter: J.E. Rowe, Army Research Office
Authors: J.E. Rowe, Army Research Office
J.W. Keister, North Carolina State University
J.F.T. Wang, North Carolina State University
G.J. Jackson, Rutgers University
T.E. Madey, Rutgers University
D.E. Aspnes, North Carolina State University
Correspondent: Click to Email
High resolution soft X-ray photoelectron spectroscopy (SXPS) with synchrotron radiation is used to study the interface of mis-cut SiO@sub 2@/Si(100) [i.e. stepped interface] of device quality ultrathin gate oxides. Our studies were performed on thin oxides grown by thermal oxidation in pure O@sub 2@ at a temperature of 600@degree@C and pressure of ~760 Torr. Our data can be well described by five different Si species due to Si in different oxidation states which are usually labeled Si@super 0@, Si@super +1@, Si@super +2@, Si@super +3@, and Si@super +4@. We have studied a number of samples prepared as described above and find that the energies relative to the Si0 peak are 0.95 eV, 1.80 eV, 2.50 eV, and 4.00 eV for the Si@super +1@, Si@super +2@, Si@super +3@, and Si@super +4@ peaks respectively. For this study, we define the transition region as the region containing Si in intermediate oxidation states (Si@super +1@, Si@super +2@, Si@super +3@). We find a transition-region Si suboxide concentration of 1.3 x 10@super 15@ cm@super -2@ assuming an escape depth of ~7 @Ao@ at a photon energy of 200 eV for samples annealed after growth at temperatures of ~900 @degree@C . This transition region is that in excess of the density ~1 monolayer of Si@super +1@ expected for the most abrupt SiO@sub 2@/Si(111) interface in terms of the Si(111) layer density of 7.8 x 10@super 14@ cm@super -2@. The I@sub 1@ interface peak is largest for (111) and decreases substantially for (113), (110), and for stepped (100) substrates. The total interface density appears to be lowest for Si(100) with a modest step density introduced by a 2@degree@ mis-cut. The step-dependent behavior is consistent with that reported using second harmonic generation. The total concentration of suboxide derived from SXPS data is dependent on the uniformity of SiO@sub 2@ films as well as data modeling, i.e., fitting of the data; both will be discussed.