AVS 50th International Symposium
    High-k Gate Dielectrics and Devices Topical Conference Tuesday Sessions
       Session DI-TuA

Paper DI-TuA7
Chemically Abrupt Interfaces between Lanthanum Aluminate and Silicon for Alternative Gate Dielectric Applications

Tuesday, November 4, 2003, 4:00 pm, Room 317

Session: High-k Dielectric Characterization
Presenter: L.F. Edge, Pennsylvania State University
Authors: L.F. Edge, Pennsylvania State University
D.G. Schlom, Pennsylvania State University
S.A. Chambers, Pacific Northwest National Laboratory
C.L. Hinkle, North Carolina State University
G. Lucovsky, North Carolina State University
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LaAlO@sub 3@ is one of the most promising alternative gate dielectrics for the replacement of SiO@sub 2@ in silicon MOSFETs. Single crystalline LaAlO@sub 3@ is known to have a dielectric constant of 24 and an optical bandgap of 5.6 eV. The band offsets between LaAlO@sub 3@ and Si have been predicted to be in the range 2.1 to 3.5 eV for electrons and 1.0 to 1.9 eV for holes. It will be shown that LaAlO@sub 3@ is stable in contact with silicon under standard MOSFET processing conditions. Epitaxial Si has been grown by MBE on single crystals of LaAlO@sub 3@ and annealed at 1026C, which is a standard implant activation anneal for MOSFETs, and the interface remained stable and free of SiO@sub 2@. A major challenge in the growth of alternative gate dielectrics on Si is the formation of unwanted SiO@sub 2@ at the interface. One technique to prevent the formation of SiO@sub 2@ is to grow in a low temperature and excess oxidant regime. We have investigated the oxidation kinetics of Al and La, both individually and together (codeposition), to determine the minimum oxygen partial pressure required to achieve fully oxidized LaAlO@sub 3@. Using these optimized conditions, amorphous LaAlO@sub3@ films as thin as 1.0 nm have been grown on silicon by MBE. AES and XPS analyses indicate that the films are fully oxidized and show no SiO@sub 2@ at the interface, even after prolonged exposure of the films to air.