AVS 49th International Symposium
    Microelectromechanical Systems (MEMS) Thursday Sessions
       Session MM+TF-ThM

Paper MM+TF-ThM10
Growth and Characterization of Doped 3C-SiC Films for Micro- and Nanoelectromechanical Systems

Thursday, November 7, 2002, 11:20 am, Room C-210

Session: Development and Characterization of MEMS Materials
Presenter: C.A. Zorman, Case Western Reserve University
Authors: A.J. Fleischman, Case Western Reserve University
C.A. Zorman, Case Western Reserve University
M. Mehregany, Case Western Reserve University
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An outstanding combination of mechanical, electrical, and chemical properties coupled with recent advances in micromachining make SiC a leading material for microelectromechanical systems requiring performance characteristics that cannot be achieved using Si. For these applications, 3C-SiC is particularly attractive since it is the only SiC polytype that can be grown as single and polycrystalline thin films on Si substrates, giving it a versatility unmatched by the other leading polytypes, specifically 4H- and 6H-SiC. Recently, 3C-SiC has found favor as a material for nanoelectromechanical systems (NEMS), due to the fact that it has a higher acoustic velocity than Si. For nanomechanical resonators, 3C-SiC is currently used solely for its mechanical and chemical properties, while electrically active components are constructed of other materials. Advanced 3C-SiC NEMS will likely capitalize on the electrical properties of 3C-SiC, requiring the use of doped material grown in a well-characterized and highly controllable fashion at the submicron level. In this study, 0.5 micron thick, doped 3C-SiC films were epitaxially grown on (100) Si wafers by APCVD, using silane and propane as precursor gases, hydrogen as a carrier gas, and phosphine and diborane as doping gases. To investigate the effects of dopant incorporation on microstructure, the films were grown as thin multilayers, with a doped layer sandwiched between two undoped layers. SIMS and XRD were used to characterize the multilayer samples. In general, phosphorus doping had no adverse affect on the microstructure of the single crystal films. In contrast, boron doping did influence the microstructure, with high diborane concentrations resulting in the formation of polycrystalline SiC layers. Details concerning the experimental procedure, the effects of outgassing reactor components on the composition of the films, and the implications for submicron 3C-SiC devices will be covered in this presentation.