Papers by Author: Mehran Mehregany

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Authors: Chien-Hung Wu, Juyong Chung, Moon Hi Hong, Christian A. Zorman, P. Pirouz, Mehran Mehregany
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Authors: Christian A. Zorman, Mehran Mehregany
1451
Authors: A.J. Fleischman, S. Roy, Christian A. Zorman, Mehran Mehregany
889
Authors: J. Dunning, Xiao An Fu, Mehran Mehregany, Christian A. Zorman
Abstract: This paper details the characterization of polycrystalline SiC (poly-SiC) thin films deposited by low pressure chemical vapor deposition. Films were deposited on both Si and SiO2- coated Si substrates using dichlorosilane (SiH2Cl2) and acetylene (C2H2) as precursor gases. Low residual tensile stress films were deposited at 900°C at a pressure of 2 Torr using SiH2Cl2 and C2H2 (5% in H2) flow rates of 35 sccm and 180 sccm, respectively. XRD analysis of these films indicated a (111) 3C-SiC orientation regardless of substrate material. Both resistivity (1.3 -cm) and residual stress gradient (17 MPa/μm) were found to be relatively low and decreased as the film thickness increased. Unintentional nitrogen doping is responsible for the low resistivity measurements and its concentration in the films was about 1.86 x 1016 cm-3. Poly-SiC films exhibiting near-zero residual tensile stress, low stress gradient and relatively low resistivity have favorable properties for design and fabrication of MEMS devices.
1103
Authors: Chien-Hung Wu, Christian A. Zorman, Mehran Mehregany
541
Authors: J. Dunning, Xiao An Fu, Srihari Rajgopal, Mehran Mehregany, Christian A. Zorman
1523
Authors: Sheng Jin, Srihari Rajgopal, Mehran Mehregany
Abstract: We report two improvements of our all-silicon carbide (SiC) micromachined capacitive diaphragm-based pressure sensors: Ti/TaSi2/Pt contact metallization to enhance temperature cycling durability and a 0.5 μm-thin sensing gap to further improve sensor sensitivity. Three sensors with 0.5 μm and 1.5 μm sensing gaps were packaged individually in high temperature ceramic packages and characterized to designed (static) pressures of 2.1 MPa (300 psi), 3.4 MPa (500psi) and 6.9 MPa (1000 psi) up to 550°C. For the 3.4 MPa range sensor (0.5 μm gap, 70 μm diaphragm radius), a sensitivity of 0.06 fF/Pa and a nonlinearity of 2.0% was obtained at 550°C in contact mode operation. In comparison, the 2.1 MPa range sensor (1.5 μm gap, 95 μm diaphragm radius) demonstrated a sensitivity of 0.07 fF/Pa and a nonlinearity of 4.6% at 550°C in contact mode operation. The 6.9 MPa range sensor (1.5 μm gap, 70 μm diaphragm radius) demonstrated a sensitivity of 0.03 fF/Pa and a nonlinearity of 4.0% at 500°C, also in contact mode.
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Authors: Xiao An Fu, J. Dunning, Christian A. Zorman, Mehran Mehregany
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