Stress-profile characterization and test-structure analysis of single and double ion-implanted LPCVD polycrystalline silicon

M. A. Benítez, L. Fonseca, J. Esteve, M. S. Benrakkad, J. R. Morante, J. Samitier, J. A. Schweitz

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    14 Citations (Scopus)

    Abstract

    A very low stress gradient across the polysilicon layers is required for the fabrication of large micromechanical structures based on surface-micromachining technologies. In this work the residual stress and the stress gradient of 2 μm thick LPCVD polysilicon layers are presented as a function of deposition, doping and annealing conditions. Low stress gradients are obtained by optimizing the doping profile using a two-step deposition and implantation process. The results obtained by mechanical test structures are corroborated by micro Raman measurements. The effects of the polysilicon stress gradient on surface-micromachined accelerometers are analysed. Polysilicon layers with low tensile stress and a stress gradient lower than 5 MPa μm-1 are required for the fabrication of surface-micromachined z-accelerometers.
    Original languageEnglish
    Pages (from-to)718-723
    JournalSensors and Actuators, A: Physical
    Volume54
    Issue number1-3
    DOIs
    Publication statusPublished - 1 Jan 1996

    Keywords

    • Polysilicon
    • Stress gradients
    • Surface micromachining

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