Capacitive microphone with low-stress polysilicon membrane and high-stress polysilicon backplate

Altti Torkkeli, Outi Rusanen, Jaakko Saarilahti, Heikki Seppä, Hannu Sipola, Jarmo Hietanen

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    75 Citations (Scopus)

    Abstract

    A capacitive single-chip silicon microphone with very low-stress polysilicon membrane was fabricated. A mechanism for stress-releasing due to the high stress of the perforated membrane was introduced. With the achieved stress level of 2 MPa, a microphone with the membrane area of 1 mm2 can be optimally designed, although the measured components did not show the optimal resolution due to excessive acoustic resistance. With a membrane area of 1 mm2, the acoustical sensitivity was 4 mV/Pa (at 1 kHz) and the noise equivalent sound level was 33.5 dB (A), which are adequate values for many applications. The packaged components were tested with a thermal cycle between -40 °C and +60 °C, and due to low packaging-related stresses, no buckling of the membranes was observed.

    Original languageEnglish
    Pages (from-to)116-123
    JournalSensors and Actuators A: Physical
    Volume85
    Issue number1
    DOIs
    Publication statusPublished - 25 Aug 2000
    MoE publication typeA1 Journal article-refereed

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    Keywords

    • capacitive
    • microphone
    • polysilicon
    • stress

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