Capacitive Silicon Microphone

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

    Research output: Contribution to journalArticle in a proceedings journalScientificpeer-review

    2 Citations (Scopus)


    A capacitive silicon microphone has been fabricated. The component consists of two freestanding polysilicon membranes, a low-stress bending membrane and a high-stress backplate, which are separated by an air gap. Sound pressure changes the capacitance between the membranes. A back-chamber is arranged by encapsulation and static pressure changes are prevented with small equalisation holes in the bending membrane. The component is fabricated combining bulk and surface micromachining techniques. Silicon substrates are etched in TMAH and sacrificial oxide between the membranes is etched in PSG-etch followed by freeze drying to prevent sticking. The measured acoustic sensitivity of the microphone with 1 × 1 mm2 membrane was 2mV/Pa (1 kHz frequency) and the resolution 35 dB (A-weighted sound level).

    Original languageEnglish
    Pages (from-to)275-278
    Number of pages4
    JournalPhysica Scripta: Topical Issues
    Publication statusPublished - 1 Dec 1999
    MoE publication typeA4 Article in a conference publication
    Event18th Nordic Semiconductor Meeting, NSM18 - Linköping, Sweden
    Duration: 8 Jun 199810 Jun 1998


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