A new condenser microphone with a p+ silicon membrane

✍ Scribed by T. Bourouina; S. Spirkovitch; F. Baillieu; C. Vauge

• Publisher: Elsevier Science
• Year: 1992
• Tongue: English
• Weight: 774 KB
• Volume: 31
• Category: Article
• ISSN: 0924-4247
• DOI: 10.1016/0924-4247(92)80095-k

✦ Synopsis

This paper presents the results of investigations which have led to the batch fabrication of a new condenser microphone and the subsequent measurement of its characteristics. With an overall siz of 3 x 4 x 0.8 mm3 including an hybrid JFET, the microphone has an integrated back-chamber and is achieved with a very simple IC-compatible process comprising only five photolithography steps. The diaphragm has a thickness of I pm. It is fabricated with the classical EDP boron etch-stop technique. Frequency responses of the microphone with a bias voltage of 20 V show sensitivities of 3.5 and 0.4 mV/Pa, depending on the fabrication parameters; the corresponding bandwidths are 2.5 and 20 kHz, respectively. Two methods of measurement have been set up in order to determine the built-in tension of heavily boron-doped silicon and have led to the same value of 70 MPa.