With the aim of developing an air-coupled 2-D array, several typologies were designed, made and characterized. It was shown that all of them work as was expected with a good bandwidth in air but there were some negative effects on their behaviour. The polysilicon layers are heavily doped and in principle they do not need a metallization layer. Nevertheless studying the obtained results it was shown that when a metal electrode is deposited over the polysilicon membrane, the performance of the transducer is improved. Moreover, the acoustic pressure leaving from the etch holes and other acoustical ports added in several designs have a negative effect in the emitted pressure. In this work, square shaped polysilicon membranes with a gold electrode have been simulated and made to reduce these detected negative effects. Two different array apertures, a 1-D array and a sparse 2-D array, have been designed to study their efficiency.

Manufacturing capacitive micromachined ultrasonic transducers (cMUTs) is possible using several low cost standard processes. The multi-user MEMS process (MUMPS) offers this possibility. However, it has some limitations: diaphragms and air gaps of approximately 2 μm thick limit the performance of the resulting device.

Ponencia presentada en el XIX Congreso Internacional de Acústica (ICA2007), Madrid, 2-7 Sep 2007.-- PACS: 43.38.Hz.

Funding from DPI2004-06756-C03-01 and 03 – CICYT projects is acknowledged.

Peer reviewed