Patent ID: 7074634

Claim:
A surface micromachining process for manufacturing Electroacoustic transducers, particularly ultrasonic transducers, said transducers comprising a silicon semiconductor substrate ( 1 ), on an upper surface of which one or more membranes ( 18 ) of resilient materials are supported by a structural layer ( 11 ) of insulating material, rigidly connected to said silicon semiconductor substrate ( 1 ), said resilient material having a Young's modulus not lower than 50 GPa, said membranes ( 18 ) being metallised, said transducers including one or more lower electrodes ( 23 , 25 ), rigidly connected to said silicon semiconductor substrate ( 1 ), the process comprising the following steps: A. providing said silicon semiconductor substrate ( 1 ), B. realising an intermediate product comprising: a sacrificial layer ( 8 , 8 â€²), and a structural layer ( 11 ) of insulating material, rigidly connected to an upper surface of said silicon semiconductor substrate ( 1 ), the surfaces of said sacrificial layer ( 8 , 8 â€²) and of said structural layer ( 11 ) not in contact with said silicon semiconductor substrate ( 1 ) being substantially co-planar, C. depositing a layer ( 15 ) of said resilient material on said sacrificial layer ( 8 , 8 â€²) and on said structural layer ( 11 ), and D. releasing said membranes ( 18 ) of said resilient material by removing said sacrificial layer ( 8 , 8 â€²) from the product obtained according to said step C., said process being characterised in that said structural layer ( 11 ) includes silicon monoxide.