MEMS PRODUCTS

microfab has gained distinctive expertise in surface micromachining technology dedicated to the design and serial fabrication of acoustic MEMS devices, such as silicon microphones and ultrasound transducers (c-MUTs).

The elementary building blocks of all capacitive acoustic transducers are membranes, either actuated by electrostatic forces or by sound waves, which have to be well controlled in terms of mechanical stress and layer thickness. microfab uses dedicated LPCVD (low-pressure chemical vapor deposition) processes, such as silicon-rich nitrides or in-situ doped polysilicon in combination with sacrificial layer technologies to build such functional layers. All technologies are proven to be capable for serial production in high-volumes and are routinely applied for customized components running at microfab.

microfab´s capacitive micromachined ultrasonic transducer (c-MUT) is a relatively new concept in the field of ultrasonic transducers. Most of the commercial ultrasonic transducers today are based on piezoelectric materials. c-MUTs are constructed on silicon using micromachining techniques. A cavity is formed in a silicon substrate, and a thin layer suspended on the top of the cavity serves as a membrane on which a conductive layer acts as top electrode, together with the silicon substrate which serves as a bottom electrode.

As c-MUTs are micromachined devices, it is easier to construct 2D arrays of transducers using this technology. This means large numbers of c-MUTs could be included in a transducer array.

To achieve a high frequency operation using c-MUTs is easier due to its smaller dimensions. The frequency of operation depends on the cell size (cavity of membrane), and on the stiffness of the material used as a membrane.