An integrated circuit die (1) is disclosed that comprises a substrate (30) defining a plurality of circuit elements； a sensor region (10) on the substrate, the sensor region comprising a layer stack defining a plurality of CMUT (capacitive micromachined ultrasound transducer) cells (11)； and an interposer region (60) on the substrate adjacent to the sensor region. The interposer region comprises a further layer stack including conductive connections to the circuit elements and the CMUT cells, the conductive connections connected to a plurality of conductive contact regions on an upper surface of the interposer region, the conductive contact regions including external contacts (61) for contacting the integrated circuit die to a connection cable (410) and mounting pads (65) for mounting a passive component (320) on the upper surface. A probe including such an integrated circuit die an ultrasound system including such a probe are also disclosed.
