Preparation and Application of a Piezoelectric Film for an Ultrasound Transducer

A micromachined ultrasound transducer, comprising:

• a substrate;
• an opening formed in the substrate, the opening being filled with a backing material;
• a first metal layer disposed over the backing material;
• an adhesion-promoting layer disposed over the first metal layer;
• a piezoelectric layer disposed over the adhesion-promoting layer, the piezoelectric layer being substantially thicker than the adhesion-promoting layer;
• and
• a second metal layer disposed over the piezoelectric layer;
• wherein the first metal layer, the adhesion-promoting layer, the piezoelectric layer, and the second metal layer are each a part of a transducer membrane of the micromachined ultrasonic transducer.

An ultrasound system, comprising:

• an imaging component that includes a flexible elongate member and a piezoelectric micromachined ultrasound transducer (PMUT) coupled to a distal end of the elongate member, wherein the PMUT includes:
• a substrate having a front surface and a back surface opposite the first surface;
• a well located in the substrate, the well extending from the back surface of the substrate to, but not beyond, the front surface of the substrate, wherein the well is filled by a backing material configured to absorb energy transmitted by the piezoelectric film;
• a first metal layer disposed over the well, wherein a segment of the first metal layer disposed over the well has an arcuate shape;
• an adhesion-promoting film disposed over the first metal layer;
• a piezoelectric film disposed over the adhesion-promoting film, the piezoelectric film being substantially thicker than the adhesion-promoting film, wherein the piezoelectric film has a β phase crystallinity greater than 60%, and wherein the piezoelectric film contains polyvinylidene fluoride (PVDF), polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE), or polyvinylidene fluoride-tetrafluoroethylene (PVDF-TFE);
• and
• a second metal layer disposed over the piezoelectric film;
• an interface module configured to engage with a proximal end of the elongate member;
• and
• an ultrasound processing component in communication with the interface module.