Monolithic integration of pmut on cmos

A monolithic integrated device, comprising:

• a single substrate including:
• a substrate layer being a base of the device;
• an inter-layer dielectric disposed on top of the substrate layer and below a passivation layer;
• and
• an electronic circuitry formed within the inter-layer dielectric and supported by the substrate layer, the electronic circuitry comprises a plurality of spaced apart metal layers;
• and
• at least one micromachined ultrasonic transducer, each comprising:
• a bottom electrode disposed on top of the passivation layer;
• a piezoelectric disposed on top of the bottom electrode;
• a top electrode disposed on top of the piezoelectric;
• and
• an elastic layer positioned on top of the top electrode;
• wherein the monolithic integrated device is formed with a cavity within the single substrate and below each micromachined ultrasonic transducer, the cavity extends from the passivation layer to a portion of the inter-layer dielectric;
• wherein the micromachined ultrasonic transducer connected to the electronic circuitry is built on the single substrate.