US Patent 11988640 Bottom electrode material stack for micromachined ultrasonic transducer devices

An ultrasonic transducer device includes a bottom electrode layer of a transducer cavity disposed over a substrate. The bottom electrode layer includes a bottom layer of a first type metal; a top layer of the first type metal; a second type metal disposed between the bottom layer and the top layer; and at least one intermediate layer of the first type metal disposed between the bottom layer and the top layer, the at least one intermediate layer configured so as to define at least two discrete layers of the second type metal.