	US 11,988,640 B2
	Bottom electrode material stack for micromachined ultrasonic transducer devices
Jianwei Liu, Fremont, CA (US); Lingyun Miao, Fremont, CA (US); and Victor L. Pushparaj, Milpitas, CA (US)
Assigned to BFLY OPERATIONS, INC., Burlington, MA (US)
Filed by BFLY OPERATIONS, INC., Burlington, MA (US)
Filed on Mar. 10, 2021, as Appl. No. 17/198,174.
Claims priority of provisional application 62/988,290, filed on Mar. 11, 2020.
Prior Publication US 2021/0285917 A1, Sep. 16, 2021
Int. Cl. G01N 29/24 (2006.01); A61B 8/00 (2006.01); B06B 1/02 (2006.01); B81B 7/00 (2006.01); B81C 1/00 (2006.01)

CPC G01N 29/2406 (2013.01) [A61B 8/4483 (2013.01); B06B 1/0292 (2013.01); B81B 7/007 (2013.01); B81C 1/00166 (2013.01)]

14 Claims

1. An ultrasonic transducer device, comprising:

a bottom electrode layer of a transducer cavity disposed over a substrate, the bottom electrode further comprising:

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;

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 separate at least two discrete layers of the second type metal; and

a bottom cavity layer formed on the bottom electrode layer, the bottom cavity layer including a chemical vapor deposition (CVD) SiO₂layer and an atomic layer deposition (ALD) Al₂O₃layer formed on the SiO₂layer.