PRESSURE PORT FOR ULTRASONIC TRANSDUCER ON CMOS SENSOR
Micromachined ultrasonic transducers having pressure ports are described. The micromachined ultrasonic transducers may comprise flexible membranes configured to vibrate over a cavity. The cavity may be sealed, in some instances by the membrane itself. A pressure port may provide access to the cavity, and thus control of the cavity pressure. In some embodiments, an ultrasound device including an array of micromachined ultrasonic transducers is provided, with pressure ports for at least some of the ultrasonic transducers. The pressure ports may be used to control pressure across the array.
1 . An ultrasound device, comprising:
an ultrasonic transducer, comprising a substrate and a membrane, wherein the substrate and membrane are positioned with a sealed cavity between them; and
an access hole through the membrane and configured to provide access to the sealed cavity.
2 . The ultrasound device of claim 1 , wherein the substrate is bonded with an integrated circuit substrate comprising integrated circuitry.
3 . The ultrasound device of claim 1 , wherein the substrate comprises integrated circuitry.
4 . The ultrasound device of claim 1 , wherein the access hole is sealed at one end.
5 . The ultrasound device of claim 4 , wherein the access hole is sealed at the one end with a metal.
6 . The ultrasound device of claim 4 , wherein the access hole is substantially free of solid material.
7 . The ultrasound device of claim 4 , wherein the access hole comprises a void.
8 . The ultrasound device of claim 7 , wherein the void is filled with a gas.
9 . The ultrasound device of claim 1 , wherein the access hole projects substantially perpendicular to a long axis of the sealed cavity.
10 . The ultrasound device of claim 1 , wherein the access hole comprises a turn.
11 . The ultrasound device of claim 10 , wherein the access hole comprises a 90-degree turn.
12 . The ultrasound device of claim 1 , wherein the access hole comprises a bend.
13 . A micromachined ultrasonic transducer, comprising:
a sealed cavity; and
a pressure port configured to control a pressure of the sealed cavity.
14 . The micromachined ultrasonic transducer of claim 13 , wherein the pressure port comprises an in-plane portion and a substantially perpendicular portion.
15 . The micromachined ultrasonic transducer of claim 13 , wherein the substantially perpendicular portion is thinner than the in-plane portion.
16 . The micromachined ultrasonic transducer of claim 13 , wherein the pressure port is part of a channel interconnecting two cavities including the sealed cavity.
17 . The micromachined ultrasonic transducer of claim 13 , wherein the pressure port comprises a 90-degree bend.
18 . The micromachined ultrasonic transducer of claim 13 , wherein the pressure port is sealed by a metal.
19 . The micromachined ultrasonic transducer of claim 13 , wherein the micromachined ultrasonic transducer comprises at least one of a capacitive micromachined ultrasonic transducer and a piezoelectric micromachined ultrasonic transducer.
20 . The micromachined ultrasonic transducer of claim 13 , wherein the micromachined ultrasonic transducer is disposed in a handheld ultrasound probe.