Ultrasonic transducer

Abstract

Systems and techniques are provided for an ultrasonic transducer. A substrate may include a main cavity, a secondary cavity, and a channel. The main cavity may have a greater depth than the secondary cavity. The secondary cavity may have a greater depth than channel. A first step may be formed where the main cavity and the secondary cavity overlap. A second step may be formed where the secondary cavity and the main cavity overlap. An electromechanically active device may be attached to the substrate at the first step and the second step such that a free end of the electromechanically active device is suspended over the main cavity. A membrane section may be bonded to the substrate such that the membrane covers the main cavity and the secondary cavity and is bonded to the free end of the electromechanically active.

1 . An electromechanical transducer array comprising:
 a substrate comprising two main cavities;   two electromechanically active devices attached to the substrate such that a free end of a first of the two electromechanically active device is suspended over a bottom of a first of the two main cavities and a free end of a second of the two electromechanically active device is suspended over a bottom of a second of the two main cavities;   a membrane bonded to the substrate such that a first membrane section covers the first of the two main cavities and a second membrane section covers a second of the two main cavities, the first membrane section bonded to the first of the two electromechanically active devices and the second membrane section bonded to the second of the two electromechanically active devices.   
     
     
         2 . The electromechanical transducer array of  claim 1 , further comprising a PCB bonded to the substrate. 
     
     
         3 . The electromechanical transducer array of  claim 2 , further comprising a rigid mass bonded to the substrate or the PCB. 
     
     
         4 . The electromechanical transducer array of  claim 1 , wherein the substrate further comprises a secondary cavity, and wherein a first step is formed at a location between the secondary cavity and the first of the two main cavities. 
     
     
         5 . The electromechanical transducer array of  claim 1 , wherein the substrate further comprises a channel, and wherein a second step is formed at a location between the channel and the second main cavity. 
     
     
         6 . The electromechanical transducer array of  claim 5 , further comprising a first via disposed in the first step and second via disposed in the second step, and wherein the first of the two electromechanically active devices comprises a first electrode bonded to the first via and a second electrode bonded to the second via. 
     
     
         7 . The electromechanical transducer array of  claim 1 , wherein the first membrane section is mechanically isolated from the second membrane section such that the first membrane section and the second membrane section move independently. 
     
     
         8 . An ultrasonic transducer comprising:
 a substrate comprising a main cavity;   an electromechanically active device attached to the substrate such that a free end of the electromechanically active device is suspended over a bottom of the main cavity; and   a membrane section bonded to the substrate and the electromechanically active device.   
     
     
         9 . The ultrasonic transducer of  claim 8 , wherein the electromechanically active device comprises a laminate material. 
     
     
         10 . The ultrasonic transducer of  claim 8 , wherein the electromechanically active device comprises an electrically passive material bonded to an electrically active material. 
     
     
         11 . The ultrasonic transducer of  claim 10 , wherein the electrically active material comprises a piezoceramic. 
     
     
         12 . The ultrasonic transducer of  claim 11 , wherein the substrate further comprises a secondary cavity at least partially overlapping the main cavity, wherein the secondary cavity is shallower than the main cavity. 
     
     
         13 . The ultrasonic transducer of  claim 12 , wherein a first step is formed at a location where the secondary cavity overlaps the main cavity. 
     
     
         14 . The ultrasonic transducer of  claim 13 , wherein the substrate further comprises a channel at least partially overlapping the secondary cavity, wherein the channel is shallower than the secondary cavity. 
     
     
         15 . The ultrasonic transducer of  claim 14 , wherein a second step is formed at a location where the channel overlaps the secondary cavity. 
     
     
         16 . The ultrasonic transducer of  claim 15 , wherein the substrate further comprises a first via disposed in the first step and a second via disposed in the second step. 
     
     
         17 . The ultrasonic transducer of  claim 16 , wherein the electromechanically active device further comprises a first electrode and a second electrode. 
     
     
         18 . The ultrasonic transducer of  claim 16 , wherein the first via and the second via descend through the substrate to make electrical contact with at least one layer of a PCB disposed below the substrate. 
     
     
         19 . The ultrasonic transducer of  claim 17 , wherein the electromechanically active device is attached to the substrate at the first step and the second step such that the first electrode is in electrical contact with the first via and the second electrode is in electrical contact with the second via. 
     
     
         20 . The ultrasonic transducer of  claim 8 , wherein the membrane section is bonded to the substrate around the main cavity such that the membrane section covers the main cavity. 
     
     
         21 . The ultrasonic transducer of  claim 8 , wherein the membrane is bonded to the electromechanically active device at the free end of the electromechanically active device such that vibration of the electromechanically active device at ultrasonic frequency causes the membrane section to vibrate at ultrasonic frequencies. 
     
     
         22 . The ultrasonic transducer of  claim 15 , wherein the substrate further comprises a first trench and a second trench, the first trench creating a flat riser for the first step and the second trench creating a flat riser for the second step. 
     
     
         23 . The ultrasonic transducer of  claim 8 , wherein the substrate comprises aluminum, copper, silicon/aluminum alloy, or silicon. 
     
     
         24 . The ultrasonic transducer of  claim 8 , further comprising a rigid mass bonded to the ultrasonic transducer. 
     
     
         25 . The ultrasonic transducer of  claim 24 , wherein the rigid mass is bonded to a PCB which is bonded to the substrate.