Ultrasonic image sensing array with acoustical backing
First Claim
1. A micromachined ultrasonic sensing array having a plurality of piezoelectric transducers, each of which generates an electric signal corresponding to a mechanical force acoustically applied thereto, the array comprising:
- a patterned micromachined support substrate;
a composite dielectric diaphragm layer formed on the substrate;
a first plurality of electrically conductive plates spaced from one another and connectable to an external bonding pad and resting on the diaphragm layer, each such plate forming first plate of a distinct one of the transducers;
a plurality of patterned piezoelectric polymer film layers spaced from one another and bonded to the first plurality of electrically conductive plates, said layers of piezoelectric film being responsive to ultrasonic acoustically applied forces;
a second plurality of electrically conductive plates spaced from one another and resting on the piezoelectric polymer film layer, each such plate forming a second plate of a distinct one of the transducers; and
electronic circuit means for detecting analog values of said electric signal generated by said piezoelectric layer in response to an ultrasonic acoustically applied mechanical force.
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Accused Products
Abstract
An ultrasonic sensing array having ultrasonic transducer elements formed on a micromachined single-crystal semiconductor wafer provided with a deep recess under each transducer. Etch-altering dopants are diffused into the wafer to form rimmed support structures for dielectric stress-balanced elements. Composite dielectric layers are grown on both surfaces of the wafer. One composite layer serves as a diaphragm underlying the transducer elements. The other composite layer serves as a mask for etching away the substrate under each transducer element to form the deep recess while leaving the support structures and diaphragm layer. The resulting hollow or recess under each transducer element reduces the parasitic capacitance between the transducer and support substrate. The transducer elements are made by forming conductive bottom plates on the dielectric diaphragm layer, adding a piezoelectric polymer layer and thereafter forming the conductive top plates. The resulting ultrasonic sensors are capable of operation over a wide variety of frequencies with improved sensitivity and decreased acoustic crosstalk between sensor elements, Switching transistors may also be fabricated as part of the patterned semiconductor substrate.
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Citations
21 Claims
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1. A micromachined ultrasonic sensing array having a plurality of piezoelectric transducers, each of which generates an electric signal corresponding to a mechanical force acoustically applied thereto, the array comprising:
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a patterned micromachined support substrate; a composite dielectric diaphragm layer formed on the substrate; a first plurality of electrically conductive plates spaced from one another and connectable to an external bonding pad and resting on the diaphragm layer, each such plate forming first plate of a distinct one of the transducers; a plurality of patterned piezoelectric polymer film layers spaced from one another and bonded to the first plurality of electrically conductive plates, said layers of piezoelectric film being responsive to ultrasonic acoustically applied forces; a second plurality of electrically conductive plates spaced from one another and resting on the piezoelectric polymer film layer, each such plate forming a second plate of a distinct one of the transducers; and electronic circuit means for detecting analog values of said electric signal generated by said piezoelectric layer in response to an ultrasonic acoustically applied mechanical force. - View Dependent Claims (2, 3, 4, 5)
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6. An ultrasonic sensor array having a plurality of piezoelectric transducers, each of which is responsive to ultrasonic forces applied thereto, the array comprising:
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a patterned micromachined support substrate; a diaphragm layer formed on one side of the substrate; a first plurality of electrically conductive plates laterally spaced from one another on a side of the diaphragm layer opposite the substrate, each such plate being associated with a distinct one of the transducers; at least one layer of piezoelectric material bonded to the first plurality of electrically conductive plates, said layer of piezoelectric material being responsive to acoustically applied forces; a second plurality of electrically conductive plates spaced from one another and located on a side of the layer of piezoelectric material opposite the first plurality of electrically conductive plates, each such plate of the second plurality of plates being associated with a distinct one of the transducers; and electronic circuit means for detecting analog values of said electric signal generated by said piezoelectric layer in response to an ultrasonic acoustically applied mechanical force. - View Dependent Claims (7, 8, 9)
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10. An ultrasonic sensor array having a plurality of piezoelectric transducers, each of which is electrically responsive to an ultrasonic force applied thereto, the array comprising:
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a patterned support substrate made of single-crystal semiconductor material and having a plurality of deep recesses therein, one for each transducer; a diaphragm layer formed on one side of the substrate and overlying at least the deep recesses in the support substrate; a plurality of ultrasonic transducers, spaced from one another, each transducer being electrically responsive to an ultrasonic force applied thereto, each transducer including; a first electrically conductive plate resting on the diaphragm layer and overlying a distinct one of the deep recesses in the substrate; a piezoelectric film layer bonded to the first electrically conductive plate; and a second electrically conductive plate bonded to the piezoelectric film layer on a side thereof opposite the first electrically conductive plate of the transducer. - View Dependent Claims (11, 12, 13, 14, 15, 17, 19)
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16. the first and second electrically conductive plates, and the rows of transducers being further arranged in columns having slots between adjacent columns, whereby the columns of first and second electrically conductive plates and thereby the columns of transducers are separately electronically addressable.
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18. An ultrasonic sensor array having a plurality of piezoelectric transducers, each of which is responsive to ultrasonic forces applied thereto, the array comprising:
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a patterned micromachined support substrate; a diaphragm layer formed on one side of the substrate; a first plurality of electrically conductive plates laterally spaced from one another on a side of the diaphragm layer opposite the substrate, each such plate being associated with a distinct one of the transducers; at least one layer of piezoelectric material bonded to the first plurality of electrically conductive plates, said layer of piezoelectric material being responsive to acoustically applied forces; a second plurality of electrically conductive plates spaced from one another and located on a side of the layer of piezoelectric material opposite the first plurality of electrically conductive plates, each such plate of the second plurality of plates being associated with a distinct one of the transducers; electronic circuit means for detecting analog values of said electric signal generated by said piezoelectric layer in response to an ultrasonic acoustically applied mechanical force; and wherein the substrate further comprises a layer of boron diffused region encircling the perimeter of each transducer.
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20. A micromachined ultrasonic sensing array having a plurality of piezoelectric transducers, each of which generates an electric signal corresponding to a mechanical force acoustically applied thereto, the array comprising:
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a patterned micromachined support substrate, the patterned substrate being provided with a plurality of holes which pass entirely through the substrate and extend to the dielectric layer, and wherein each of the holes is substantially similar in area to the first plurality of conductive plates, thereby reducing acoustic coupling between the transducers; a composite dielectric diaphragm layer formed on the substrate; a first plurality of electrically conductive plates spaced from one another an deconnectable to an external bonding pad and resting on the diaphragm layer, each such plate forming a first plate of a distinct one of the transducers; a plurality of patterned piezoelectric polymer film layers spaced from one another and bonded to the first plurality of electrically conduct plates, said layers of piezoelectric film being responsive to ultrasonic acoustically applied forces; a second plurality of electrically conductive plates spaced from one another and resting on the piezoelectric polymer film layer, each such plate forming a second plate of a distinct one of the transducers; and electronic circuit means for detecting analog values of said electric signal generated by said piezoelectric layer in response to an ultrasonic acoustically applied mechanical force.
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21. A micromachined ultrasonic sensing array having a plurality of piezoelectric transducers, each of which generates an electric signal corresponding to a mechanical force acoustically applied thereto, the array comprising:
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a patterned micromachined support substrate, said substrate having a surface with alternating regions of two distinct levels; a composite dielectric diaphragm layer formed on the substrate; a first plurality of electrically conduct plates spaced from one another and connectable to an external bonding pad an resting on the diaphragm layer, each such plate forming a first plate of a distinct one of the transducers adjacent plates of each adjacent transducer being formed on said alternating regions of tow distinct levels; a plurality of patterned piezoelectric polymer film layers spaced from one another and bonded to the first plurality of electrically conductive plates, said layers of piezoelectric film being responsive to ultrasonic acoustically applied forces; a second plurality of electrically conductive plates spaced from one another and resting on the piezoelectric polymer film layer, each such plate forming a second plate of distinct one of the transducers; and electronic circuit means for detecting analog values of said electric signal generated by said piezoelectric layer in response to an ultrasonic acoustically applied mechanical force.
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Specification