Electrical generator or motor structure – Non-dynamoelectric – Piezoelectric elements and devices
Patent
1990-06-25
1992-11-03
Budd, Mark O.
Electrical generator or motor structure
Non-dynamoelectric
Piezoelectric elements and devices
310324, 310334, 310338, 310800, H01L 4108
Patent
active
051608707
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 water 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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Carson Paul L.
Fitting Dale W.
Robinson Andrew L.
Terry, Jr. Fred L.
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