Ultrasonic Transducer and Method of Fabricating an Ultrasonic Transducer

Abstract

An ultrasonic transducer that includes a delay line, an active piezoelectric element, and interposing metal conductive layer between the delay line and active piezoelectric element. The delay line and active piezoelectric element are joined so that ultrasonic waves may be coupled from the active piezoelectric element into the delay line or from the delay line into the active piezoelectric element. A via is formed, using a milling operation, in the active piezoelectric element to expose the edge of the interposing metal conductive layer between the delay line and active piezoelectric element. A conductive layer makes electrical contact between the interposing metal conductive layer and the surface of the active piezoelectric element to allow an electrical connection to be made from the surface of the active piezoelectric element to the interposing metal conductive layer.

1 - 7 . (canceled) 
     
     
         8 . A method of producing an ultrasonic transducer, the method comprising the steps of:
 providing a delay line substrate;   providing a piezoelectric substrate as an active transducer element;   depositing a first metal layer on the delay line substrate;   depositing a second metal layer and the piezoelectric substrate;   bonding the delay line substrate to the piezoelectric substrate to form a stack and to facilitate coupling ultrasonic waves from the piezoelectric element into the delay line or from the delay line into the piezoelectric element;   milling the piezoelectric substrate to expose a portion of at least one of the first metal layer and the second metal layer to allow electrical contact;   depositing a first patterned electrode on the exposed portion to allow external electrical connection to the at least one of the first metal layer and the second metal layer; and   depositing a second patterned electrode on the piezoelectric element, the second patterned electrode defining an active area of the ultrasonic transducer and configured to electrically connect externally.   
     
     
         9 . The method of  claim 8 , further comprising:
 milling the piezoelectric substrate at a plurality of locations; and   partitioning the stack through at least one of the plurality of locations to create individual ultrasonic transducers.   
     
     
         10 . The method of  claim 9 , wherein the partitioning includes core drilling through the delay line substrate of the at least one of the plurality of locations. 
     
     
         11 . A method of producing an ultrasonic transducer, the method comprising the steps of:
 providing a delay line substrate;   providing a piezoelectric substrate as an active transducer element;   depositing a metal layer on either the delay line substrate or the piezoelectric substrate;   bonding the delay line substrate to the piezoelectric substrate such that the deposited metal layer is between the delay line substrate and the piezoelectric substrate to form a stack and to facilitate coupling ultrasonic waves from the piezoelectric element into the delay line or from the delay line into the piezoelectric element;   milling the piezoelectric substrate to expose a portion of at least one of the first metal layer and the second metal layer to allow electrical contact;   depositing a first patterned electrode on the exposed portion to allow external electrical connection to the at least one of the first metal layer and the second metal layer; and   depositing a second patterned electrode on the piezoelectric element, the second patterned electrode defining an active area of the ultrasonic transducer and configured to electrically connect externally.   
     
     
         12 . The method of  claim 11 , wherein milling the piezoelectric substrate occurs at a plurality of locations and the method of  claim 9  further comprises partitioning the stack through at least one of the plurality of locations to create individual ultrasonic transducers. 
     
     
         13 . The method of  claim 12 , wherein the partitioning includes core drilling through the delay line substrate of the at least one of the plurality of locations. 
     
     
         14 . The method of  claim 11 , wherein milling the piezoelectric substrate forms a via tapering to a depth. 
     
     
         15 . The method of  claim 11 , wherein milling the piezoelectric substrate forms an annular via including two side walls extending a full depth of the via, and depositing the first patterned electrode deposits the first patterned electrode on a radially inward one of the two side walls. 
     
     
         16 . The method of  claim 11 , wherein milling the piezoelectric substrate forms an annular via including two side walls extending a full depth of the via, and depositing the first patterned electrode deposits the first patterned electrode on both of the two side walls. 
     
     
         17 . The method of  claim 16 , wherein depositing the first patterned electrode deposits the first patterned electrode discontinuously between the two side walls.