High frequency cmos ultrasonic transducer

Abstract

In described examples of a CMOS IC, an ultrasonic transducer having terminals is formed on a substrate of the IC. CMOS circuitry having ultrasonic signal terminals is formed on the substrate. At least one metal interconnect layer overlies the ultrasonic transducer and the CMOS circuitry. The at least one metal interconnect layer connects the CMOS circuitry ultrasonic signal terminals to the terminals of the ultrasonic transducer.

What is claimed is: 
     
         1 . A complementary metal oxide semiconductor (CMOS) integrated circuit (IC) comprising:
 a substrate;   an ultrasonic transducer formed on the substrate, the ultrasonic transducer having signal terminals;   CMOS circuitry formed on the substrate, the circuitry having ultrasonic signal terminals; and   at least one metal interconnect layer overlying the ultrasonic transducer and the CMOS circuitry, wherein the at least one metal interconnect layer connects the ultrasonic signal terminals to the terminals of the ultrasonic transducer.   
     
     
         2 . The CMOS IC of  claim 1 , wherein the ultrasonic transducer comprises:
 a linear array of ferroelectric capacitors (FeCaps) each having a respective length and a respective width arranged in a single row on the substrate, such that the length of each of the array of FeCaps is perpendicular to an axis of the row;   a waveguide portion of the array of FeCaps positioned in the middle of the row each having a respective first width;   a reflector portion of the array of FeCaps positioned at a first end of the row, wherein each FeCap in the reflector portion has a respective width that is larger than the first width; and   a radiator portion of the array of FeCaps positioned at a second end of the row opposite the first end, wherein each FeCap in the radiator portion has a respective width that is smaller than the first width.   
     
     
         3 . The CMOS IC of  claim 2 , further comprising mold compound encapsulating the substrate, wherein an opening is provided in the mold compound to expose a portion of the linear array of FeCaps. 
     
     
         4 . The CMOS IC of  claim 2 , wherein the respective width of the FeCaps in the radiator portion gradually reduces from the first width to a second width. 
     
     
         5 . The CMOS IC of  claim 2 , wherein each of the array of FeCaps has a respective first conductive plate and a respective second conductive plate with a ferroelectric material between the first and second plates. 
     
     
         6 . The CMOS IC of  claim 5 , wherein the first conductive plate of at least one of the FeCaps in the radiator portion is connected to at least two contact pads, the first conductive plate of at least one of the FeCaps in the radiator portion is connected to only one contact pad, and the first conductive plate of at least one of the FeCaps in the radiator portion is not connected to a contact pad. 
     
     
         7 . The CMOS IC of  claim 6 , wherein at least one of the FeCaps in the radiator portion does not have a first conductive plate. 
     
     
         8 . The CMOS IC of  claim 2 , wherein the respective width of FeCaps in the reflector portion ranges within 10% to 50% larger than the first width. 
     
     
         9 . The CMOS IC of  claim 8 , wherein the FeCaps in the reflector portion have a respective width that progressively increases. 
     
     
         10 . A method of operating an ultrasonic transmitter, the method comprising:
 applying an ultrasonic signal to a waveguide portion of ferroelectric capacitors (FeCaps); the waveguide portion of FeCaps located in a middle of a linear array of FeCaps on a semiconductor substrate,   producing an ultrasonic wave in the waveguide portion of FeCaps by piezoelectric operation of the waveguide portion of FeCaps;   reflecting a portion of the ultrasonic wave by a reflector portion of FeCaps, the reflector portion of FeCaps positioned at a first end of the linear array of FeCaps; and   radiating a portion of the ultrasonic wave from a radiating structure formed by portion of the FeCaps positioned at a second end of the linear array of FeCaps opposite the first end of the linear array of FeCaps.   
     
     
         11 . The method of  claim 10 , further comprising propagating the radiated portion of the ultrasonic wave through a radiation medium coupled to the radiating structure. 
     
     
         12 . The method of  claim 10 , further comprising guiding the ultrasonic wave along the waveguide portion of FeCaps by a guided mode of operation produced by the waveguide portion of FeCaps. 
     
     
         13 . The method of  claim 10 , wherein the ultrasonic signal has a frequency within a range of 20-900 MHz.