Array of capacitive micromachined ultrasonic transducer elements with through wafer via connections

• US 6,430,109 B1
• Filed: 09/21/2000
• Issued: 08/06/2002
• Est. Priority Date: 09/30/1999
• Status: Expired due to Term

• Current Assignee: Board of Trustees of the Leland Stanford Junior University (Stanford University)
• Original Assignee: Board of Trustees of the Leland Stanford Junior University (Stanford University)
• Inventors: Jin, Xuecheng, Degertekin, F. Levent, Khuri-Yakub, Butrus T., Calmes, Sam
• Primary Examiner(s): Pihulic, Daniel T.
• Application Number:
  US09/667,203
• Time in Patent Office: 684 Days
• Field of Search: 367/181, 367/174, 367/163
• US Class Current: 367/181
• CPC Class Codes: B06B 1/0292 Electrostatic transducers, e.g. electret-type
• CPC Class Codes: H01L 21/76898 formed through a semiconductor substrate
• CPC Class Codes: H01L 2224/05568 the whole external layer protruding from the surface
• CPC Class Codes: H01L 2224/05573 Single external layer
• CPC Class Codes: H01L 2224/05599 Material
• CPC Class Codes: H01L 2224/131 with a principal constituent of the material being a metal or a metalloid, e.g. boron [B], silicon [Si], germanium [Ge], arsenic [As], antimony [Sb], tellurium [Te] and polonium [Po], and alloys thereof
• CPC Class Codes: H01L 2224/16145 the bodies being stacked
• CPC Class Codes: H01L 23/481 Internal lead connections, e.g. via connections, feedthrough structures
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/014 Solder alloys

Abstract

There is described a cMUT array with transducer elements which include a plurality of cells with membranes formed on one surface of a wafer. Voltages applied between said spaced electrodes drive said membranes. The voltages applied to said electrodes are applied from the opposite surface of the wafer through the wafer and through vias formed in the wafer.

Claims

1. An ultrasonic transducer array comprising a plurality of cMUT elements formed on one surface of a wafer, said cMUT elements including transducer cells having a membrane, a first electrode comprising a metal layer overlying said membranes,

a second electrode spaced from the first electrode,

vias extending through said wafer for connecting to one of the electrodes from the opposite surface of the wafer, and

means for connecting through the wafer to the other electrode.

2. An ultrasonic transducer element comprising a substrate and a plurality of cells, each including a membrane, formed in the surface of said substrate with an electrode for exciting said cell membranes and another electrode spaced from the first membrane whereby a voltage can be applied between said electrodes characterized in that electrical connection is made to one of said electrodes through said substrate and electrical connection is made to said the other of electrodes through a conductor formed in a via extending through said substrate.

3. An ultrasonic transducer element as in claim 2 in which one of the electrodes is the upper surface of the substrate.

4. An ultrasonic transducer element as in claim 2 in which one of said electrodes is a polysilicon layer and said connection through the via is polysilicon.

5. An ultrasonic transducer element as in claim 2 in which the electrical connection through said via is metallic.

6. An array comprising a plurality of transducer elements formed on one surface of a semiconductor wafer,

a first electrode connected to said transducer element,

a second electrode spaced from the first electrode connected to said transducer element,

a conductor insulated from and extending through a via in said wafer for connecting to one of the electrodes from the opposite surface of the wafer, and

means for connecting through the wafer to the other electrode.

7. An array as in claim 6 in which the electrical connection through said via comprises a metallic layer separated from the wafer by an oxide layer.

8. A transducer including at least one active element having at least two electrodes formed on one surface of a semiconductor substrate, means electrically connecting to one of said electrodes from the other surface through the substrate, and means extending through vias formed in said substrate for providing an electrical connection from the other surface of the substrate to the other of said electrodes.

9. A transducer as in claim 8 in which the means extending through the via is semiconductive material.

10. A transducer as in claim 8 in which the means extending through the via is a metallic layer separated from the semiconductor substrate.

11. Transducers disposed on one surface of a semiconductor substrate and means for providing electrical connections to said transducers from the other surface of the substrate comprising vias formed in said substrate extending between said surfaces an oxide layer on the surface of the vias and a conductor formed on the oxide layer in the vias to provide the electrical connection to said transducers.

12. Transducers as in claim 11 in which the conductor is a metal.