Ultrasound fingerprint sensing and sensor fabrication

Patent metadata

Field	Value
Publication number	US-11263422-B2
Application number	US-201815968420-A
Country	US
Kind code	B2
Filing date	May 1, 2018
Priority date	May 1, 2017
Publication date	Mar 1, 2022
Grant date	Mar 1, 2022

Abstract

Disclosed are systems, devices and methods for providing fingerprint sensors based on ultrasound imaging techniques in electronic devices and fabrication techniques for producing ultrasound-based fingerprint sensors. In some aspects, an ultrasound fingerprint sensor device includes an intermediate layer coupled to a base chip including an integrated circuit having conducive contacts at a surface of the base chip, the intermediate layer including an insulation layer formed on the base chip and a corresponding array of channeling electrode structures coupled to the conductive contacts and passing through the insulation layer, in which the channeling electrodes terminate at or above a top surface of the insulation layer to provide bottom electrodes; a plurality of ultrasonic transducer elements including an acoustic transducer material coupled to the bottom electrodes; and a plurality of top electrodes positioned on the ultrasonic transducer elements.

First claim

What is claimed is:

1. An ultrasound fingerprint sensor device, comprising:
an intermediate layer coupled to a base chip including an integrated circuit having conductive contacts at a surface of the base chip, the intermediate layer including an insulation layer formed on the base chip and a corresponding array of channeling electrode structures coupled to the conductive contacts and passing through the insulation layer, wherein the channeling electrode structures terminate at or above a top surface of the insulation layer to provide bottom electrodes, wherein each of the bottom electrodes is associated with a different conductive contact of the conductive contacts and a different channeling electrode structure of the channeling electrode structures;
a plurality of ultrasonic transducer elements, wherein each of the plurality of ultrasonic transducer elements is coupled to a different bottom electrode of the bottom electrodes and each of the plurality of ultrasonic transducer elements comprises acoustic transducer material; and
a plurality of top electrodes positioned on the plurality of ultrasonic transducer elements, wherein each of the plurality of top electrodes is connected to a different ultrasonic transducer element of the plurality of ultrasonic transducer elements.

2. The device of claim 1 , further comprising:
a filler material that is filled in gaps between the ultrasonic transducer elements over the insulation layer.

3. The device of claim 2 , wherein the filler material includes one or more of an epoxy or a gel.

4. The device of claim 1 , wherein the acoustic transducer material includes a piezeoelectric crystal including lead zirconate titanate (PZT), aluminum nitride (AlN), gallium phosphate, quartz, tourmaline, lead magnesium niobate-lead titanate (PMN-PT).

5. The device of claim 1 , wherein the base chip includes a CMOS device.

6. The device of claim 1 , wherein the insulation layer includes silicon oxide.

7. The device of claim 1 , wherein the plurality of ultrasonic transducer elements include a two-dimensional array of transducer elements, wherein each transducer element of the array is positioned above a respective bottom electrode.

8. The device of claim 1 , wherein the plurality of ultrasonic transducer elements include a one-dimensional array of transducer elements positioned above a group of the bottom electrodes.

9. The device of claim 1 , wherein the ultrasound fingerprint sensor device is operable to transmit an acoustic probe signal toward a target volume and receive a return acoustic signal reflected from the target volume at the plurality of ultrasonic transducer elements, wherein the top electrodes are coupled to a driver circuit to control actuation of the ultrasonic transducer elements to generate the acoustic probe signal, and wherein ultrasonic transducer elements are coupled to a receiver circuit to process the received return acoustic signal.

10. The device of claim 1 , wherein the ultrasound fingerprint sensor device is operable to transmit an acoustic probe signal toward a target volume, wherein the top electrodes are coupled to a driver circuit to control actuation of the ultrasonic transducer elements to generate the acoustic probe signal, the device further comprising:
a plurality of second ultrasonic transducer elements including an acoustic transducer material positioned underneath the base chip; and
a second intermediate layer coupled to a second base chip including a second integrated circuit having second conducive contacts at a surface of the second base chip, the second intermediate layer including a second insulation layer formed on the second base chip and a corresponding array of second channeling electrode structures coupled to the second conductive contacts and passing through the second insulation layer, wherein the second channeling electrode structures terminate at or above a top surface of the second insulation layer to provide second bottom electrodes, and wherein the second electrodes are coupled to the second ultrasonic transducer elements.

11. A method for fabricating an ultrasound fingerprint sensor device, the method comprising:
producing an intermediary protective structure including an array of bottom electrodes and an insulation layer on a base chip;
forming a layer of an acoustic transducer material on the intermediary protective structure;
producing transducer elements over the intermediary protective structure by dicing or etching the formed transducer material layer to create the transducer elements, wherein the insulation layer includes a thickness such that portions of the intermediary protective structure incur loss without any damage occurring to the underlying base chip during the dicing or etching the formed layer of the acoustic transducer material, wherein each of the transducer elements is coupled to a different bottom electrode of the bottom electrodes and each of the transducer elements comprises the acoustic transducer material; and
producing top electrodes on the produced transducer elements, wherein each of the top electrodes is connected to a different transducer element of the transducer elements.

12. The method of claim 11 , wherein the insulation layer includes silicon oxide.

13. The method of claim 11 , wherein the acoustic transducer material includes a piezeoelectric crystal including lead zirconate titanate (PZT), aluminum nitride (AlN), gallium phosphate, quartz, tourmaline, lead magnesium niobate-lead titanate (PMN-PT).

14. The method of claim 11 , wherein the base chip includes a CMOS device.

15. The method of claim 11 , further comprising:
adding a filler material in gaps between the produced transducer elements over the insulation layer.

16. The method of claim 15 , wherein the filler material includes one or more of an epoxy or a gel.

17. The method of claim 11 , wherein the producing the intermediary protective structure includes:
forming the insulation layer on the base chip;
etching channels through the insulation layer at a position above conductive contacts of the base chip; and
depositing conductive material in the etched channels to form the bottom electrodes,
wherein the bottom electrodes include an interface surface positioned at or above a top surface of the insulation layer.

18. The method of claim 11 , wherein the forming the layer of the acoustic transducer material includes bonding the layer including one or more of gluing or soldering.

19. The method of claim 11 , wherein the layer of acoustic transducer material is formed as a single piece or as multiple pieces.

20. The method of claim 19 , wherein the forming the layer includes preparing one or both of the top and bottom surfaces of the acoustic transducer material for electrode coatings including producing a pre-coated electrode pattern on the layer of acoustic transducer material.

21. The method of claim 11 , wherein the produced transducer elements are diced or etched as a one-dimensional row or column of the transducer elements.

22. The method of claim 11 , wherein the produced transducer elements are diced or etched as a two-dimensional array of discrete transducer elements over the bottom electrodes.

23. The method of claim 11 , further comprising:
filling gaps in the diced or etched regions of the acoustic transducer material with a filling material.

24. The method of claim 11 , wherein the producing the top electrodes includes coating a conductive ma

Assignees

• Shenzhen Goodix Tech Co Ltd

Inventors

• He Yi
• Pi Bo

Classifications

• G06V40/1306 Primary

  non-optical, e.g. ultrasonic or capacitive sensing · CPC title

• B06B2201/70

  Specific application · CPC title

• B06B1/0207

  Driving circuits (specially adapted for particular applications, see the relevant subclass, e.g. G01; circuits for steering transducer arrays G10K11/34; basic circuits H03) · CPC title

• B06B1/0622 Primary

  on one surface · CPC title

• G01S7/52079

  Constructional features (constructional features of transducers B06B; mounting transducers G10K11/00; constructional features of ultrasonic medical diagnostic devices A61B8/44) · CPC title