ULTRASONIC RECEIVER WITH COATED PIEZOELECTRIC LAYER

• US 20140355387A1
• Filed: 02/07/2014
• Published: 12/04/2014
• Est. Priority Date: 06/03/2013
• Status: Abandoned Application

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Kitchens, Jack Conway II, Schneider, John Keith, Gojevic, Stephen Michael
• Application Number:
  US14/175,876
• Publication Number:
  US 20140355387A1
• Time in Patent Office: Days
• US Class Current: 367/137
• CPC Class Codes: A61B 5/1172 using fingerprinting
• CPC Class Codes: B06B 1/0688 with foil-type piezoelectric elements, e.g. PVDF
• CPC Class Codes: G01H 1/00 Measuring characteristics of vibrations in solids by using direct conduction to the detector G01H9/00, G01H11/00 take precedence
• CPC Class Codes: G01H 11/08 using piezoelectric devices
• CPC Class Codes: G06V 40/1306 non-optical, e.g. ultrasonic or capacitive sensing
• CPC Class Codes: H04R 17/005 using a piezoelectric polymer

Abstract

This disclosure provides systems, methods and apparatus related to an ultrasonic receiver for detecting ultrasonic energy received at a first surface of the ultrasonic receiver. The ultrasonic receiver includes an array of pixel circuits disposed on a substrate, each pixel circuit in the array including at least one thin film transistor (TFT) element and having a pixel input electrode electrically coupled to the pixel circuit. The ultrasonic receiver is fabricated by forming a piezoelectric layer so as to be in electrical contact with the pixel input electrodes. Forming the piezoelectric layer includes coating a solution containing a polymer onto the array of pixel circuits, crystallizing the polymer to form a crystallized polymer layer and poling the crystallized polymer layer.

Claims

1. An apparatus comprising:

an ultrasonic receiver for detecting ultrasonic energy received at a first surface of the ultrasonic receiver, the ultrasonic receiver including an array of pixel circuits disposed on a substrate, each pixel circuit in the array including at least one thin film transistor (TFT) element and having a pixel input electrode electrically coupled to the pixel circuit, wherein the ultrasonic receiver is fabricated by;

forming a piezoelectric layer so as to be in electrical contact with the pixel input electrodes, wherein forming the piezoelectric layer includes;

coating a solution containing a polymer onto the array of pixel circuits;

crystallizing the polymer to form a crystallized polymer layer; and

poling the crystallized polymer layer.

2. The apparatus of claim 1, wherein the pixel input electrode is formed from a conductive film.

3. The apparatus of claim 1, wherein forming the piezoelectric layer includes coating an adhesion promoter onto the array of pixel circuits.

4. The apparatus of claim 1, wherein coating the solution containing the polymer is performed by spin coating, slot coating, dipping, dispensing, spraying, or another coating process.

5. The apparatus of claim 1, wherein the polymer includes a ferroelectric polymer.

6. The apparatus of claim 1, wherein the polymer has a characteristic Curie temperature and a melting point, and crystallizing the polymer includes baking the polymer at a temperature between the Curie temperature and the melting point for at least one hour.

7. The apparatus of claim 1, wherein a conductive material is applied to electrically short terminals of the pixel circuits to ground prior to the poling.

8. The apparatus of claim 7, wherein the conductive material is a conductive rubber or a conductive ink.

9. The apparatus of claim 1, further including a receiver bias electrode deposited on the piezoelectric layer.

10. The apparatus of claim 9, wherein the receiver bias electrode includes a first sublayer of copper and a second sublayer of nickel.

11. The apparatus of claim 10, wherein the first sublayer is about 150 angstroms thick and the second sublayer of nickel is about 850 angstroms thick.

12. An apparatus comprising:

means for detecting received ultrasonic energy wherein;

an array of pixel circuits is disposed on a substrate, each pixel circuit in the array including at least one thin film transistor (TFT) element and having a pixel input electrode electrically coupled to the pixel circuit; and

a piezoelectric layer is formed so as to be in electrical contact with the pixel input electrodes by;

coating a solution containing a polymer onto the array of pixel circuits;

crystallizing the polymer to form a crystallized polymer layer; and

poling the crystallized polymer layer.

13. The apparatus of claim 12, wherein coating the solution containing the polymer is performed by spin coating, slot coating, dipping, dispensing, spraying, or another coating process.

14. The apparatus of claim 12, wherein the polymer includes a ferroelectric polymer.

16. The method of claim 12, wherein the pixel input electrode is formed from a conductive film.

17. The method of claim 12, wherein poling includes applying an electric field with a field strength between 150 and 200 volts per micron through the polymer layer.

15. A method for fabricating an ultrasonic receiver configured to detect ultrasonic energy received at a first surface of the ultrasonic receiver, the ultrasonic receiver including an array of pixel circuits disposed on a substrate, each pixel circuit in the array including at least one thin film transistor (TFT) element and having a pixel input electrode electrically coupled to the pixel circuit, the method comprising:

forming a piezoelectric layer so as to be in electrical contact with the pixel input electrodes, wherein forming the piezoelectric layer includes;

coating a solution containing a polymer onto the array of pixel circuits;

crystallizing the polymer to form a crystallized polymer layer; and

poling the crystallized polymer layer.

18. A computer-readable storage medium having stored thereon instructions which, when executed by a computing system, cause the computing system to perform operations for fabricating an ultrasonic receiver configured to detect ultrasonic energy received at a first surface of the ultrasonic receiver, the ultrasonic receiver including an array of pixel circuits disposed on a substrate, each pixel circuit in the array including at least one thin film transistor (TFT) element and having a pixel input electrode electrically coupled to the pixel circuit, the operations comprising

forming a piezoelectric layer so as to be in electrical contact with the pixel input electrodes, wherein forming the piezoelectric layer includes:

coating a solution containing a polymer onto the array of pixel circuits;

crystallizing the polymer to form a crystallized polymer layer; and

poling the crystallized polymer layer.

19. The computer-readable storage medium of claim 18, wherein forming the piezoelectric layer includes coating an adhesion promoter onto the array of pixel circuits.

20. The computer-readable storage medium of claim 18, wherein a conductive material is applied to electrically short terminals of the pixel circuits to ground prior to the poling.

21. An apparatus comprising:

an ultrasonic transmitter;

a platen; and

an ultrasonic receiver disposed between the ultrasonic transmitter and the platen, the ultrasonic receiver including an array of pixel circuits disposed on a substrate, each pixel circuit in the array including a thin film transistor (TFT) element and having a pixel input electrode electrically coupled to the pixel circuit, the ultrasonic receiver being configured to detect ultrasonic energy reflected from an object in contact with the platen, the reflected ultrasonic energy resulting from interaction of ultrasonic energy emitted by the ultrasonic transmitter and the object, the ultrasonic receiver including a piezoelectric layer disposed between the array of pixel circuits and the platen, wherein;

the piezoelectric layer is in electrical contact with the pixel input electrodes; and

the piezoelectric layer is formed by;

coating a solution containing a polymer onto the array of pixel circuits;

crystallizing the polymer to form a crystallized polymer layer; and

poling the crystallized polymer coating.

22. An apparatus comprising:

an ultrasonic transmitter;

a platen; and

means, disposed between the ultrasonic transmitter and the platen, for detecting ultrasonic energy reflected from an object in contact with the platen, the reflected ultrasonic energy resulting from interaction of ultrasonic energy emitted by the ultrasonic transmitter and the object, wherein;

an array of pixel circuits is disposed on a substrate, each pixel circuit in the array including a thin film transistor (TFT) element and having a pixel input electrode electrically coupled to the pixel circuit; and

a piezoelectric layer is disposed between the array of pixel circuits and the platen, such that the piezoelectric layer is in electrical contact with the pixel input electrodes and is formed by;

coating a solution containing a polymer onto the array of pixel circuits;

crystallizing the polymer to form a crystallized polymer layer; and

poling the crystallized polymer coating.

23. A method comprising:

forming a piezoelectric layer by;

coating a solution containing a polymer onto an array of pixel circuits;

crystallizing the polymer to form a crystallized polymer layer; and

poling the crystallized polymer coating; and

disposing an ultrasonic receiver between an ultrasonic transmitter and a platen, the ultrasonic receiver being configured to detect ultrasonic energy reflected from an object in contact with the platen, the reflected ultrasonic energy resulting from interaction of ultrasonic energy emitted by the ultrasonic transmitter and the object, the ultrasonic receiver including;

an array of pixel circuits disposed on a substrate; and

the piezoelectric layer disposed between the array of pixel circuits and the platen;

wherein;

each pixel circuit in the array includes a thin film transistor (TFT) element and has a pixel input electrode electrically coupled to the pixel circuit, and

the piezoelectric layer is in electrical contact with the pixel input electrodes.

24. A computer-readable storage medium having stored thereon instructions which, when executed by a computing system, cause the computing system to perform operations, the operations comprising:

forming a piezoelectric layer by;

coating a solution containing a polymer onto an array of pixel circuits;

crystallizing the polymer to form a crystallized polymer layer; and

poling the crystallized polymer coating; and

disposing an ultrasonic receiver between an ultrasonic transmitter and a platen, the ultrasonic receiver being configured to detect ultrasonic energy reflected from an object in contact with the platen, the reflected ultrasonic energy resulting from interaction of ultrasonic energy emitted by the ultrasonic transmitter and the object, the ultrasonic receiver including;

an array of pixel circuits disposed on a substrate; and

the piezoelectric layer disposed between the array of pixel circuits and the platen;

wherein;

each pixel circuit in the array includes a thin film transistor (TFT) element and has a pixel input electrode electrically coupled to the pixel circuit, and

the piezoelectric layer is in electrical contact with the pixel input electrodes.

25. An apparatus comprising:

an ultrasonic receiver for detecting ultrasonic energy received at a first surface of the ultrasonic sensor, the ultrasonic sensor including an array of pixel circuits disposed on a substrate, each pixel circuit in the array including at least one thin film transistor (TFT) element and having a pixel input electrode electrically coupled to the pixel circuit, and a piezoelectric layer in electrical contact with the pixel input electrodes, wherein the piezoelectric layer includes a poled crystallized polymer layer.

26. An apparatus comprising:

means for detecting ultrasonic energy received at a first surface of the ultrasonic sensor, the ultrasonic sensor including an array of pixel circuits disposed on a substrate, each pixel circuit in the array including at least one thin film transistor (TFT) element and having a pixel input electrode electrically coupled to the pixel circuit, and a piezoelectric layer in electrical contact with the pixel input electrodes, wherein the piezoelectric layer includes a poled crystallized polymer layer.

27. A method comprising:

detecting ultrasonic energy received at a first surface of the ultrasonic sensor, the ultrasonic sensor including an array of pixel circuits disposed on a substrate, each pixel circuit in the array including at least one thin film transistor (TFT) element and having a pixel input electrode electrically coupled to the pixel circuit, and a piezoelectric layer in electrical contact with the pixel input electrodes, wherein the piezoelectric layer includes a poled crystallized polymer layer.

28. A computer-readable storage medium having stored thereon instructions which, when executed by a computing system, cause the computing system to perform operations, the operations comprising:

detecting ultrasonic energy received at a first surface of the ultrasonic sensor, the ultrasonic sensor including an array of pixel circuits disposed on a substrate, each pixel circuit in the array including at least one thin film transistor (TFT) element and having a pixel input electrode electrically coupled to the pixel circuit, and a piezoelectric layer in electrical contact with the pixel input electrodes, wherein the piezoelectric layer includes a poled crystallized polymer layer.