Ultrasonic transducer, method for manufacturing ultrasonic transducer, ultrasonic finger recognition sensor and electronic device

1. An ultrasonic transducer comprising:

a piezoelectric layer comprising:

an array of piezoelectric posts configured for emitting and receiving ultrasonic wave, the material of each of the piezoelectric posts comprising lead zirconate titanate piezoelectric ceramics;

a plurality of emitting electrodes formed on a lower surface of the piezoelectric layer by a sputtering process; and

a plurality of receiving electrodes formed on an upper surface of the piezoelectric layer by the sputtering process; wherein each of the emitting electrodes and each of the receiving electrodes comprise lead, zirconium, titanium, and/or alloys thereof;

wherein the piezoelectric posts are arranged in a matrix;

a plurality of emitting electrode lines formed on the lower surface of the piezoelectric layer, each of the emitting electrode lines is connected to a row of the piezoelectric posts; and

a plurality of receiving electrode lines formed on the upper surface of the piezoelectric layer, each of the receiving electrode lines is connected to a column of the piezoelectric posts.

2. The ultrasonic transducer of claim 1 , wherein the emitting electrodes and the receiving electrodes are made of titanium-silicon alloy, titanium-zinc alloy, or titanium-nickel alloy.

3. The ultrasonic transducer of claim 1 , wherein the ultrasonic transducer comprises:

a lower protective layer arranged on lower ends of the emitting electrodes; and

an upper protective layer arranged on the upper ends of the receiving electrodes.

4. The ultrasonic transducer of claim 1 , wherein the piezoelectric layer further comprises a filling portion, and the filling portion is filled with gaps between the piezoelectric posts.

5. The ultrasonic transducer of claim 1 , wherein the cross-section of each of the piezoelectric posts is substantially square.

6. The ultrasonic transducer of claim 1 , the height of each of the piezoelectric posts is about 70-80 micrometers.

7. The ultrasonic transducer of claim 4 , the filling portion is made of epoxy resin.

8. The ultrasonic transducer of claim 1 , wherein the array of piezoelectric posts are formed by cutting groove grids on the piezoelectric material from a first direction and a second direction in a predetermined depth, and the first direction is perpendicular to the second direction.

9. The ultrasonic transducer of claim 1 , wherein the array of piezoelectric posts are formed by etching a filling material at a predetermined position to form a plurality of columnar through holes, and then filling piezoelectric material in the columnar through holes.

10. A method for manufacturing an ultrasonic transducer, comprising:

forming a piezoelectric layer, the piezoelectric layer comprising a plurality of piezoelectric posts, the material of each of the piezoelectric posts comprising lead zirconate titanate piezoelectric ceramics; and

sputtering emitting electrodes on a lower surface of the piezoelectric layer and sputtering receiving electrodes on an upper surface of the piezoelectric layer, and each of the emitting electrodes and each of the receiving electrodes comprise lead, zirconium, titanium, and/or alloys thereof;

wherein the step of forming a piezoelectric layer comprises:

etching a filling material at a predetermined position to form a plurality of columnar through holes; and

filling piezoelectric material in the columnar through holes.

11. The method of claim 10 , wherein the step of sputtering process comprises:

impinging a target with predetermined ions so that the component on a surface of the target is sputtered out of the target in the form of atoms or ions; and

depositing the atoms or the ions on the lower surface and the upper surface of the piezoelectric layer to form the emitting electrodes and the receiving electrodes.

12. The method of claim 11 , wherein the target comprises a lead target, a zirconium target, or a titanium target.

13. The method of claim 12 , wherein the target comprises a titanium silicon target, a titanium zinc target, or a titanium nickel target.

14. The method of claim 12 , wherein the method further comprises:

forming a lower protective layer on lower ends of the emitting electrodes; and

forming an upper protective layer on upper ends of the receiving electrodes.

15. An ultrasonic fingerprint recognition sensor, comprising:

a substrate;

a control chip positioned on and electrically connected to the substrate;

an ultrasonic transducer positioned on and electrically connected to the control chip, the ultrasonic transducer comprising:

a piezoelectric layer comprising:

an array of piezoelectric posts configured for emitting and receiving ultrasonic wave, the material of each of the piezoelectric posts comprising lead zirconate titanate piezoelectric ceramics;

a plurality of emitting electrodes formed on a lower surface of the piezoelectric layer by a sputtering process; and

a plurality of receiving electrodes formed on an upper surface of the piezoelectric layer by the sputtering process; wherein each of the emitting electrodes and each of the receiving electrodes comprise lead, zirconium, titanium, and/or alloys thereof;

wherein the piezoelectric posts are arranged in a matrix;

a plurality of emitting electrode lines formed on the lower surface of the piezoelectric layer, each of the emitting electrode lines is connected to a row of the piezoelectric posts; and

a plurality of receiving electrode lines formed on the upper surface of the piezoelectric layer, each of the receiving electrode lines is connected to a column of the piezoelectric posts; and

a package packing the substrate, the control chip, and the ultrasonic transducer as a module.

16. An electronic device comprising:

a casing; and

an ultrasonic fingerprint recognition sensor positioned in the casing for fingerprint recognition or authorization, the ultrasonic fingerprint recognition sensor, comprising:

a substrate;

a control chip positioned on and electrically connected to the substrate;

an ultrasonic transducer positioned on and electrically connected to the control chip, the ultrasonic transducer comprising:

a piezoelectric layer comprising:

an array of piezoelectric posts configured for emitting and receiving ultrasonic wave, the material of each of the piezoelectric posts comprising lead zirconate titanate piezoelectric ceramics;

a plurality of emitting electrodes formed on a lower surface of the piezoelectric layer by a sputtering process; and

a plurality of receiving electrodes formed on an upper surface of the piezoelectric layer by the sputtering process; wherein each of the emitting electrodes and each of the receiving electrodes comprise lead, zirconium, titanium, and/or alloys thereof;

wherein the piezoelectric posts are arranged in a matrix;

a plurality of emitting electrode lines formed on the lower surface of the piezoelectric layer, each of the emitting electrode lines is connected to a row of the piezoelectric posts; and

a plurality of receiving electrode lines formed on the upper surface of the piezoelectric layer, each of the receiving electrode lines is connected to a column of the piezoelectric posts; and

a package packing the substrate, the control chip, and the ultrasonic transducer as a module.