Membrane bonding with photoresist

Patent metadata

Field	Value
Publication number	US-10065854-B2
Application number	US-201615154900-A
Country	US
Kind code	B2
Filing date	May 13, 2016
Priority date	May 20, 2015
Publication date	Sep 4, 2018
Grant date	Sep 4, 2018

Abstract

Systems and techniques are provided for membrane bonding. A photoresist may be applied to an ultrasonic device. A portion of the photoresist may be removed. A bonding agent may be applied a portion of the photoresist that is not removed. A membrane may be placed on the ultrasonic device such that the membrane is in contact with the ultrasonic device through the bonding agent and the photoresist. The membrane and the ultrasonic device may be placed in between a first flat plate and a second flat plate, such that the second flat plate rests on top of the membrane. Light pressure may be applied to the membrane. The light pressure may be applied by one or more of the weight of the second flat plate and a pressure providing device applying pressure to either or both of the first flat plate and the second flat plate.

First claim

The invention claimed is:

1. A method comprising:
applying a photoresist to an ultrasonic device;
covering a first portion of the photoresist on the ultrasonic device;
exposing a second portion of the photoresist that was not covered to a light source;
removing either the first portion of the photoresist or the second portion of the photoresist to create a remaining portion of the photoresist on the ultrasonic device;
applying a bonding agent to the remaining portion of the photoresist on the ultrasonic device;
placing a membrane on the ultrasonic device such that the membrane is in contact with the ultrasonic device through the bonding agent;
placing the membrane and the ultrasonic device in between a first flat plate and a second flat plate, such that the second flat plate rests on top of the membrane; and
applying light pressure to the membrane, wherein the light pressure is applied by one or more of the weight of the second flat plate and a pressure providing device applying pressure to either or both of the first flat plate and the second flat plate.

2. The method of claim 1 , wherein applying the bonding agent to the ultrasonic device comprises:
applying the bonding agent to a roller; and
rolling the roller across a top of the remaining portion of the photoresist on the ultrasonic device.

3. The method of claim 2 , wherein the top of the remaining portion of the photoresist on the ultrasonic device protrudes from the surface of the ultrasonic device by between 15 microns and 20 microns.

4. The method of claim 1 , wherein the remaining portion of the photoresist on the ultrasonic device forms transducer cell boundaries for at least one transducer cell.

5. The method of claim 2 , wherein the bonding agent applied to the ultrasonic device creates borders of ultrasonic transducer cells, and wherein a dot of the bonding agent is applied to the tips of the free ends of electromechanically active devices of the ultrasonic device.

6. The method of claim 1 , wherein the second portion of the photoresist is removed when the photoresist is a positive photoresist and wherein the first portion of the photoresist is removed when the photoresist is a negative photoresist.

7. The method of claim 1 , wherein the bonding agent is an epoxy.

8. The method of claim 1 , wherein the light pressure is applied for the entire curing time of the bonding agent.

9. The method of claim 1 , wherein the bonding agent cures to form bond lines bonding the membrane to the ultrasonic device.

10. The method of claim 9 , wherein the bond lines divide the membrane into mechanically isolated membrane sections.

11. The method of claim 10 , wherein each of the membrane sections is bonded by the cured bonding agent to the tip of the free end of an electromechanically active device covered by the membrane section.

12. The method of claim 11 , wherein the electromechanically active device is bonded to the membrane section off the center of the membrane section.

13. The method of claim 11 , wherein the electromechanically active device is a piezoelectric unimorph or a piezoelectric bimorph.

14. The method of claim 1 , further comprising keeping the membrane and ultrasonic device at a temperature below 90 degrees Celsius for the curing time of the bonding agent.

15. The method of claim 1 , further comprising, before placing the membrane on the ultrasonic device, preparing or texturing at least one surface of the membrane.

16. The method of claim 1 , wherein the membrane comprises a metal or metal-patterned film.

17. The method of claim 1 , wherein the ultrasonic device comprises a laminate material that comprises one or more flexures.

18. The method of claim 1 , wherein the ultrasonic device comprises one or more ultrasonic transducers on a substrate.

19. The method of claim 18 , wherein each ultrasonic transducer comprises an electromechanically active device attached to the substrate and partially projecting out over a cavity in the substrate.

20. The method of claim 1 , further comprising:
before placing the membrane on the ultrasonic device, applying a second photoresist to the membrane;
covering a first portion of the second photoresist on the membrane;
exposing a second portion of the second photoresist that was not covered to a light source;
removing either the first portion of the second photoresist or the second portion of the second photoresist to create a remaining portion of the photoresist on the membrane; and
applying the bonding agent to the remaining portion of the second photoresist on the membrane.

21. A method comprising:
applying a photoresist to an ultrasonic device;
covering a first portion of the photoresist on the ultrasonic device;
exposing a second portion of the photoresist that was not covered to a light source, wherein the second portion of the photoresist forms transducer cell boundaries between ultrasonic transducers of the ultrasonic device and forms photoresist dots on the tips of electromechanically active devices of the ultrasonic device;
removing the first portion of the photoresist to create a remaining portion of the photoresist on the ultrasonic device, the remaining portion of the photoresist comprising the second portion of the photoresist;
applying an epoxy to the remaining portion of the photoresist on the ultrasonic device, wherein the epoxy forms epoxy lines on the ultrasonic device, and wherein is epoxy is applied to photoresist on the electromechanically active devices of the ultrasonic transducers;
placing a membrane on the ultrasonic device such that the membrane is in contact with the epoxy, wherein the membrane covers one or more of the ultrasonic transducers;
placing the membrane and the ultrasonic device between a first flat plate and a second flat plate, such that the second flat plate is in contact with the membrane and the first flat plate is in contact with the ultrasonic device opposite the second flat plate; and
applying light pressure to the membrane or the ultrasonic device through either or both of the first flat plate and the second flat plate for at least part of the curing time of the epoxy.

22. The method of claim 21 , wherein the epoxy lines are based the transducer cell boundaries formed by the second portion of the photoresist.

23. The method of claim 21 , wherein the epoxy lines form bond lines after the epoxy has cured.

24. The method of claim 23 , wherein the bond lines divide the ultrasonic device into one or more ultrasonic transducer cells, wherein each ultrasonic transducer cell comprises one or more ultrasonic transducers.

25. The method of claim 24 , wherein each of the ultrasonic transducer cells further comprises a membrane section of the membrane bonded to the borders of the ultrasonic transducer cell by the cured epoxy of the bond lines.

26. The method of claim 25 , wherein each membrane section is mechanically isolated from the other membrane sections of the membrane by the bond lines.

27. The method of claim 26 , wherein an electromechanically active device of one of the ultrasonic transducers moves the membrane section covering the ultrasonic transducer without disturbing a neighboring membrane section.

28. The method of claim 25 , wherein the electromechanically active device is bonded to a membrane section of the membrane off the center of the membrane section.

29.

Assignees

• Ubeam Inc

Inventors

• Joyce Andrew
• Taffler Sean
• Reynolds Paul
• Nemeth Nicholas Lavada
• Elhadad Adam Stephen
• Faraji Boozarjomehr

Classifications

• H10P95/00

  Generic processes or apparatus for manufacture or treatments not covered by the other groups of this subclass · CPC title

• B81B2203/0127

  Diaphragms, i.e. structures separating two media that can control the passage from one medium to another; Membranes, i.e. diaphragms with filtering function · CPC title

• G03F7/00

  Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor (using photoresist structures for special production processes, see the relevant places, e.g. B44C, H10P76/00, H05K) · CPC title

• B81C1/00182 Primary

  Arrangements of deformable or non-deformable structures, e.g. membrane and cavity for use in a transducer · CPC title

• B81B2201/0271

  Resonators; ultrasonic resonators · CPC title