CAPACITIVE ULTRASONIC TRANSDUCER AND METHOD OF FABRICATING THE SAME

Abstract

A capacitive ultrasonic transducer includes a first electrode, an insulating layer formed on the first electrode, at least one support frame formed on the insulating layer, and a second electrode formed spaced apart from the first electrode, wherein the first electrode and the second electrode define an effective area of oscillation of the capacitive ultrasonic transducer, and the respective length of the first electrode and the second electrode defining the effective area of oscillation is substantially the same.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The foregoing summary, as well as the following detailed description of the invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there are shown in the drawings examples which are presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown.

In the drawings:

FIG. 1 is a schematic cross-sectional view of a conventional capacitive ultrasonic transducer;

FIGS. 2A to 2D are cross-sectional diagrams illustrating a conventional method for fabricating a capacitive ultrasonic transducer;

FIG. 3A is a schematic cross-sectional view of a capacitive ultrasonic transducer in accordance with one example of the present invention;

FIG. 3B is a schematic cross-sectional view of a capacitive ultrasonic transducer in accordance with another example of the present invention;

FIGS. 4A to 4G are schematic cross-sectional diagrams illustrating a method for fabricating capacitive ultrasonic transducers in accordance with one example of the invention;

FIGS. 4D-1 and 4E-1 are schematic cross-sectional diagrams illustrating a method for fabricating capacitive ultrasonic transducers in accordance with one example of the invention;

FIGS. 5A to 5G are schematic cross-sectional diagrams illustrating a method for fabricating capacitive ultrasonic transducers in accordance with another example of the invention;

FIGS. 5D-1 and 5E-1 are schematic cross-sectional diagrams illustrating a method for fabricating capacitive ultrasonic transducers in accordance with one example of the invention;

FIGS. 6A to 6D are schematic cross-sectional diagrams illustrating a method for fabricating capacitive ultrasonic transducers in accordance with yet another example of the present invention;

FIG. 7 is a schematic cross-sectional view of a capacitive ultrasonic transducer in accordance with another example of the present invention;

FIG. 8A is a schematic cross-sectional diagram illustrating a method for fabricating capacitive ultrasonic transducers in accordance with one example of the present invention; and

FIG. 8B is a schematic cross-sectional diagram illustrating a method for fabricating capacitive ultrasonic transducers in accordance with another example of the present invention.

Claims

1. A capacitive ultrasonic transducer, comprising: a conductive substrate;an insulating layer formed on the conductive substrate;a support frame formed on the insulating layer; anda conductive layer spaced apart from the conductive substrate by the support frame having substantially the same thermal coefficient as the support frame.

2. The capacitive ultrasonic transducer of claim 1, wherein the support frame includes a material selected from one of nickel (Ni), nickel-cobalt (NiCo), nickel-ferrite (NiFe) and nickel-manganese (NiMn).

3. The capacitive ultrasonic transducer of claim 1, wherein the conductive layer includes a material selected from one of nickel (Ni), nickel-cobalt (NiCo), nickel-ferrite (NiFe) and nickel-manganese (NiMn).

4. The capacitive ultrasonic transducer of claim 1, further comprising at least one bump disposed above the support frame.

5. The capacitive ultrasonic transducer of claim 4, wherein the at least one bump includes a material selected from one of Ni, NiCo, NiFe and NiMn.

6. The capacitive ultrasonic transducer of claim 1, wherein the support frame includes a seed layer formed on the insulating layer.

7. The capacitive ultrasonic transducer of claim 6, wherein the seed layer includes a material selected from one of titanium (Ti), copper (Cu), Ni, NiCo, NiFe and NiMn.

8. The capacitive ultrasonic transducer of claim 1, wherein the support frame and the conductive layer includes substantially the same material.

9. A capacitive ultrasonic transducer, comprising: a first electrode;an insulating layer formed on the first electrode;at least one support frame formed on the insulating layer; anda second electrode formed spaced apart from the first electrode, wherein the first electrode and the second electrode define an effective area of oscillation of the capacitive ultrasonic transducer, and the respective length of the first electrode and the second electrode defining the effective area of oscillation is substantially the same.

10. The capacitive ultrasonic transducer of claim 9, wherein the support frame and the second electrode is formed of substantially the same material.

11. The capacitive ultrasonic transducer of claim 9, further comprising at least one bump disposed above the at least one support frame.

12. The capacitive ultrasonic transducer of claim 9, wherein the at least one support frame includes a seed layer formed on the insulating layer.

13. A capacitive ultrasonic transducer, comprising: a substrate;a support frame formed over the substrate; anda conductive layer held by the support frame over the substrate so that a chamber is defined by the conductive layer, the support frame and the substrate.

14. The capacitive ultrasonic transducer of claim 13, further comprising a patterned insulating layer formed between the support frame and the substrate.

15. The capacitive ultrasonic transducer of claim 14, wherein the support frame includes a seed layer formed on the patterned insulating layer.

16. The capacitive ultrasonic transducer of claim 13, wherein the respective length of the conductive layer and the substrate defining the chamber is substantially the same.

17. The capacitive ultrasonic transducer of claim 13, wherein the support frame and the conductive layer include substantially the same material.

18. A method for fabricating capacitive ultrasonic transducers, comprising: providing a substrate;forming an insulating layer on the substrate;forming a patterned first metal layer on the insulating layer;forming a patterned second metal layer substantially coplanar with the patterned first metal layer;forming a patterned third metal layer on the patterned first metal layer and the patterned second metal layer, exposing portions of the patterned first metal layer through openings; andremoving the patterned first metal layer through the openings.

19. The method of claim 18, further comprising: forming a patterned photoresist layer over the insulating layer; andforming a patterned first metal layer substantially coplanar with the patterned photoresist layer.

20. The method of claim 18, further comprising: removing the patterned first metal layer through the openings, exposing portions of the insulating layer; andremoving the portions of the insulating layer.

21. The method of claim 18, further comprising: forming a metal layer on the patterned first metal layer and the patterned second metal layer;forming a patterned fourth metal layer in the metal layer in location corresponding to the patterned second metal layer; andpatterning and etching the metal layer to form the patterned third metal layer.

22. The method of claim 18, further comprising forming a patterned metal layer to fill the openings.

23. The method of claim 18, further comprising: forming a fourth metal layer on the insulating layer; andforming the patterned photoresist layer on the fourth metal layer.

24. The method of claim 18, further comprising forming the patterned second metal layer and the patterned third metal layer with substantially the same material.

25. The method of claim 18, further comprising forming the patterned second metal layer, the patterned third metal layer and the fourth metal layer with substantially the same material.

26. A method for fabricating capacitive ultrasonic transducers, comprising: providing a substrate;forming an insulating layer on the substrate;forming a patterned first metal layer on the insulating layer;forming a second metal layer on the patterned first metal layer;patterning the second metal layer to expose portions of the patterned first metal layer through openings; andremoving the patterned first metal layer through the openings.

27. The method of claim 26, further comprising: forming a patterned photoresist layer over the insulating layer; andforming a patterned first metal layer substantially coplanar with the patterned photoresist layer.

28. The method of claim 26, further comprising: removing the patterned first metal layer through the openings, exposing portions of the insulating layer; andremoving the portions of the insulating layer.

29. The method of claim 26, further comprising: forming a third metal layer on the second metal layer; andpatterning the third metal layer to form bumps on the second metal layer.

30. The method of claim 26, further comprising forming a patterned metal layer to fill the openings.

31. The method of claim 26, further comprising: forming a fourth metal layer on the insulating layer; andforming the patterned photoresist layer on the fourth metal layer.

32. The method of claim 29, further comprising forming the second metal layer and the third metal layer with substantially the same material.

33. The method of claim 31, further comprising forming the second metal layer and the fourth metal layer with substantially the same material.

34. A method for fabricating capacitive ultrasonic transducers, comprising: providing a substrate;forming an insulating layer on the substrate;forming a metal layer on the insulating layer;forming a patterned photoresist layer on the metal layer, exposing portions of the metal layer;forming a patterned first metal layer substantially coplanar with the patterned photoresist layer;removing the patterned photoresist layer;forming a patterned second metal layer substantially coplanar with the patterned first metal layer;forming a patterned third metal layer on the patterned first metal layer and the patterned second metal layer, exposing portions of the patterned first metal layer through openings; andremoving the patterned first metal layer and portions of the metal layer through the openings.

35. The method of claim 34, further comprising: forming a metal layer on the patterned first metal layer and the patterned second metal layer;forming a patterned fourth metal layer in the metal layer in location corresponding to the patterned second metal layer; andpatterning and etching the metal layer to form the patterned third metal layer.

36. The method of claim 34, further comprising forming a patterned metal layer to fill the openings.

37. The method of claim 34, further comprising forming the patterned second metal layer and the patterned third metal layer with substantially the same material.

38. The method of claim 35, further comprising forming the metal layer, the patterned second metal layer and the patterned third metal layer with substantially the same material.

39. The method of claim 34, further comprising forming a metal layer on the insulating layer with a material selected from one of Ti, Cu, Ni, NiCo, NiFe and NiMn.

40. The method of claim 34, further comprising: removing the patterned first metal layer and portions of the metal layer through the openings, exposing portions of the insulating layer; andremoving the portions of the insulating layer.