Integratable transducer structure

• US 6,552,404 B1
• Filed: 04/17/2001
• Issued: 04/22/2003
• Est. Priority Date: 04/17/2001
• Status: Expired due to Term

• Current Assignee: Analog Devices, Inc.
• Original Assignee: Analog Devices, Inc.
• Inventors: Hynes, Eamon, Wynne, John
• Primary Examiner(s): Nelms, David
• Assistant Examiner(s): Huynh, Andy
• Application Number:
  US09/836,809
• Time in Patent Office: 735 Days
• Field of Search: 257/414-420, 257/421, 438/50-53
• US Class Current: 257/415
• CPC Class Codes: G01L 9/0019 of a semiconductive element
• CPC Class Codes: G01L 9/0073 using a semiconductive diaphragm

Abstract

Electro-mechanical structures and methods for forming same are disclosed. The structures are integratable onto an integrated circuit. The structures have a deformeable element formed in a plane substantially perpendicular to the substrate of the integrated circuit.

Claims

1. An integrated circuit comprising:

a substrate having an upper surface defining a first plane;

an electromechanical element including a deformable element defining a second plane which intersects the first plane and wherein the deformable element is deformable in a direction perpendicular to the second plane.

2. The integrated circuit of claim 1, wherein the first and second planes are substantially perpendicular with respect to one another.

3. The integrated circuit of claim 2, wherein the electromechanical element is insulated from the upper surface of the substrate.

4. The integrated circuit of claim 1, wherein the electromechanical element is a transducer element responsive to applied pressure, said applied pressure effecting a change in the electrical characteristics of said transducer.

5. The integrated circuit of claim 4 wherein the deformable element is a transducer diaphragm forming a first wall of an evacuated cavity, an outer portion of the first wall being exposed to ambient pressure conditions and an inner portion of the first wall being exposed to an evacuated cavity, such that changes in ambient pressure with respect to the evacuated cavity effect a deflection of the diaphragm, such deflection being electrically measurable.

6. The integrated circuit of claim 1 wherein the deformable element forms a first wall of an evacuated cavity, the cavity having a second wall, the second wall of the cavity being electrically insulated from the first wall, such that on application of a signal between the first wall and the second wall the deformable element is actuated, the actuation of the deformable element resulting in the deformable element vibrating mechanically.

7. The integrated circuit of claim 6 wherein the frequency of the deformable element vibration is modulated by the frequency of the signal applied to the first wall and second wall.

8. An integrated circuit comprising:

a substrate having an upper surface,

an electromechanical element formed on the upper surface, the electromechanical element being elongated in a direction substantially perpendicular to the substrate upper surface.

9. The integrated circuit of claim 8, wherein the electromechanical element is insulated from the upper surface of the substrate.

10. The integrated circuit of claim 8, wherein the electromechanical element forms a transducer being responsive to applied pressure, said applied pressure effecting a change in the electrical characteristics of said transducer.

11. The integrated circuit of claim 10, wherein said change in electrical characteristics of said transducer is independent of the electrical characteristics of the remaining portion of the integrated circuit.

12. The integrated circuit of claim 8, wherein the electromechanical element comprises a deformable element formed in a plane substantially perpendicular to the substrate.

13. The integrated circuit of claim 12, wherein the electromechanical element further comprises at least one evacuated cavity.

14. The integrated circuit of claim 13, having one evacuated cavity, the deformable element forming a first wall of said evacuated cavity, and wherein an outer portion of the deformable element is exposed to ambient pressure, and an inner portion of the deformable element is exposed to the evacuated cavity such that changes in ambient pressure with respect to the evacuated cavity effects a deflection of the diaphragm in the vertical plane, such deflection being electrically measurable.

15. The integrated circuit of claim 13, wherein the deformable element forms a first wall of the cavity and the cavity has a second wall electrically insulated from the first wall, such that the application of a signal between the first wall and the second wall actuates the deformable element.

16. The integrated circuit of claim 13 having two evacuated cavities, the deformable element forming a wall between the two evacuated cavities, the deformable element wall forming an inner wall of each cavity, each cavity also having an outer wall electrically insulated from the inner wall, such that an application of a signal between the inner wall and outer wall of either cavity actuates the deformable element.

17. The integrated circuit of claim 12 further comprising an evacuated cavity and wherein the deformable element is a column having a base and side walls formed within the cavity, the base of the column being proximal to the upper surface of the substrate of the integrated circuit, the column extending upwardly from the upper surface of the substrate, the side walls of the column being exposed to the cavity.

18. An integrated circuit having:

a substrate,

an electromechanical element formed on the substrate;

the electromechanical element having a deformable element formed in a substantially perpendicular plane with respect to the substrate and deformable in a direction substantially perpendicular to said plane, the electromechanical element further comprising at least one sealed cavity, at least a portion of the deformable element being exposed to the sealed cavity, and

wherein a deformation of the deformable element effects a change in the electrical characteristics of the electromechanical element.

19. A method of forming an electromechanical element having a deformable element and at least one evacuated cavity onto an integrated circuit substrate comprising the steps of:

a) masking at least a portion of an active device layer of the integrated circuit,

b) etching the device layer through the mask,

c) sealing at least a portion of the etched device layer so as to effect the formation of the at least one evacuated cavity within the active device layer, and

wherein the etching of the device layer through the mask effects the formation of at least one deformeable element, the element being deformable in a plane substantially perpendicular to the substrate of the integrated circuit.

20. The method according to claim 19 wherein the step of etching the device layer effects the formation of one deformable element, and the deformable element forms a wall of the at least one evacuated cavity.

21. The method according to claim 20 where in the steps of etching the device layer and sealing of the etched portion effects the formation of two cavities in the active device layer, the deformable element being formed as a shared wall between the two cavities.

22. The method according to claim 19 wherein the step of etching the device layer effects the formation of one deformable element within the at least one cavity.

23. The method according to claim 19 further comprising the step of electrically isolating the electromechanical element from the remaining integrated circuit.

24. A method of measuring pressure using an integrated transducer comprising the steps of:

a) forming at least one evacuated cavity in an active device layer of the integrated circuit,

b) isolating at least one wall of the at least one cavity from the active device layer of the integrated circuit so as to form a deformable element, the wall being formed in a plane substantially perpendicular to a substrate surface of the integrated circuit,

c) exposing at least one wall of the cavity to ambient pressure conditions so as to form a deformable membrane, and

d) sensing any deformation of the deformable element resultant in fluctuations in pressure between the ambient pressure and the evacuated cavity.

25. A method of forming an actuator on an integrated circuit comprising the steps of:

a) forming at least one evacuated cavity in an active device layer of the integrated circuit,

b) forming a deformable element in a plane substantially perpendicular to a substrate of the integrated circuit, at least a portion of the deformable element being exposed to the evacuated cavity, and

c) applying a signal between the deformable element and a wall of the evacuated cavity, said applied signal actuating the deformable element so as to generate a wave, the characteristics of the wave being defined by the applied signal.

26. The method according to claim 25 wherein the deformable element is formed by isolating at least one wall of the at least one cavity from the active device layer of the integrated circuit such that the deformable element forms a first wall of the cavity and the applied signal is applied between this first wall and a second wall of the cavity.