Pressure sensor and method for operating a pressure sensor

• US 7,040,173 B2
• Filed: 03/08/2005
• Issued: 05/09/2006
• Est. Priority Date: 03/08/2004
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Dehe, Alfons
• Primary Examiner(s): OEN, WILLIAM L
• Application Number:
  US11/075,034
• Publication Number:
  US 20050262947A1
• Time in Patent Office: 427 Days
• Field of Search: 737/06, 73715-728, 737/56, 361/283.1, 361/283.2, 361/283.3, 361/283.4, 600/558, 428/349
• US Class Current: 73/706
• CPC Class Codes: H04R 19/00 Electrostatic transducers

Abstract

A pressure sensor having a substrate, a counter-structure applied to the substrate, a dielectric on the counter-structure, a membrane on the dielectric, wherein the membrane or the counter-structure deflectable by a pressure applied, a protective structure, wherein the protective structure is isolated from the counter-structure or the membrane, wherein the protective structure is arranged with regard to the membrane or the counter-structure such that a capacity forms between the protective structure and the membrane or the protective structure and the counter-structure, and a provider for providing a potential at the protective structure differing from a potential at the counter-structure or the membrane.

Claims

1. A pressure sensor comprising:

a substrate;

a counter-structure applied to the substrate;

a dielectric on the counter-structure;

a membrane on the dielectric, wherein the membrane or the counter-structure is deflectable by a pressure applied;

a protective structure, the protective structure being isolated from the counter-structure and the membrane, the protective structure being arranged with regard to the membrane or the counter-structure such that a capacity forms between the protective structure and the membrane or the protective structure and the counter-structure; and

a provider for providing a potential at the protective structure differing from a potential at the counter-structure or the membrane.

2. The pressure sensor according to claim 1, which is formed as a capacitor microphone.

3. The pressure sensor according to claim 1, wherein the membrane or the counter-structure is in an area-overlapping relation to the protective structure.

4. The pressure sensor according to claim 1, wherein the substrate comprises an electrically conducting region.

5. The pressure sensor according to claim 1, wherein the electrically conducting region of the substrate forms a ground potential, wherein a potential of a protective structure, a potential of a membrane and a potential of a counter-structure are related to the ground potential.

6. The pressure sensor according to claim 1, wherein the substrate is electrically isolated from the counter-structure and the membrane.

7. The pressure sensor according to claim 1, wherein the membrane or the counter-structure includes an electrically conducting layer.

8. The pressure sensor according to claim 1, wherein the protective structure in a multi-layered setup is arranged in a same level as the membrane or the counter-structure.

9. The pressure sensor according to claim 8, wherein the recesses in the membrane or the counter-structure form lands and the protective structure overlaps the lands of the membrane or counter-structure not arranged in the same level.

10. The pressure sensor according to claim 8, wherein the protective structure of the membrane or counter-structure arranged in the same level of the multi-layered setup is electrically isolated from the membrane or the counter-structure by a recess.

11. The pressure sensor according to claim 8, wherein the multi-layered setup comprises a layer including the protective structure and the counter-structure or the protective structure and the membrane.

12. The pressure sensor according to claim 1, wherein the protective structure at least partially surrounds the membrane or the counter-structure.

13. The pressure sensor according to claim 1, wherein an electrical potential of a protective structure, in a state of rest, deviates less than 50% from the value of the potential of the counter-structure or the membrane.

14. The pressure sensor according to claim 1, wherein the provider for providing a potential of a protective structure determines a potential at the counter-structure or the membrane and sets a potential at the protective structure depending on the value of the potential.

15. The pressure sensor according to claim 14, wherein the provider for providing a potential at the protective structure sets the potential at the protective structure such that a potential value of the protective structure deviates less than 10% from the value of the potential at the membrane or the counter-structure.

16. The pressure sensor according to claim 15, wherein the protective structure and the membrane or the counter-structure are separated galvanically.

17. The pressure sensor according to claim 14, wherein the provider for providing a potential at the protective structure includes an impedance converter setting the potential on the protective structure via a voltage divider.

18. The pressure sensor according to claim 17, wherein the impedance converter includes a transistor with a potential depending on a potential of the membrane or the counter-structure applied to an input of the transistor and a potential depending on the potential of the protective structure applied to a second input.

19. The pressure sensor according to claim 1, wherein recesses in the membrane or the counter-structure form lands and an area of the protective structure overlaps the lands in the membrane or the counter-structure.

20. A method for operating a pressure sensor, comprising:

a substrate;

a counter-structure applied to the substrate;

a dielectric on the counter-structure;

a membrane on the dielectric, the membrane or the counter-structure being deflectable by a pressure applied; and

a protective structure arranged with regard to the membrane such that a capacity forms between the protective structure and the member or the protective structure and the counter-structure;

comprising a step of applying a potential to the protective structure differing from a potential of the counter-structure or the membrane.