PRESSURE SENSOR, ESPECIALLY PRESSURE DIFFERENCE SENSOR

• US 20120279310A1
• Filed: 10/07/2010
• Published: 11/08/2012
• Est. Priority Date: 10/30/2009
• Status: Abandoned Application

• Current Assignee: Endress+Hauser SE+Co. KG (Endress+Hauser AG)
• Original Assignee: Endress + Hauser GmbH + Company KG (Endress+Hauser AG)
• Inventors: Philipps, Michael, Stolze, Dieter, Tham, Anh Tuan, Werthschutzky, Roland, Kober, Timo
• Application Number:
  US13/503,804
• Publication Number:
  US 20120279310A1
• Time in Patent Office: Days
• US Class Current: 73/717
• CPC Class Codes: C03B 23/0026 by gravity, e.g. sagging C03B23/02, C03B23/04, C03B23/18 take precedence
• CPC Class Codes: G01L 19/0618 Overload protection
• CPC Class Codes: G01L 9/0042 Constructional details associated with semiconductive diaphragm sensors, e.g. etching, or constructional details of non-semiconductive diaphragms details about the integration or bonding of piezoresistor in or on the diaphragm G01L9/0052 and G01L9/0057 respectively

Abstract

The pressure sensor of the invention includes at least one platform, at least one measuring membrane 30, and a transducer, wherein the measuring membrane comprises a semiconductor material, wherein the measuring membrane, enclosing a pressure chamber, is secured on the platform, wherein the measuring membrane is contactable with at least one pressure and is elastically deformable in a pressure-dependent manner, wherein the transducer provides an electrical signal dependent on deformation of the measuring membrane, wherein the platform has a membrane bed, on which the measuring membrane lies in the case of overload, in order to support the measuring membrane, wherein the membrane bed 21 has a glass layer 20, whose surface faces the measuring membrane and forms a wall of the pressure chamber, wherein the surface of the glass layer has a contour, which is suitable for supporting the measuring membrane 30 in the case of overload, characterized in that the contour of the membrane bed 21 is obtainable by a sagging of an unsupported region of a glass plate at increased temperature, due to the force of gravity on the unsupported region of the glass plate, and subsequent cooling of the glass plate.

Claims

1-12. -12. (canceled)

13. A pressure sensor, comprising:

at least one platform;

at least one measuring membrane; and

a transducer, wherein;

said at least one measuring membrane comprises a semiconductor material, encloses a pressure chamber, is secured on said at least one platform, is contactable with at least one pressure, and is elastically deformable in a pressure-dependent manner;

said transducer provides an electrical signal dependent on deformation of said at least one measuring membrane;

said at least one platform has a membrane bed, on which said at least one measuring membrane lies in the case of overload, in order to support said at least one measuring membrane;

said membrane bed has a glass layer, whose surface faces said at least one measuring membrane and forms a wall of said pressure chamber;

said surface of said glass layer has a contour, which is suitable for supporting said at least one measuring membrane in the case of overload; and

said contour of said membrane bed is obtainable by a sagging of an unsupported region of a glass plate at increased temperature, due to the force of gravity on the unsupported region of said glass plate, and subsequent cooling of said glass plate.

14. The pressure sensor as claimed in claim 13, wherein:

said at least one platform comprises a substrate, which has a surface facing said glass layer, which supports said glass layer; and

said surface has a cavity, via which the contour of said membrane bed is formed.

15. The pressure sensor as claimed in claim 13, wherein:

said cavities are filled on the rear side with a fill material, in order to prevent hollow spaces under said glass layer.

16. The pressure sensor as claimed in claim 15, wherein:

the fill material especially comprises a glass, which has a lower melting temperature than the glass of said glass layer.

17. The pressure sensor as claimed in claim 13, wherein:

said glass layer has a thickness of not less than 100 μ

m, preferably not less than 200 μ

m and further preferably not less than 400 μ

m.

18. The pressure sensor as claimed in claim 13, wherein:

said glass layer has a thickness of no more than 2000 μ

m, preferably no more than 1400 μ

m and further preferably no more than 1000 μ

m.

19. The pressure sensor as claimed in claim 13, wherein:

said membrane bed has an aspherical surface contour, especially approximately the deflection curve of said at least one measuring membrane, or equal thereto.

20. A method for the preparation of a membrane bed of a pressure sensor, comprising the steps of:

(a) providing a planar glass layer;

(b) applying the glass layer on a support body, which has a surface, which supports the glass layer, wherein the surface has at least one cavity, so that the glass layer is not supported in the region of the cavity;

(c) heating the glass layer to a temperature or temperature range, at which the unsupported region of the glass layer sinks; and

(d) allowing the glass layer to cool.

21. The method as claimed in claim 20, wherein:

the glass layer, after reaching a temperature, at which the unsupported region sinks, is held for a holding time at such temperature, so that the glass layer can sink to a sufficient extent.

22. The method as claimed in claim 21, wherein:

the holding time for a borosilicate glass is given by the relationship t=a*d+b;

the value for a at 750°

C. lies between 0.1 and 0.8, especially between 0.2 and 0.6, and the value for b lies between −

60 and 20, especially between −

40 and 0, wherein t is the time in minutes and d the thickness of the glass layer in μ

m.

23. The method as claimed in claim 20, wherein:

the preparation of the membrane bed contour occurs on one undivided wafer for a plurality of membrane beds.

24. A method for manufacturing a pressure sensor, comprising:

preparing a membrane bed according to the method as claimed in claim 20, and joining a measuring membrane with the platform, or the glass layer of the platform, which forms the membrane bed.