Pressure sensor, especially pressure difference sensor

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.

1 - 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 μm, preferably not less than 200 μm and further preferably not less than 400 μm.   
     
     
         18 . The pressure sensor as claimed in  claim 13 , wherein:
 said glass layer has a thickness of no more than 2000 μm, preferably no more than 1400 μm and further preferably no more than 1000 μm.   
     
     
         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 μm.   
     
     
         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.