Pressure Sensor Having Sealed And Apertured Chambers

Abstract

A pressure sensor is provided having a substrate assembly having a first substrate bonded to a second substrate via an intermediate bonding layer so as to define sealed channels in the first substrate, a sealed reference chamber on said first substrate and having the sealed channels, and an apertured chamber on said first substrate and covering the sealed reference chamber.

1 . A pressure sensor comprising:
 a substrate assembly having a first substrate bonded to a second substrate via an intermediate bonding layer so as to define sealed channels in the first substrate;   a sealed reference chamber on said first substrate and having said sealed channels; and   an apertured chamber on said first substrate and covering the sealed reference chamber.   
   
   
       2 . A pressure sensor as claimed in  claim 1 , wherein the sealed reference chamber is defined by a conductive layer on the first substrate and a conductive membrane extending from the first substrate which is spaced from the conductive layer. 
   
   
       3 . A pressure sensor as claimed in  claim 2 , wherein the apertured chamber is defined by a cap having apertures which extends from the first substrate to cover the conductive membrane. 
   
   
       4 . A pressure sensor as claimed in  claim 2 , wherein:
 the first substrate is a silicon substrate;   a CMOS layer is deposited on the silicon substrate;   the conductive layer is deposited on the CMOS layer; and   a protective passivation layer is deposited on the conductive layer.   
   
   
       5 . A pressure sensor as claimed in  claim 4 , wherein the passivation layer is formed from an insulating material. 
   
   
       6 . A pressure sensor as claimed in  claim 4 , wherein the passivation layer is formed from a semi-conducting material. 
   
   
       7 . A pressure sensor as claimed in  claim 4 , wherein the CMOS layer has guard rings surrounding the sealed channels to prevent air contained in the sealed channels from corroding circuitry. 
   
   
       8 . A pressure sensor as claimed in  claim 3 , wherein the membrane has a peripheral portion which is located between the substrate assembly and the cap. 
   
   
       9 . A pressure sensor as claimed in  claim 8 , wherein the cap has a peripheral portion on the peripheral portion of the membrane. 
   
   
       10 . A pressure sensor as claimed in  claim 1 , wherein the intermediate bonding layer comprises a low melting point material. 
   
   
       11 . A pressure sensor as claimed in  claim 11 , wherein the low melting point material is selected from the group consisting of: Au—Si; Glass Frit; Au—Au; PDMS; TiN; Si 3 N 4 ; LPCVD PSG; APCVD BO; and Boron-Doped Si.