Anticorrosive vacuum sensor

Abstract

The present invention concerns the capacitive vacuum sensor that includes an elastic diaphragm electrode and rigid fixed electrodes disposed to face opposite the elastic diaphragm electrode, with an internal space being delimited between the elastic diaphragm electrode and rigid fixed electrodes, wherein the elastic diaphragm electrode deflects elastically in response to any change in the pressure of a gas applied on the said elastic diaphragm electrode, and wherein the capacitive vacuum sensor is responsive to any change in the capacitance between the elastic diaphragm electrode and rigid fixed electrodes that may occur in accordance with the deflection of the elastic diaphragm electrode so that it can measure the pressure of the gas. In the present invention, the capacitive vacuum sensor is provided as the anticorrosion vacuum sensor that includes an anticorrosive diaphragm electrode that can resist the corrosive action of the reactive gas when it is exposed to such gas, and is fabricated by the micromachining technology. Thereby, the capacitive vacuum sensor that has the resistance to the reactive gases as well as the high quality, and can be manufactured on the massive production basis is provided.

What is claimed is:  
     
         1 . An anticorrosive vacuum sensor of the class of the capacitive vacuum sensor manufactured by the micromachining technique, including: 
 an elastic diaphragm electrode elastically deflects in response to any change in the pressure of a gas applied on the said elastic diaphragm electrode; and    rigid fixed electrodes disposed to face opposite said elastic diaphragm electrode, said elastic diaphragm electrode and said rigid fixed electrodes defining a closed space therebetween, and said capacitive vacuum sensor being responsive to any change in the capacitance between said elastic diaphragm electrode and said rigid fixed electrodes that occurs in response to the deflection of said elastic diaphragm electrode, for measuring said pressure of the gas, wherein    said elastic diaphragm electrode is formed to be anticorrosive.    
     
     
         2 . The anticorrosive vacuum sensor as defined in  claim 1 , wherein said elastic diaphragm electrode is formed like a thin film diaphragm that is slightly stressed to provide the tensile stress.  
     
     
         3 . The anticorrosive vacuum sensor as defined in  claim 1 , wherein said elastic diaphragm electrode contains doped impurities that enhance the conductivity of said elastic diaphragm electrode.  
     
     
         4 . The anticorrosive vacuum sensor as defined in  claim 2 , wherein said elastic diaphragm electrode contains doped impurities that enhance the conductivity of said elastic diaphragm electrode.  
     
     
         5 . The anticorrosive vacuum sensor as defined in  claim 1 , further including an electrically conductive thin film deposited on the side of said elastic diaphragm electrode facing said rigid fixed electrodes.  
     
     
         6 . The anticorrosive vacuum sensor as defined in  claim 2 , further including an electrically conductive thin film deposited on the side of said elastic diaphragm electrode facing said rigid fixed electrodes.  
     
     
         7 . The anticorrosive vacuum sensor as defined in  claim 1 , wherein said elastic diaphragm electrode is formed from any one of silicon carbide, alumina and aluminum nitride.  
     
     
         8 . The anticorrosive vacuum sensor as defined in  claim 2 , wherein said elastic diaphragm electrode is formed from any one of silicon carbide, alumina and aluminum nitride.  
     
     
         9 . The anticorrosive vacuum sensor as defined in  claim 3 , wherein said elastic diaphragm electrode is formed from any one of silicon carbide, alumina and aluminum nitride.  
     
     
         10 . The anticorrosive vacuum sensor as defined in  claim 4 , wherein said elastic diaphragm electrode is formed from any one of silicon carbide, alumina and aluminum nitride.  
     
     
         11 . The anticorrosive vacuum sensor as defined in  claim 5 , wherein said elastic diaphragm electrode is formed from any one of silicon carbide, alumina and aluminum nitride.  
     
     
         12 . The anticorrosive vacuum sensor as defined in  claim 6 , wherein said elastic diaphragm electrode is formed from any one of silicon carbide, alumina and aluminum nitride.