Semiconductor pressure sensor and pressure sensing device

Abstract

The object of the present invention is to propose an etch channel sealing structure characterized by excellent impermeability to moisture and resistance to temporal change of the diaphragm in the pressure sensor produced according to the sacrificial layer etching technique, and to provide a pressure sensor characterized by excellent productivity and durability. After a very small gap is formed by the sacrificial layer etching technique, silicon oxide film is deposited by the CVD technique or the like, there by sealing the etch channel. Further, impermeable thin film of polysilicon or the like is formed to cover the oxide film. This allows an etch channel sealing structure to be simplified in the pressure sensor produced according to the sacrificial layer etching technique, and prevents entry of moisture into the cavity, thereby improving moisture resistance. Moreover, sealing material with small film stress reduces temporal deformation of the diaphragm.

1 . A semiconductor pressure sensor comprising; 
 a substrate,    a diaphragm formed on said substrate by sacrificial layer etching method, and    a silicon oxide film provided by sealing the etchant filling hole of the sacrificial layer on the said diaphragm;    said semiconductor pressure sensor characterized in that a polysilicon film is provided to cover part or whole of said silicon oxide film.    
   
   
       2 . A semiconductor pressure sensor according to  claim 1  characterized in that the distance of said covered part is at least 10 microns or less from said etchant filling hole.  
   
   
       3 . A semiconductor pressure sensor according to  claim 1  characterized in that the thickness of said polysilicon film is 0.1 microns or more.  
   
   
       4 . A semiconductor pressure sensor according to  claim 1  characterized in that the thickness of said polysilicon film is 0.1 microns and over up to and including 0.4 microns.  
   
   
       5 . A pressure detector comprising; 
 (a) a detector further comprising as an integral unit;    a substrate,    a diaphragm formed on said substrate by sacrificial layer etching method,    a silicon oxide film provided by sealing the etchant filling hole of the sacrificial layer on the said diaphragm, and    a polysilicon film covering part or whole of said silicon oxide film;    (b) a correction circuit for correction of the output of said detector;    (d) a package enclosing said correction circuit and said detector; and    (d) an intake tube provided in said package and used for introduction of external pressure to said detector.    
   
   
       6 . A pressure detector according to  claim 5  characterized in that (h) the distance of said covered part is at least 10 microns or less from said etchant filling hole.  
   
   
       7 . A pressure detector according to  claim 5  characterized in that (i) the thickness of said polysilicon film is 0.1 microns or more.  
   
   
       8 . A pressure detector according to  claim 5  characterized in that (j) the thickness of said polysilicon film is 0.1 microns and over up to and including 0.4 microns.  
   
   
       9 . A pressure detector according to  claim 5  comprising; 
 (e) a sub-package further comprising said correction circuit and said detector as an integral unit, and having on the surface a pad connected to said correction circuit, and    (f) an output terminal removably connected to the external signal line and used to send a signal from said correction circuit to the external signal line;    said pressure detector further characterized in that    (g) said correction circuit and said detector are enclosed by said package after said pad and said output terminal are connected by a metal wire.