Pressure sensor and substrate processing apparatus

Abstract

A pressure sensor comprises a thin disk-shaped diaphragm, a laser displacement meter for detecting an amount of deformation of the diaphragm, and an operation part connected to the laser displacement meter. In the pressure sensor, an amount of deformation of the diaphragm due to pressure of fluid flowing into the pressure sensor is detected by the laser displacement meter, and pressure of the fluid is obtained on the basis of the amount of deformation and conversion information stored in the operation part in advance. The base part of the diaphragm of the pressure sensor is made of graphite (or silicon substrate), and a thin film of silicon carbide which is in contact with fluid is formed on a surface of the base part. This improves chemical resistance to the pressure sensor and extends the lifetime of the pressure sensor while preventing metal elution.

1 . A pressure sensor, comprising:
 a pressure chamber filled with fluid whose pressure is to be measured;   a thin-plate diaphragm which is elastically deformed according to pressure of fluid in said pressure chamber, a part of said diaphragm, which is in contact with said fluid, being made of silicon carbide, glassy carbon, or diamond; and   a detection mechanism for detecting an amount of deformation of said diaphragm.   
   
   
       2 . The pressure sensor according to  claim 1 , wherein
 a base part of said diaphragm is made of graphite, and   a thin film of silicon carbide which is in contact with fluid in said pressure chamber is formed on a surface of said base part.   
   
   
       3 . The pressure sensor according to  claim 1 , wherein
 a base part of said diaphragm is a silicon substrate, and   a thin film of silicon carbide which is in contact with fluid in said pressure chamber is formed on a surface of said base part.   
   
   
       4 . The pressure sensor according to  claim 1 , wherein
 said detection mechanism detects an amount of deformation of said diaphragm without being in contact with said diaphragm.   
   
   
       5 . The pressure sensor according to  claim 4 , wherein
 said detection mechanism emits a light beam to said diaphragm and detects a light receiving position of said light beam reflected on said diaphragm, to detect an amount of deformation of said diaphragm.   
   
   
       6 . The pressure sensor according to  claim 4 , wherein
 said detection mechanism detects an amount of deformation of said diaphragm on the basis of a capacitance between a first electrode provided on one surface of said diaphragm, the opposite surface of which faces said pressure chamber, and a second electrode facing said first electrode without in contact with said first electrode.   
   
   
       7 . The pressure sensor according to  claim 1 , further comprising:
 channels for replacing gas in a space isolated from said pressure chamber by said diaphragm with external air.   
   
   
       8 . The pressure sensor according to  claim 1 , wherein
 said fluid contains at least one of HF, HCl, HNO 3 , H 2 SO 4 , H 2 O 2 , and NH 4 OH.   
   
   
       9 . The pressure sensor according to  claim 1 , further comprising
 an operation part for storing conversion information representing a relationship between an amount of deformation of said diaphragm and pressure of said fluid, and obtaining pressure of said fluid on the basis of said conversion information and an amount of deformation of said diaphragm detected by said detection mechanism.