Optical sensor system and method for detection of hydrides and acid gases

Abstract

A gas sensor for detection of hydride and/or acid gas species, featuring a color changing material that changes color in exposure to hydride and/or acid gas species, component(s) for impinging radiation on the color changing material for reflection therefrom, and component(s) for receiving reflected radiation from the color changing material and responsively generating an output upon a change of color of the color changing material indicative of a presence of hydride and/or acid gas species in gas contacting the color changing material. The gas sensor may be embodied in a compact and efficient probe assembly, utilizing optical fibers to transmit incident radiation to the color changing material and to transmit reflected radiation to a detector and signal processing circuitry.

1 - 52 . (canceled)  
     
     
         53 . A method of determining the concentration of hydride and/or acid gas species in a gaseous medium, said method comprising: 
 providing an elongated sensor body with a light-transmissive window affixed to a distal end portion thereof, said light-transmissive window defining a first side exterior to said elongated sensor body and a second side interior to said elongated sensor body and having a color changing material at the first side thereof that changes color in exposure to the hydride and/or acid gas species;    contacting the gaseous medium with a color changing material at the first, exterior side of said light-transmissive window, while impinging on the color changing material an incident radiation from the second, interior side of the light-transmissive window, so that such incident radiation transmits through said window to the color changing material and is reflected from said color changing material;    monitoring the reflected radiation from the color changing material through said light-transmissive window to detect a change of the reflected radiation indicative of a change of color of the color changing material due to presence of an amount of hydride and/or acid gas species in said gaseous medium; and    comparing the change of the reflected radiation to a pre-determined relationship between the change of reflected radiation and the concentration of hydride and/or acid gas species present to quantitate the amount of hydride and/or acid gas species in the gaseous medium.    
     
     
         54 . The method of  claim 53 , further comprising generating an output from said monitoring upon quantitation of the concentration of hydride and/or acid gas species.  
     
     
         55 . The method of  claim 53 , wherein the color changing material comprises a material selected from the group consisting of: 
 (1) hydride gas detection materials comprising a material selected from the group consisting of silver nitrate, metal hydroxides, metal carbonates, metal sulfates, mercury chloride (HgCl 2 ), gold (Au +3 ) complexes, and color indicating dosimeter hydride detection materials; and    (II) acid gas detection materials comprising material selected from the group consisting of iron oxide and acid/base indicators.    
     
     
         56 . The method of  claim 53 , wherein the color changing material comprises a material selected from the group consisting of silver nitrate, metal hydroxides, metal carbonates, metal sulfates, mercury chloride (HgCl 2 ) and gold (Au +3 ) complexes.  
     
     
         57 . The method of  claim 53 , wherein the color changing material comprises a material selected from the group consisting of iron oxide, methyl orange, bromocresol green, methyl red, bromocresol purple, bromothymal blue, and phenol red.  
     
     
         58 . The method of  claim 53 , wherein the gaseous medium comprises an effluent from a semiconductor manufacturing operation.  
     
     
         59 . The method of  claim 58 , wherein the hydride and/or acid gas species comprises at least one species selected from the group consisting of boranes, arsine, phosphine, silane, F 2 , HF, HCl, chlorine, Br 2 , ClF 3 , SiF 4 , Br 2 , HBr, HI, BF 3 , BCl 3 , and H n SiCl (n-4)  (wherein n=1 to 3, inclusive).  
     
     
         60 . The method of  claim 59 , wherein the color changing material is positioned to contact gaseous medium in a discharge end portion of a dry scrubber bed.  
     
     
         61 . The method of  claim 59 , wherein the color changing material is positioned to contact gaseous medium discharged from a scrubber unit.  
     
     
         62 . The method of  claim 59 , wherein the color changing material is positioned to contact gaseous medium in a gas cabinet.  
     
     
         63 . The method of  claim 53 , wherein the hydride and/or acid gas species is for use in a semiconductor manufacturing plant.