Liquid level sensor for a chemical source vessel

Abstract

A chemical vessel used for holding a liquid chemical precursor is disclosed comprising a liquid level sensor tube. The liquid level sensor tube is configured to operate in an environment where the liquid chemical precursor is heated to a point of boiling or vaporization. The liquid level sensor tube comprises housing with a slot built in to prevent any false readings of sensors disposed within the liquid level sensor tube.

1 . A liquid level sensor tube for use in determining a level of a liquid chemical precursor in a chemical vessel, the liquid level sensor tube comprising:
 a housing configured to be disposed in the chemical vessel and extend a depth into the chemical vessel, the housing having an outer surface configured to be in direct contact with the liquid chemical precursor, and having a sealed and dry environment inside the housing protected from the liquid chemical precursor, the housing outer surface comprising an open channel that projects radially inwardly into the housing and that extends substantially an entire vertical length of the housing for accommodating placement of the liquid chemical precursor therein; and   at least one pair of sensors disposed in the sealed and dry environment inside the housing and comprising a first sensor in contact with the housing and positioned opposite from a second sensor in contact with the housing, wherein the first and second sensors are positioned at opposite sides of the open channel, wherein the at least one pair of sensors is positioned in the housing at a determined vertical location of the liquid level sensor tube associated with a determined level of the liquid chemical precursor in the chemical vessel, wherein the at least one pair of sensors is configured to determine the level of the liquid chemical precursor in the open channel from within the sealed and dry environment inside of the housing without contacting the liquid chemical precursor.   
     
     
         2 . The liquid level sensor tube of  claim 1 , wherein the housing comprises an outer housing portion connected to an inner housing portion, and wherein the at least one pair of sensors is in contact with opposite inside wall surfaces of the inner housing portion that form the open channel therebetween. 
     
     
         3 . The liquid level sensor tube of  claim 1 , comprising at least two pairs of sensors, wherein each pair of sensors comprises two sensors and is positioned at different vertical locations along the liquid level sensor tube that are associated with different determined levels of the chemical precursor in the chemical vessel. 
     
     
         4 . The liquid level sensor tube of  claim 1 , wherein the open channel is U-shaped. 
     
     
         5 . A chemical vessel, comprising:
 a vessel housing comprising a liquid level sensor port and a bottom recess recessed into a bottom surface of the vessel housing; and   a liquid level sensor tube extending from a top of the vessel housing into the vessel housing, wherein a portion of the liquid level sensor tube is disposed within the bottom recess of the vessel housing, the liquid level sensor tube comprising:
 a liquid level sensor tube housing comprising an outer surface configured to be in direct contact with a liquid chemical precursor disposed in the vessel housing and a sealed and dry environment inside the housing that is protected from the chemical precursor, wherein the liquid level sensor tube housing comprises a slot that extends a length of the liquid level sensor tube housing; and 
 a plurality of sensors disposed within the liquid level sensor tube housing in the sealed and dry environment and located at one or more vertical locations along the liquid level sensor tube associated with particular levels of the liquid chemical precursor in the vessel housing. 
   
     
     
         6 . The chemical vessel of  claim 5 , wherein the slot extends a majority of an entire length of the liquid level sensor tube housing. 
     
     
         7 . The chemical vessel of  claim 6 , wherein the slot extends substantially the entire length of the liquid level sensor tube housing. 
     
     
         8 . The chemical vessel of  claim 5 , wherein one of the plurality of sensors in the liquid level sensor tube is disposed in the bottom recess of the vessel housing. 
     
     
         9 . The chemical vessel of  claim 5 , wherein the liquid level sensor tube housing comprises an outer housing portion connected with an inner housing portion, and wherein at least one of the plurality of sensors is in contact with an inside wall surface of the inner housing portion of the liquid level sensor tube housing. 
     
     
         10 . The chemical vessel of  claim 5 , wherein the plurality of sensors comprises at least one pair of sensors in contact with the housing, wherein a first sensor and a second sensor of the pair of sensors are positioned at opposite sides of the channel. 
     
     
         11 . The chemical vessel of  claim 5 , wherein the plurality of sensors comprises at least two pairs of sensors, wherein each pair of sensors comprises two sensors and is positioned at different vertical locations along the liquid level sensor tube that are associated with different determined levels of the chemical precursor in the vessel housing. 
     
     
         12 . The chemical vessel of  claim 5 , wherein the slot has at least one of a rounded cross-sectional shape, a rectangular cross-sectional shape, or a triangular cross-sectional shape. 
     
     
         13 . A reaction system for depositing a semiconductor film onto a substrate, the reaction system comprising:
 a chemical vessel, comprising:
 a vessel housing comprising a liquid level sensor port and a bottom recess recessed into a bottom surface of the vessel housing; and 
 a liquid level sensor tube extending from a top of the vessel housing into the vessel housing, wherein a portion of the liquid level sensor tube is disposed within the bottom recess of the vessel housing, the liquid level sensor tube comprising:
 a liquid level sensor tube housing comprising an outer surface configured to be in direct contact with a liquid chemical precursor disposed in the vessel housing and a sealed and dry environment inside the housing that is protected from the chemical precursor, wherein the liquid level sensor tube housing comprises a slot that extends a length of the liquid level sensor tube housing; and 
 a plurality of sensors disposed within the liquid level sensor tube housing in the sealed and dry environment and located at one or more vertical locations along the liquid level sensor tube associated with particular levels of the liquid chemical precursor in the vessel housing. 
 
   
     
     
         14 . The reaction system of  claim 13 , wherein the slot extends a majority of an entire length of the liquid level sensor tube housing. 
     
     
         15 . The reaction system of  claim 14 , wherein the slot extends substantially the entire length of the liquid level sensor tube housing. 
     
     
         16 . The reaction system of  claim 13 , wherein one of the plurality of sensors in the liquid level sensor tube is disposed in the bottom recess of the vessel housing. 
     
     
         17 . The reaction system of  claim 13 , wherein the liquid level sensor tube housing comprises an outer housing portion connected with an inner housing portion, and wherein at least one of the plurality of sensors is in contact with an inside wall surface of the inner housing portion of the liquid level sensor tube housing. 
     
     
         18 . The reaction system of  claim 13 , wherein the plurality of sensors comprises at least one pair of sensors in contact with the housing, wherein a first sensor and a second sensor of the pair of sensors are positioned at opposite sides of the channel. 
     
     
         19 . The reaction system of  claim 13 , wherein the plurality of sensors comprises at least two pairs of sensors, wherein each pair of sensors comprises two sensors and is positioned at different vertical locations along the liquid level sensor tube that are associated with different determined levels of the chemical precursor in the vessel housing. 
     
     
         20 . The reaction system of  claim 13 , wherein the slot has at least one of a rounded cross-sectional shape, a rectangular cross-sectional shape, or a triangular cross-sectional shape.