Method and system for supplying carbon dioxide to a semiconductor tool having variable flow requirement

Abstract

Provided is a novel method and system for supplying high-pressure carbon dioxide to an application having a variable carbon dioxide flow requirement. The method includes providing a high-pressure carbon dioxide feed stream to a buffer volume and determining the amount of carbon dioxide to be delivered to the application tool. The pressure in the buffer volume is maintained at a pressure that exceeds the pressure required by the application tool. The temperature in the buffer volume is further adjusted to modify the density of the carbon dioxide and based thereon the size of the buffer volume. Thereafter, the carbon dioxide from the buffer volume is delivered at a variable flow rate as required by the application tool.

1 . A method for supplying high-pressure carbon dioxide to an application tool having a variable carbon dioxide flow requirement, comprising: 
 providing a high-pressure carbon dioxide feed stream to a buffer volume;    maintaining the pressure in said buffer volume between a minimum pressure that exceeds the pressure required by said application tool and a maximum pressure such that the average density of carbon dioxide contained in said buffer volume at said minimum pressure is different from the average density of carbon dioxide contained in said buffer volume at said maximum pressure;    adjusting the average temperature in said buffer volume to modify the difference between the average density of carbon dioxide contained in said buffer volume at said minimum pressure and the average density of carbon dioxide contained in said buffer volume at said maximum pressure such that the flow requirement associated with said application tool is satisfied; and    delivering a high-pressure carbon dioxide supply stream from said buffer volume at a variable flow rate as required by the application tool.    
   
   
       2 . The method according to  claim 1 , further comprising: 
 reducing the buffer volume requisite to deliver a predetermined amount of carbon dioxide to the application tool based on the temperature adjustments to the buffer volume.    
   
   
       3 . The method according to  claim 1 , wherein the flow requirement to the application tool is discontinuous.  
   
   
       4 . The method according to  claim 1 , wherein the application tool is a semiconductor application tool.  
   
   
       5 . The method according to  claim 1 , wherein the carbon dioxide requisite for delivery to the application tool is predetermined.  
   
   
       6 . The method according to  claim 1 , wherein said buffer volume is at least one pressure vessel.  
   
   
       7 . The method according to  claim 1 , further comprising: heating or cooling the carbon dioxide contained in said buffer volume via a heating or cooling device.  
   
   
       8 . The method according to  claim 1 , further comprising: heating or cooling said high pressure carbon dioxide feed stream via a heating or cooling device.  
   
   
       9 . The method according to  claim 1 , further comprising: heating or cooling said high-pressure carbon dioxide supply stream via a heating or cooling device to the temperature desired at the application tool.  
   
   
       10 . The method according to  claim 1 , further comprising: withdrawing a portion of carbon dioxide contained in said buffer volume, heating or cooling said portion via a heating or cooling device and returning said portion to said buffer volume.  
   
   
       11 . The method according to  claim 1 , wherein the high pressure carbon dioxide feed stream is single-phase carbon dioxide.  
   
   
       12 . The method according to  claim 1 , further comprising: generating the high pressure carbon dioxide feed stream from a bulk storage tank disposed upstream of said buffer volume.  
   
   
       13 . The method according to  claim 1 , further comprising: purifying the high pressure carbon dioxide feed stream upstream of said buffer volume in a purification system.  
   
   
       14 . The method according to  claim 13 , wherein said purification system includes at least one particulate filter.  
   
   
       15 . The method according to  claim 13 , wherein the temperature associated with the purification system is greater than the temperature in the buffer volume.  
   
   
       16 . The method according to  claim 15 , further comprising: routing the high temperature carbon dioxide stream exiting the purification system to a heat exchanger wherein part of the heat contained in said high temperature carbon dioxide stream is recovered.  
   
   
       17 . The method according to  claim 16 , wherein said high temperature carbon dioxide stream is routed to a heat exchanger upstream of the buffer volume producing a lower temperature carbon dioxide stream and a first portion of said lower temperature carbon dioxide stream is routed to the buffer volume while a second portion is recirculated to the bulk storage tank.  
   
   
       18 . The method according to  claim 16 , wherein the heat contained in said high temperature carbon dioxide stream is recovered in a single heat exchanger.  
   
   
       19 . A system for supplying high-pressure carbon dioxide to an application having a variable carbon dioxide flow requirement, comprising: 
 a buffer volume to receive a high-pressure carbon dioxide feed stream, wherein the pressure in said buffer volume is maintained between a minimum pressure that exceeds the pressure required by said application tool and a maximum pressure such that the density of said carbon dioxide at said minimum pressure is different from the density of said carbon dioxide at said maximum pressure, and the temperature in said buffer volume is adjusted;    a carbon dioxide purification unit disposed upstream of said buffer volume to deliver a high-pressure carbon dioxide feed stream; and    an application tool disposed downstream of said buffer volume to receive carbon dioxide from said buffer volume at a variable flow rate as required by the application tool.    
   
   
       20 . The system according to  claim 19 , further comprising: 
 a high-pressure carbon dioxide feed stream heating or cooling device disposed downstream of said carbon dioxide purification unit.    
   
   
       21 . The system according to  claim 19 , further comprising: 
 a carbon dioxide pressurization device disposed upstream of the purification unit to provide carbon dioxide supplied from a bulk storage tank.