Chemical dispense system

Abstract

The performance of photolithography chemical dispense apparatus is improved by placing the chemical filter before the dispense pump and providing a separate pressure control for the filter. This approach allows the system to utilize both an optimal dispense rate and an optimal filtration rate. A chemical source can have a first pressure source applied, and a second pressure source applied where necessary to control the filtration rate. The pressures can be optimized during calibration, and optimal pressures can be maintained using pressure sensors that monitor the pressures. A controller can model the behavior of at least the dispense pressure during a dispense cycle and can calculate an adjustment function to be applied to the dispense pump during a subsequent dispense cycle in order to optimize the dispense pressure (and hence flow rate) during each cycle.

1 . A method of dispensing a flow of photolithography chemical onto a substrate, comprising: 
 directing a flow of photolithography chemical into a buffer vessel for providing a continuous source of the photolithography chemical for a dispense cycle;    applying a flow of pressurized fluid to the buffer vessel in order to push the photolithography chemical out of the buffer vessel to a chemical filter;    directing the photolithography chemical through a chemical filter at substantially a predetermined flow rate;    directing the filtered photolithography chemical to a dispense pump operable to direct the filtered photolithography chemical out of the dispense pump at a controlled flow rate using a selected flow rate function; and    dispensing the photolithography chemical onto the substrate at substantially the controlled flow rate.    
   
   
       2 . A method according to  claim 1 , wherein: 
 directing the photolithography chemical through a chemical filter includes suctioning the photolithography chemical through the filter using the dispense pump.    
   
   
       3 . A method according to  claim 1 , wherein: 
 the controled flow rate is substantially an optimal dispense flow rate.    
   
   
       4 . A method according to  claim 1 , wherein: 
 the photolithography chemical is at least one of a bottom anti-reflective coating (BARC), top antireflective coating (TARC), spin on dielectric (SOD), spin on polymer (SOP), and top coat (TC).    
   
   
       5 . A method of dispensing a selected flow of photolithography chemical onto a substrate, comprising: 
 directing a flow of the photolithography chemical through a chemical filter at a preselected flow rate;    directing the filtered flow of the photolithography chemical through a dispense pump in order to direct the filtered flow of the photolithography chemical to a dispense nozzle at a controlled flow rate using a selected flow rate function;    monitoring a variation in pressure of the photolithography chemical adjacent the dispense nozzle while dispensing the photolithography chemical onto the substrate;    determining dispense adjustments for at least two values of the monitored pressure variation; and    adjusting the operation of the dispense pump for a subsequent substrate according to the determined dispense adjustments.    
   
   
       6 . A method according to  claim 5 , wherein: 
 directing a flow of the photolithography chemical through a chemical filter directs the flow at substantially an optimal filtration rate.    
   
   
       7 . A method according to  claim 5 , wherein: 
 directing the filtered flow of the photolithography chemical through a dispense pump directs the photolithography chemical out of the dispense pump at a controlled flow rate that is substantially an optimal dispense flow rate function.    
   
   
       8 . A system for dispensing a flow of photolithography chemical onto a substrate, comprising: 
 a buffer vessel configured to receive a flow of photolithography chemical and provide a continuous source of photolithography chemical during a dispense process;    a pressure source operable to apply a flow of pressurized fluid to the buffer vessel in order to provide the photolithography chemical at a controlled pressure;    a chemical filter configured to receive and filter the photolithography chemical at substantially a preselected flow rate;    a dispense pump operable to receive the filtered photolithography chemical at substantially the preselected flow rate and direct the filtered photolithography chemical out of the dispense pump at a controlled flow rate using a selected flow rate function; and    a nozzle for receiving the filtered photolithography chemical and dispensing the filtered photolithography chemical onto the substrate at substantially the controlled flow rate.    
   
   
       9 . A system according to  claim 8 , wherein: 
 the preselected flow rate is substantially an optimal filtration rate.    
   
   
       10 . A system according to  claim 8 , wherein: 
 the controlled flow rate is substantially an optimal dispense flow rate.    
   
   
       11 . A system according to  claim 8 , further comprising: 
 a chemical source for supplying the photolithography chemical.    
   
   
       12 . A system according to  claim 11 , further comprising: 
 an additional pressure source operable to apply an additional flow of pressurized fluid to the chemical source in order to push the photolithography chemical out of the chemical source.    
   
   
       13 . A system for dispensing a flow of photolithography chemical onto a substrate, comprising: 
 a pressure source operable to apply a flow of pressurized fluid in order to provide photolithography chemical at a controlled pressure;    a chemical filter configured to receive and filter the photolithography chemical at substantially a preselected flow rate;    a dispense pump operable to receive the filtered photolithography chemical at substantially the preselected flow rate and direct a flow of filtered photolithography chemical out of the dispense pump at a controlled flow rate using a selected flow rate function;    a nozzle for receiving the filtered photolithography chemical and dispensing the filtered photolithography chemical onto the substrate at substantially the controlled flow rate; and    a system controller operable to monitor a variation in pressure of the filtered photolithography chemical near the nozzle while dispensing the photolithography chemical onto the substrate, the system controller being further operable to determine dispense adjustments for at least two values of the monitored pressure variation and adjust the operation of the dispense pump for a subsequent substrate according to the determined dispense adjustments.    
   
   
       14 . A system according to  claim 13 , wherein: 
 the preselected flow rate is substantially an optimal filtration rate.    
   
   
       15 . A system according to  claim 13 , wherein: 
 the controlled flow rate is substantially an optimal dispense rate.    
   
   
       16 . A system according to  claim 13 , further comprising: 
 a chemical source for supplying the photolithography chemical.    
   
   
       17 . A system according to  claim 16 , further comprising: 
 an additional pressure source operable to apply an additional flow of pressurized fluid to the chemical source in order to push the photolithography chemical out of the chemical source.    
   
   
       18 . A system according to  claim 17 , further comprising: 
 a buffer vessel configured to receive the flow of photolithography chemical from the chemical source and provide a continuous source of the photolithography chemical for a dispense process.    
   
   
       19 . A system according to  claim 13 , wherein: 
 the system controller is further operable to determine an adjustment function from the determined dispense adjustments and adjust the operation of the dispense pump for a subsequent substrate according to the adjustment function.    
   
   
       20 . A computer program product stored on a computer-readable storage medium for dispensing a flow of photolithography chemical onto a substrate, the computer program product comprising: 
 computer program code for directing a flow of the photolithography chemical through a chemical filter at a preselected flow rate;    computer program code for directing the filtered flow of the photolithography chemical received from the filter from a dispense pump to a dispense nozzle at a controlled flow rate using a selected flow rate function;    computer program code for monitoring a variation in pressure of the photolithography chemical near the dispense nozzle while dispensing the photolithography chemical onto the substrate;    computer program code for determining dispense adjustments for at least two values of the monitored pressure variation; and    computer program code for adjusting the operation of the dispense pump for a subsequent substrate according to the determined dispense adjustments.