Method and apparatus for wafer cleaning

Abstract

An apparatus for wet processing individual wafers comprising; a means for holding the wafer; a means for providing acoustic energy to a non-device side of the wafer; and a means for flowing a fluid onto a device side of the wafer.

1 . An apparatus for processing a wafer, comprising: 
 a bracket for positioning and rotating the wafer about an axis;    a platter aligned beneath and parallel to the bracket, with the platter having a through hole;    a fluid source connected to the through hole for flowing a first chemical within a gap between the wafer and the platter;    one or more nozzles connected to a source of a liquid second chemical for dispensing the liquid second chemical onto the wafer;    a plurality of acoustic wave transducers positioned on the platter that are capable of transmitting a plurality of frequencies;    a means for supplying an input power to each of the plurality of acoustic wave transducers; and    a means for controlling cavitations in the liquid second chemical on the wafer.    
   
   
       2 . The apparatus of  claim 1 , wherein the means for controlling cavitations comprises a means for varying the input power to one or more acoustic waver transducers of the plurality of acoustic wave transducers.  
   
   
       3 . The apparatus of  claim 2 , wherein the means for varying the input power to one or more transducers comprises a means for pulsing the input power.  
   
   
       4 . The apparatus of  claim 3 , wherein the means for pulsing the input power comprises a means for providing a period and a duration of the pulsed input power to correspond to a reduction of acoustic energy reflections between the one or more transducers and the liquid second chemical on the wafer.  
   
   
       5 . The apparatus of  claim 1 , wherein the means for controlling cavitations comprises a means for controlling droplet sizes of the liquid second chemical dispensed on the wafer.  
   
   
       6 . The apparatus of  claim 5 , wherein the means for controlling the droplet sizes of the liquid second chemical comprises a means for entraining a gas into the liquid second chemical.  
   
   
       7 . The apparatus of  claim 6 , wherein the means for entraining a gas into the liquid second chemical comprises a means for injecting the gas under pressure into the source of the liquid second chemical.  
   
   
       8 . The apparatus of  claim 6 , wherein the means for entraining a gas into the liquid second chemical comprises positioning a venturi nozzle, having two main openings and a constriction opening, wherein the main openings are connected between the source of the liquid second chemical and the one or more nozzles for dispensing the liquid second chemical, wherein the gas is supplied to the constriction opening.  
   
   
       9 . The apparatus of  claim 6 , wherein the gas for entraining into the liquid second chemical comprises a gas selected from the group consisting of: H 2 , O 2 , N 2 , Ar, He, and any combination thereof.  
   
   
       10 . An apparatus for controlling cavitation during processing a wafer, comprising: 
 a bracket for positioning and rotating the wafer about an axis;    a platter aligned beneath and parallel to the bracket, with the platter having a through hole;    a fluid source connected to the through hole to flow a first chemical within a gap between the wafer and the platter;    one or more nozzles connected with a source of a liquid second chemical to dispense the liquid second chemical onto the wafer;    a plurality of acoustic wave transducers positioned on the platter that are capable of simultaneously transmitting a plurality of frequencies; and    an electrical wiring connected with the plurality of acoustic wave transducers to supply an input power to the plurality of acoustic wave transducers.    
   
   
       11 . The apparatus of  claim 10 , wherein the plurality of acoustic wave transducers includes a first set of transducers and a second set of transducers.  
   
   
       12 . The apparatus of  claim 11 , wherein the electrical wiring is connected with the first and second set of acoustic wave transducers to send a single signal to the first and second set of acoustic wave transducers.  
   
   
       13 . The apparatus of  claim 12 , wherein the single signal comprises a plurality of different frequencies.  
   
   
       14 . The apparatus of  claim 12 , wherein the first frequency is an integer multiple of the second frequency.  
   
   
       15 . The apparatus of  claim 13 , wherein at least one of the plurality of different frequencies has a different power.  
   
   
       16 . The apparatus of  claim 10 , wherein the electrical wiring is connected with the plurality of acoustic wave transducers and the platter is connected to ground.  
   
   
       17 . The apparatus of  claim 10 , wherein at least one or more nozzle is connected with a gas supply.  
   
   
       18 . The apparatus of  claim 17 , wherein at least one or more nozzle is a venturi nozzle having two main openings and a constriction opening, wherein the main openings are connected between the source of the liquid second chemical and the one or more nozzles for dispensing the liquid second chemical, wherein the gas supply is connected with the constriction opening.