Methods and apparatus for filling features in microfeature workpieces

Abstract

Methods and apparatus for filling features on microfeature workpieces. One embodiment of a method for filling features on a microfeature workpiece comprises contacting a surface of the microfeature workpiece with a plating solution having a plating species and an accelerator, and electrochemically depositing the plating species onto the workpiece until the plating species at least substantially fills first depressions on the workpiece. The electrochemical species forms a plated layer on the workpiece, and this method further includes changing the concentration of the accelerator on a surface of the plated layer at locations aligned with the first depressions. The method continues by electroplating more of the plating species onto the workpiece after changing the concentration of the accelerator on the plated layer to further deposit the plating species into a second depression on the microfeature workpiece that is larger than the first depression.

1 . A method of filling features on microfeature workpieces, comprising: 
 contacting a surface of a microfeature workpiece with a plating solution that includes a plating species and an accelerator for enhancing deposition of the plating species in depressions on the workpiece;    filling first depressions on the workpiece with the plating species by electrochemically depositing the plating species onto the workpiece to form a plated layer that at least substantially fills the first depressions on the workpiece;    reducing a concentration of the accelerator accumulated on a surface of the plated layer after the plated layer at least substantially fills the first depressions; and    electroplating more of the plating species onto the workpiece after reducing the concentration of the accelerator on the surface of the plated layer.    
   
   
       2 . The method of  claim 1  wherein the first depressions have a first width and the workpiece further comprises a second depression having a second width larger than the first width, and wherein filling the first depressions comprises completely filling the first depressions with the plating species without completely filling the second depression with the plating species before reducing the concentration of the accelerator on the surface of the plated layer.  
   
   
       3 . The method of  claim 1  wherein: 
 the first depressions have a first width and the workpiece further comprises a second depression having a second width larger than the first width;    filling the first depressions comprises electroplating the plating species onto the workpiece using a forward electrical bias until the plating species completely fills the first depressions without completely filling the second depression; and    reducing the concentration of the accelerator comprises reversing the electrical bias to de-plate the plating species from the workpiece.    
   
   
       4 . The method of  claim 3  wherein de-plating the plating species from the workpiece comprises removing approximately 3 Å to 100 Å of the plated layer, and electroplating more of the plating species comprises filling the second depression with the plating species after de-plating.  
   
   
       5 . The method of  claim 1  wherein: 
 the first depressions have a first width and the workpiece further comprises a second depression having a second width larger than the first width;    filling the first depressions comprises electroplating the plating species onto the workpiece using a forward electrical bias until the plating species completely fills the first depressions without completely filling the second depression with the plating species; and    reducing the concentration of the accelerator comprises de-plating a portion of the plated layer from the workpiece.    
   
   
       6 . The method of  claim 5  wherein electroplating more of the plated species onto the workpiece comprises filling the second depression with the plating species after de-plating a portion of the plated layer from the workpiece.  
   
   
       7 . The method of  claim 5  wherein the plating species comprises copper, and wherein electrochemically depositing the plating species onto the workpiece comprises electrolessly plating copper into the first depressions.  
   
   
       8 . The method of  claim 5  wherein the plating species comprises copper, and wherein electrochemically depositing the plating species onto the workpiece comprises electroplating the copper into the first depressions.  
   
   
       9 . A method of filling features on microfeature workpieces having first features with a first dimension and second features with a second dimension greater than the first dimension, comprising: 
 contacting a surface of a microfeature workpiece with a plating solution having a plating species and an accelerator;    electrochemically depositing the plating species onto the workpiece to form a plated layer that at least substantially occupies the first features of the workpiece;    removing accumulations of the accelerator from a surface of the plated layer; and    electroplating more of the plating species onto the workpiece after removing the accumulations of the accelerator to bulk plate the plating species into the second features.    
   
   
       10 . The method of  claim 9  wherein electrochemically depositing the plating species onto the workpiece to form a plated layer comprises completely filling the first features with the plating species without completely filling the second features before removing the accumulations of the accelerator from the surface of the plated layer.  
   
   
       11 . The method of  claim 10  wherein removing the accumulations of the accelerator from the surface of the plated layer comprises de-plating material from the plated layer.  
   
   
       12 . The method of  claim 9  wherein removing the accumulations of the accelerator from the surface of the plated layer comprises de-plating material from the plated layer.  
   
   
       13 . The method of  claim 12  wherein de-plating material from the plated layer comprises removing approximately 3 Å to approximately 100 Å of the plated layer.  
   
   
       14 . The method of  claim 9  wherein electrochemically depositing the plating species comprises electrolessly plating copper into the first features.  
   
   
       15 . The method of  claim 9  wherein electrochemically depositing the plating species onto the workpiece to form a plated layer comprises electroplating copper into the first features.  
   
   
       16 . A method of filling features on microfeature workpieces having first depressions with a first dimension and a second depression with a second dimension greater than the first dimension, comprising: 
 contacting a surface of a microfeature workpiece with a plating solution having a plating species and an accelerator;    electrochemically depositing the plating species onto the workpiece until the plating species at least partially fills the first depressions;    changing a concentration of the accelerator on a surface of a plated layer at locations aligned with the first depressions; and    electroplating more of the plating species onto the workpiece after changing the concentration of the accelerator on the surface of the plated layer.    
   
   
       17 . The method of  claim 16  wherein electrochemically depositing the plating species onto the workpiece comprises completely filling the first depressions with the plating species without completely filling the second depression.  
   
   
       18 . The method of  claim 16  wherein electrochemically depositing the plating species onto the workpiece comprises filling the first depressions by electroplating the plating species onto the workpiece using a forward electrical bias.  
   
   
       19 . The method of  claim 18  wherein changing a concentration of the accelerator on the surface of the plated layer comprises applying a reverse electrical bias to the workpiece.  
   
   
       20 . The method of  claim 18  wherein changing a concentration of the accelerator on the surface of the plated layer comprises applying a reverse electrical bias to the workpiece to de-plate a portion of the plating layer.  
   
   
       21 . The method of  claim 16  wherein changing a concentration of the accelerator on the surface of the plated layer comprises de-plating a portion of the plated layer.  
   
   
       22 . The method of  claim 21  wherein de-plating a portion of the plating layer comprises removing approximately 3 Å to 100 Å of the plated layer.  
   
   
       23 . The method of  claim 16  wherein electrochemically depositing the plating species onto the workpiece comprises electrolessly plating copper into the first depressions.  
   
   
       24 . The method of  claim 16  wherein electrochemically depositing the plating species onto the workpiece comprises electroplating copper into the first depressions.  
   
   
       25 . A method of filling features on microfeature workpieces having first depressions with a first dimension and a second depression with a second dimension greater than the first dimension, comprising: 
 contacting a surface of a microfeature workpiece with a plating solution having a plating species and an accelerator;    electrochemically depositing the plating species onto the workpiece until the plating species fills the first depressions to form a plated layer on the workpiece;    electrochemically removing (a) accumulations of the accelerator from a surface of the plated layer and (b) a portion of the plated layer to produce a reconditioned surface on the plated layer; and    electroplating more of the plating species onto the restored surface of the plated layer to increase the thickness of the plated layer.    
   
   
       26 . The method of  claim 25  wherein electrochemically depositing the plating species under the workpiece comprises electrolessly plating copper into the first depressions.  
   
   
       27 . The method of  claim 25  wherein electrochemically depositing the plating species under the workpiece comprises electroplating copper into the first depressions.  
   
   
       28 . The method of  claim 25  wherein electrochemically removing the accumulations of the accelerator from the surface of the plated layer and a portion of the plated layer to produce a reconditioned surface comprises de-plating material from the plated layer.  
   
   
       29 . The method of  claim 28  wherein de-plating material from the plated layer comprises applying a reverse electrical bias to the workpiece.  
   
   
       30 . A system for filling features on microfeature workpieces having first features with a first size and a second feature with a second size greater than the first size, comprising: 
 a workpiece holder having electrical contacts configured to contact a surface of the workpiece;    a plating vessel configured to contain a plating solution having a plating species and an accelerator;    a counter electrode in the plating vessel;    a power source coupled to the electrical contacts and the counter electrode to establish an electrical field through the plating solution in the plating vessel for electrochemically processing the workpiece; and    a controller coupled to the power source, wherein the controller includes a computer operable medium that contains instructions which cause the power source to (a) electrochemically deposit the plating species onto the workpiece until the plating species at least substantially fills the first features, (b) change the concentration of the accelerator on a surface of a plated layer of the plating species at locations aligned with the first features, and (c) electroplate more of the plating species onto the workpiece after changing the concentration of the accelerator on the surface of the plated layer.    
   
   
       31 . A system for filling features on microfeature workpieces having first depressions with a first size and a second depression with a second size greater than the first size, comprising: 
 a workpiece holder having electrical contacts configured to contact a surface of the workpiece;    a plating vessel configured to contain a plating solution having a plating species and an accelerator;    a counter electrode in the plating reactor;    a power source coupled to the electrical contacts and the counter electrode to establish an electrical field in the plating vessel that electrochemically processes the workpiece; and    a controller coupled to the power source, wherein the controller includes a computer operable medium that contains instructions which cause the power source to (a) electrochemically deposit the plating species onto the workpiece to form a plated layer that fills the first depressions, (b) electrochemically remove accumulations of the accelerator from a surface of the plated layer and a portion of the plated layer to produce a restored surface on the plated layer, and (c) electroplate more of the plating species onto the restored surface of the plated layer.