Method and process for improved uniformity of electrochemical plating films produced in semiconductor device processing

Abstract

A method and device for ECP copper deposition into openings and over a surface of a semiconductor substrate provides a final deposited film with a uniform height across the substrate. The substrate is submerged in an ECP electrolyte solution with accelerants formed on a dielectric surface and in and over damascene openings formed in the dielectric surface, and copper is deposited onto the surface and into the damascene openings. A deplating process that uses a reverse polarity of power conditions used in the ECP process is then used for a brief time to remove some of the deposited copper and an excess portion of the accelerant. The copper is preferentially removed from portions where the initial deposition produced localized thick portions and the deplating process is followed by a further ECP process that yields a copper film with a uniform top surface.

1 . An electrochemical plating (ECP) method comprising: 
 providing a substrate with a surface;    providing accelerants on the surface;    depositing copper on the surface by ECP in which the substrate is submerged in an ECP electrolyte solution;    deplating whereby some copper and an excess portion of the accelerants are removed; and    further depositing copper over the surface by ECP in which the substrate is submerged in the ECP electrolyte solution and the copper includes an upper surface that is essentially uniform in elevation with respect to the surface.    
   
   
       2 . The method as in  claim 1 , wherein the accelerants are a component of the ECP electrolyte solution and the providing accelerants and the depositing copper take place substantially simultaneously.  
   
   
       3 . The method as in  claim 1 , wherein the deplating takes place for a time of about 5 seconds.  
   
   
       4 . The method of  claim 1 , wherein the providing a substrate includes the substrate including openings extending downwardly from the surface, the depositing copper includes depositing copper in the openings and the deplating is initiated about when the openings become filled with copper.  
   
   
       5 . The method of  claim 1 , wherein the providing a substrate includes openings extending downwardly from the surface, and wherein the excess portion of the accelerants lies above the openings.  
   
   
       6 . The method as in  claim 5 , wherein the deplating removes more copper from over the openings than from other areas of the substrate surface.  
   
   
       7 . The method as in  claim 1 , wherein the depositing, the deplating, and the further depositing take place in-situ and wherein the deplating uses a reverse polarity of power used in the depositing and the further depositing.  
   
   
       8 . The method as in  claim 1 , wherein the depositing forms a non-uniform copper layer and the deplating results in a substantially uniform copper layer.  
   
   
       9 . An electrochemical plating (ECP) method comprising: 
 providing a substrate in an ECP electrolyte solution; and    plating copper on a surface using an ECP operation that includes a sequence of a forward polarity first plating step followed by an in-situ reverse polarity deplating step followed by an in-situ forward polarity second plating step, the forward polarity steps having a forward power and the reverse polarity step having a reverse power.    
   
   
       10 . The method as in  claim 9 , wherein the reverse polarity deplating step takes place for a time within a range of 3 to 12 seconds.  
   
   
       11 . The method as in  claim 9 , wherein the ECP electrolyte solution includes accelerants therein and the reverse polarity deplating step removes an excess portion of the accelerants from the surface.  
   
   
       12 . An electrochemical plating (ECP) method comprising: 
 providing a semiconductor substrate with a dielectric layer having an upper surface and openings extending downwardly from the upper surface;    depositing copper at least in the openings using an ECP operation;    when the openings are substantially filled, performing a deplating operation that removes some of the copper; and    further depositing copper at least over the openings and over the upper surface.    
   
   
       13 . The method as in  claim 12 , wherein the depositing copper at least in the openings using an ECP operation includes submerging the substrate in an ECP electrolyte solution that further includes an accelerant, and wherein the deplating process removes excess portions of the accelerant.  
   
   
       14 . The method as in  claim 13 , wherein the accelerant accumulates around the openings during the depositing copper and the deplating produces a substantially uniform concentration of accelerant across the substrate.  
   
   
       15 . The method as in  claim 12 , wherein the deplating process takes place for about 5 seconds.  
   
   
       16 . The method as in  claim 12 , wherein the openings include extend to a conductive bottom and the openings comprise at least one of trenches and vias.  
   
   
       17 . The method as in  claim 12 , wherein the deplating process is performed in-situ with the depositing and the further depositing, and the deplating process includes a reverse polarity of a power applied in the depositing and in the further depositing.  
   
   
       18 . The method as in  claim 12 , wherein the further depositing copper produces copper filling the openings and over the upper surface such that the copper has a top surface of substantially uniform height.  
   
   
       19 . The method as in  claim 12 , wherein the depositing copper includes depositing copper over the upper surface.  
   
   
       20 . The method as in  claim 12 , wherein the deplating preferentially removes the copper from over the openings.