Modified electroplating solution components in a low-acid electrolyte solution

Abstract

An embodiment of the invention provides a method for reducing within die thickness variations by modifying the concentration of components of a low-acid electroplating solution. For one embodiment, the leveler concentration is increased sufficiently to reduce within die thickness variations to a specified value. For one embodiment of the invention, the leveler and suppressor are increased to reduce within die thickness variations and substantially reduce a plurality of electroplating defects. In such an embodiment the combined concentration of leveler and suppressor is determined to maintain adequate gap fill.

1 - 8 . (canceled)  
     
     
         9 . A low-acid electroplating solution comprising: 
 a sulfuric acid having a concentration of less than 175 g/l;    a conductive metal, the concentration of the conductive metal based upon the concentration of the sulfuric acid;    a leveler having a concentration based upon the concentration of the sulfuric acid and the conductive metal; and    a suppressor having a concentration based upon the concentration of the leveler.    
     
     
         10 . The low-acid electroplating solution of  claim 9  wherein the concentration of sulfuric acid is approximately 10 g/l, the conductive metal is copper and the concentration of copper is approximately 17.5 g/l, the concentration of leveler is within the range 4 ml/l-12 ml/l, and the concentration of suppressor is within the range 1 ml/l-6.0 ml/l.  
     
     
         11 . The low-acid electroplating solution of  claim 10  further comprising: 
 a chloride having a concentration within the range 50 mg/1-65 mg/l; and    an accelerator having a concentration within the range 1 ml/l-3.3 ml/l.    
     
     
         12 . The low-acid electroplating solution of  claim 11  wherein the concentration of leveler is approximately 12 ml/l, the concentration of suppressor is approximately 6 ml/l, the concentration of chloride is approximately 50 mg/l, and the concentration of accelerator is approximately 1.0 ml/l.  
     
     
         13 . The low-acid electroplating solution of  claim 12  wherein the chloride concentration and the accelerator concentration are determined based upon one or more characteristics of a substrate.  
     
     
         14 . The low-acid electroplating solution of  claim 13  wherein the one or more characteristics of the substrate include feature size and feature aspect ratio.  
     
     
         15 . An apparatus comprising: 
 a substrate having one or more features formed thereon; and    a layer of conductive metal formed on the substrate by electroplating the substrate using a low-acid electroplating solution, the low-acid electroplating solution including a leveler, a concentration of the leveler sufficient to reduce a within die thickness variation to a specified value.    
     
     
         16 . The apparatus of  claim 15  wherein the conductive metal is copper and the concentration of the leveler is within the range 4 ml/l-12 ml/l.  
     
     
         17 . The apparatus of  claim 15  wherein the substrate is silicon and the conductive metal is a metal selected from the group consisting essentially of copper, silver, gold, and alloys thereof.  
     
     
         18 . The apparatus of  claim 15  wherein at least one of the plurality of features has a sub-micron dimension and a high aspect ratio.  
     
     
         19 . The apparatus of  claim 15  wherein the low-acid electroplating solution further includes a suppressor, a concentration of the suppressor based upon the concentration of leveler, sufficient to substantially reduce a plurality of electroplating defects.  
     
     
         20 . The apparatus of  claim 19  wherein the low-acid electroplating solution includes a combined concentration of leveler and suppressor that is determined to be below a specified value.  
     
     
         21 . The apparatus of  claim 20  wherein the concentration of suppressor is within the range 1 ml/l-6 ml/l.  
     
     
         22 . The apparatus of  claim 19  wherein the plurality of electroplating defects includes protrusion defects, bare test wafer defects, and pit defects.  
     
     
         23 . The apparatus of  claim 22  wherein the low-acid electroplating solution includes a chloride, a concentration of the chloride based upon the concentration of the suppressor, and an accelerator, a concentration of the accelerator based upon the concentration of the leveler and the suppressor.  
     
     
         24 . The apparatus of  claim 22  wherein chloride concentration and the accelerator concentration are based upon a size and an aspect ratio of one or more of the features.