Wafer pretreatment for copper electroplating

Abstract

The present invention is directed to a pretreatment process for copper electroplating of via or trench features on a wafer, comprising filling the via or trench feature with a pretreatment solution, wherein the pretreatment solution comprises copper ions.

1 . A process for pretreating a via or trench feature on a wafer, the process comprising:
 filling a via or trench feature on a wafer with a pretreatment solution comprising copper ions,   wherein a concentration of copper in the pretreatment solution is in a range from 10 g/L to 300 g/L, and the copper concentration of the pretreatment solution is higher than a copper concentration of a copper electroplating solution.   
     
     
         2 . (canceled) 
     
     
         3 . The process of  claim 1 , wherein the pretreatment solution is essentially free of any sulfur-comprising organic compound. 
     
     
         4 . The process of  claim 3 , wherein a concentration of the copper ions is in a range from 30 g/L to 136 g/L. 
     
     
         5 . The process of  claim 1 , wherein the pretreatment solution further comprises an additive. 
     
     
         6 . The process of  claim 5 , wherein the additive is at least one selected from the group consisting of an accelerator, a suppressor, a leveler, a surfactant, and an acid. 
     
     
         7 . The process of  claim 6 , wherein a concentration of the accelerator in the pretreatment solution is in a range from 0 mL/L to about 50 mL/L. 
     
     
         8 . The process of  claim 6 , wherein a concentration of an active compound of the accelerator in the pretreatment solution is in a range from 0 ppm to 400 ppm. 
     
     
         9 . The process of  claim 6 , wherein a concentration of the suppressor in the pretreatment solution is in a range from 0 mL/L to about 40 mL/L. 
     
     
         10 . The process of  claim 6 , wherein a concentration of an active compound of the suppressor in the pretreatment solution is in a range from 0 ppm to 600 ppm. 
     
     
         11 . The process of  claim 6 , wherein a concentration of the leveler in the pretreatment solution is in a range from 0 mL/L to about 50 mL/L. 
     
     
         12 . The process of  claim 6 , wherein a concentration of an active compound of the leveler in the pretreatment solution is in a range from about 0 ppm to 500 ppm. 
     
     
         13 . The process of  claim 6 , wherein a concentration of the surfactant in the pretreatment solution is in a range from 0 wt % to about 3 wt %. 
     
     
         14 . (canceled) 
     
     
         15 . The process of  claim 6 , wherein the acid is selected from the group consisting of sulfuric acid, methanesulfonic acid, and hydrochloric acid. 
     
     
         16 . The process of  claim 6 , wherein a concentration of the acid in the pretreatment solution is from 0 mL/L to about 40 mL/L. 
     
     
         17 . The process of  claim 1 , wherein the via or trench feature has an aspect ratio greater than 2:1. 
     
     
         18 . The process of  claim 1 , wherein the via or trench feature has a depth of more than 10 micrometers. 
     
     
         19 . The process of  claim 1 , further comprising:
 rinsing a surface of the wafer with water or spin drying the wafer, to remove the pretreatment solution from the surface of the wafer.   
     
     
         20 . A process for copper electroplating a via or trench feature on a wafer, the process comprising:
 contacting a via or trench feature on a wafer obtained by the process of  claim 1  with a copper electroplating solution; and   applying a current density to the wafer for a time sufficient to deposit a copper layer onto the wafer.   
     
     
         21 . A copper electroplating pretreatment solution, comprising copper ions,
 wherein a concentration of copper in the pretreatment solution is in a range from 10 g/L to 300 g/L.   
     
     
         22 . A process for reducing electroplating voids and defects on a wafer, the process comprising:
 contacting a via or trench feature on a wafer with a solution comprising copper ions, wherein a concentration of the copper ions in the solution is in a range from 10 g/L to 300 g/L, to obtain a pretreated wafer; and then,   copper electroplating the via or trench feature with a electroplating solution comprising copper,   wherein the copper concentration of the solution is higher than a copper concentration of the electroplating solution.