Pre-treatment to eliminate the defects formed during electrochemical plating

Abstract

Embodiments of the invention provide methods for reducing formation of void-type defects on the surface of a substrate during electrochemical plating. Embodiments of the invention provide methods to improve the wetting of a substrate surface prior to immersion and thereby minimize adhesion of bubbles to the substrate surface during immersion. A thin uniform metal oxide is formed on a metal layer on the substrate immediately prior to substrate immersion. In one aspect, exposing the substrate to an oxygen-containing gas, e.g. air, forms the metal oxide. The oxygen-containing gas may be flowed over the substrate or the substrate may be rotated at a high rate in the presence of an oxygen-containing gas. In another aspect, non-uniform metal oxides are first removed from the substrate in an anneal process and a thin uniform metal oxide is subsequently re-formed. An optimized substrate immersion method may also be used to further reduce void defects.

1 . A method for forming a layer on an electronic device substrate, comprising: 
 depositing a first metal layer on a substrate;    forming a metal oxide layer on the first metal layer by flowing an oxygen-containing gas across the first metal layer at a velocity between about 3 m/sec and about 10 m/s; and    plating a second metal layer on the metal oxide layer.    
   
   
       2 . The method of  claim 1 , wherein the oxygen-containing gas comprises atmospheric air.  
   
   
       3 . The method of  claim 1 , wherein the humidity of the oxygen-containing is between about 50% and about 70%.  
   
   
       4 . The method of  claim 1 , wherein the first metal layer is a copper-containing layer.  
   
   
       5 . The method of  claim 1 , wherein the metal oxide layer formed on the first metal layer is between about 10 Å and about 20 Å thick.  
   
   
       6 . The method of  claim 1 , wherein the substrate may include a material selected from the group consisting of monocrystalline silicon, polycrystalline silicon, amorphous silicon, strained silicon, silicon on insulator, doped silicon, silicon germanium, germanium, gallium arsenide, glass, sapphire, silicon oxide, silicon nitride, silicon oxynitride and/or carbon doped silicon oxide.  
   
   
       7 . The method of  claim 1 , further comprising: 
 immersing the first metal layer into a plating solution using an optimized tilt method, wherein the optimized tilt method comprises: 
 positioning the substrate at a first tilt angle from horizontal above the plating solution;  
 vertically displacing the substrate to immerse the first metal layer into the plating solution while maintaining the substrate at the first tilt angle from horizontal; and  
 positioning the substrate substantially parallel to an anode prior to plating.  
   
   
   
       8 . The method of  claim 7 , wherein the optimized tilt method further comprises rotating the substrate during the immersing the first metal layer step.  
   
   
       9 . The method of  claim 7 , wherein the optimized tilt method further comprises altering the position of the substrate from the first tilt angle from horizontal toward horizontal during said vertical displacing.  
   
   
       10 . The method of  claim 7 , wherein the optimized tilt method further comprises altering the position of the substrate to a second tilt angle measured from horizontal when the substrate contacts the plating solution.  
   
   
       11 . A method for forming a layer on an electronic device substrate, comprising: 
 depositing a first metal layer on a substrate;    forming a metal oxide layer on the first metal layer by rotating the substrate from about 500 rpm to about 2000 rpm in the presence of an oxygen-containing gas; and    plating a second metal layer on the metal oxide layer.    
   
   
       12 . The method of  claim 11 , wherein the oxygen-containing gas comprises atmospheric air.  
   
   
       13 . The method of  claim 11 , wherein the humidity of the oxygen-containing is between about 50% and about 70%.  
   
   
       14 . The method of  claim 11 , wherein the first metal layer is a copper-containing layer.  
   
   
       15 . The method of  claim 11 , wherein the metal oxide layer formed on the first metal layer is between about 10 Å and about 20 Å thick.  
   
   
       16 . The method of  claim 11 , wherein the substrate may include a material selected from the group consisting of monocrystalline silicon, polycrystalline silicon, amorphous silicon, strained silicon, silicon on insulator, doped silicon, silicon germanium, germanium, gallium arsenide, glass, sapphire, silicon oxide, silicon nitride, silicon oxynitride and/or carbon doped silicon oxide.  
   
   
       17 . The method of  claim 11 , further comprising: 
 immersing the first metal layer into a plating solution using an optimized tilt method, wherein the optimized tilt method comprises: 
 positioning the substrate at a first tilt angle from horizontal above the plating solution;  
 vertically displacing the substrate to immerse the metal layer into the plating solution while maintaining the substrate at the first tilt angle from horizontal; and  
 positioning the substrate substantially parallel to an anode prior to plating.  
   
   
   
       18 . The method of  claim 17 , wherein the optimized tilt method further comprises rotating the substrate during the immersing the first metal layer step.  
   
   
       19 . The method of  claim 17 , wherein the optimized tilt method further comprises altering the position of the substrate from the first tilt angle from horizontal toward horizontal during said vertical displacing.  
   
   
       20 . The method of  claim 17 , wherein the optimized tilt method further comprises altering the position of the substrate to a second tilt angle measured from horizontal when the substrate contacts the plating solution.  
   
   
       21 . A method for improving the wettability of a substrate with a metal surface layer, comprising: 
 exposing the metal surface layer of the substrate to an oxygen-containing gas until a metal oxide layer that is between about 10 Å and about 20 Å thick is formed on the metal surface layer of the substrate.    
   
   
       22 . The method of  claim 21 , wherein the process of exposing the metal surface layer of the substrate to an oxygen-containing gas comprises exposing the metal surface layer of the substrate to atmospheric air for longer than about 80 minutes and less than about 24 hours.  
   
   
       23 . The method of  claim 22 , wherein the metal surface layer is a copper-containing surface layer.  
   
   
       24 . The method of  claim 21 , wherein the process of exposing the metal surface layer of the substrate to an oxygen-containing gas comprises flowing an oxygen-containing gas over the metal surface layer of the substrate at a velocity of between about 3 m/sec and about 10 m/s.  
   
   
       25 . The method of  claim 24 , wherein the oxygen-containing gas is atmospheric air.  
   
   
       26 . The method of  claim 24 , wherein the metal surface layer is a copper-containing surface layer.  
   
   
       27 . The method of  claim 21 , wherein the process of exposing the metal surface layer of the substrate to an oxygen-containing gas comprises rotating the substrate from about 500 rpm to about 2000 rpm in the presence of an oxygen-containing gas.  
   
   
       28 . The method of  claim 27 , wherein the oxygen-containing gas is atmospheric air.  
   
   
       29 . The method of  claim 27 , wherein the metal surface layer is a copper-containing surface layer.  
   
   
       30 . The method of  claim 27 , wherein the humidity of the oxygen-containing gas is between about 50% and about 70%.  
   
   
       31 . A method of processing a substrate that has a metal layer formed thereon, comprising: 
 positioning the substrate in a first process chamber;    causing an oxygen-containing gas to flow across the substrate until a metal oxide layer about 10 to about 20 Å thick is formed on the metal layer;    immersing the substrate in a plating solution; and    plating a second metal layer on the substrate.    
   
   
       32 . The method of  claim 31 , wherein the process of causing an oxygen-containing gas to flow across the substrate comprises flowing an oxygen-containing gas over the metal surface layer of the substrate at a velocity between about 3 m/sec and about 10 m/s.  
   
   
       33 . The method of  claim 31 , wherein positioning the substrate comprises positioning the substrate on a rotatable substrate support and causing an oxygen-containing gas to flow across the substrate comprises rotating the substrate from about 500 rpm to about 2000 rpm in the presence of an oxygen-containing gas.  
   
   
       34 . The method of  claim 31 , wherein the metal layer is a copper-containing layer.  
   
   
       35 . The method of  claim 31 , wherein the oxygen-containing gas is ambient air.  
   
   
       36 . The method of  claim 31 , wherein the process of immersing the substrate in a plating solution comprises: 
 positioning the substrate at a first tilt angle above a plating solution positioned in a process chamber;    vertically displacing the substrate to immerse the metal layer into the plating solution while maintaining the substrate at the first tilt angle; and    positioning the substrate substantially parallel to an anode positioned in the plating solution prior to plating.    
   
   
       37 . The method of  claim 36 , further comprising rotating the substrate during immersion.  
   
   
       38 . The method of  claim 36 , further comprising altering the position of the substrate from the first tilt angle toward horizontal during said vertical displacing.  
   
   
       39 . The method of  claim 36 , further comprising altering the position of the substrate to a second tilt angle when the substrate contacts the plating solution.  
   
   
       40 . The method of  claim 31 , further comprising positioning the substrate in a second process chamber prior to the immersing the substrate in a plating solution step, wherein the second process chamber is adapted to perform the immersing the substrate in a plating solution step and the plating a second metal layer on the substrate step.  
   
   
       41 . The method of  claim 31 , wherein causing an oxygen-containing gas to flow across the substrate further comprises: 
 holding the substrate in a low-oxygen, hydrogen-enriched environment;    increasing the temperature of the substrate to between about 50° C. and about 100° C.; and    exposing the substrate to an oxygen-containing gas.    
   
   
       42 . A method for forming a layer on an electronic device substrate, comprising: 
 depositing a first metal layer on a substrate;    forming a metal oxide layer between about 10 Å and about 20 Å thick on the metal layer by exposing the metal layer to an oxygen-containing gas for longer than about 80 minutes and less than about 24 hours; and    plating a second metal layer on the metal oxide layer.