Plating chemistry and method of single-step electroplating of copper on a barrier metal

Abstract

Embodiments of a method of copper plating a substrate surface with a group VIII metal layer have been described. In one embodiment, a method of plating copper on a substrate surface with a group VIII metal layer comprises pre-treating the substrate surface by removing a group VIII metal surface oxide layer and/or surface contaminants and plating the substrate in a copper plating solution comprising about 50 g/l to about 300 g/l of sulfuric acid at an initial plating current higher than the critical current density to deposit a continuous copper layer on the substrate surface. The Pre-treating the substrate can be accomplished by annealing the substrate in an environment with a hydrogen-containing gas environment and/or a non-reactive gas(es) to Ru, by a cathodic treatment in an acid-containing bath, or by immersing the substrate in an acid-containing bath.

1 . A method of plating a copper layer onto a substrate surface, wherein the substrate surface comprises a group VIII metal layer, comprising: 
 pre-treating the substrate surface to remove a surface oxide layer and/or surface contaminants from the group VIII metal layer surface;    immersing the substrate surface into an acidic copper plating solution; and    applying a first electrical bias to the substrate surface after the substrate surface is immersed in the copper plating solution to assist copper nucleation on the substrate surface, the first electrical bias being configured to generate a first current density across the substrate surface greater than a critical current density.    
   
   
       2 . The method of  claim 1 , further comprising: 
 applying a second electrical bias to the substrate surface to deposit a gap-fill layer, wherein the second electrical bias is configured to generate a second current density across the substrate surface that is lower than the first current density.    
   
   
       3 . The method of  claim 1 , wherein the acidity in the acidic copper plating solution comes from sulfuric acid, whose concentration is in the range between about 50 g/l to about 300 g/l.  
   
   
       4 . The method of  claim 2 , further comprising: 
 applying a final electrical bias to the substrate surface to deposit a bulk-fill layer, wherein the final electrical bias is configured to generate a final current density across the substrate surface that is higher than the second current density.    
   
   
       5 . The method of  claim 1 , wherein the copper plating solution further comprises a copper concentration of between about 20 g/l to about 60 g/l, and a chlorine concentration of between about 20 ppm to about 100 ppm.  
   
   
       6 . The method of  claim 4 , wherein the copper plating solution further comprising adding a suppressor at a concentration of between about 100 ppm to about 1000 ppm, an accelerator at a concentration of between 2 ppm to about 30 ppm, and a leveler at a concentration of between about 1 ml/l and about 12 ml/l.  
   
   
       7 . The method of  claim 1 , wherein the copper plating solution is maintained at a temperature between 10° C. to about 30° C.  
   
   
       8 . The method of  claim 1 , wherein the substrate is rotated at between about 10 rpm and about 200 rpm while the substrate surface contacts the copper plating solution.  
   
   
       9 . The method of  claim 3 , wherein the first current density is between about 5 mA/cm 2  to about 60 mA/cm 2 .  
   
   
       10 . The method of  claim 8 , wherein the first current is applied for a duration between about 0.1 second to about 5 seconds.  
   
   
       11 . The method of  claim 2 , wherein the second current is between about 2 mA/cm 2  to about 10 mA/cm 2  and the second current is applied for a duration between about 3 seconds to about 20 seconds.  
   
   
       12 . The method of  claim 4 , wherein the final current is between about 40 mA/cm 2  to about 60 mA/cm 2  and the final current is applied for a duration between about 10 seconds to about 60 seconds.  
   
   
       13 . The method of  claim 4 , further comprises: 
 applying a third electrical bias, before applying the final electrical bias, to the substrate surface to deposit a transitional layer, wherein the third electrical bias is configured to generate a third current density across the substrate surface that is higher than the second current density and lower than the final current density.    
   
   
       14 . The method of  claim 13 , wherein the third current is between about 10 mA/cm 2  to about 30 mA/cm 2  and the third current is applied for a duration between about 0 second to about 10 seconds.  
   
   
       15 . The method of  claim 1 , wherein the group VIII metal is selected from the group of ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), and platinum (Pt).  
   
   
       16 . The method of  claim 1 , wherein the group VIII metal is ruthenium (Ru).  
   
   
       17 . The method of  claim 1 , wherein the copper plating is performed within 4 hours after the pre-treatment.  
   
   
       18 . The method of  claim 1 , wherein pre-treating the substrate surface is accomplished by annealing the substrate in an environment with a hydrogen-containing gas and/or a gas(es) non-reactive to the group VIII metal.  
   
   
       19 . The method of  claim 18 , wherein the annealing gas is a forming gas that contains about 4% hydrogen and about 96% nitrogen.  
   
   
       20 . The method of  claim 18 , wherein the annealing gas flow rate is between about 1 sccm to about 20 μm.  
   
   
       21 . The method of  claim 18 , wherein the annealing temperature is between about 100° C. to about 400° C.  
   
   
       22 . The method of  claim 18 , wherein annealing duration is between about 2 seconds to about 5 hours.  
   
   
       23  A method of plating a copper layer onto a substrate surface, wherein the substrate surface comprises a group VIII metal layer, comprising: 
 pre-treating the substrate surface to remove a surface oxide layer and/or surface contaminants from the group VIII metal layer surface;    immersing the substrate surface into an acidic copper plating solution;    applying a first electrical bias to the substrate surface after the substrate surface is immersed in the copper plating solution to assist copper nucleation on the substrate surface, the first electrical bias being configured to generate a first current density across the substrate surface greater than a critical current density; and    applying a second electrical bias to the substrate surface to deposit a gap-fill layer, wherein the second electrical bias is configured to generate a second current density across the substrate surface that is lower than the first current density.    
   
   
       24 . A method of plating copper layer onto a substrate surface, wherein the substrate surface comprises a group VIII metal layer, comprising: 
 pre-treating the substrate surface to remove surface oxide layer and/or surface contaminants from the group VIII metal layer surface;    immersing the substrate surface into a copper plating solution, wherein the copper plating solution comprises about 50 g/l to about 300 g/l of sulfuric acid; and    applying a first electrical bias to the substrate surface after the substrate surface is immersed in the copper plating solution to assist copper deposit nucleation on the substrate surface, the first electrical bias being configured to generate a first current density across the substrate surface greater than a critical current density.    
   
   
       25 . The method of  claim 24 , further comprising: 
 applying a second electrical bias to the substrate surface to deposit a gap-fill layer, wherein the second electrical bias is configured to generate a second current density across the substrate surface that is lower than the first current density.    
   
   
       26 . The method of  claim 25 , further comprises: 
 applying a final electrical bias to the substrate surface to deposit a bulk-fill layer, wherein the final electrical bias is configured to generate a final current density across the substrate surface that is higher than the second current density.    
   
   
       27 . The method of  claim 24 , wherein the copper plating solution further comprises a copper concentration of between about 20 g/l to about 60 g/l, and a chlorine concentration of between about 20 ppm to about 100 ppm.  
   
   
       28 . The method of  claim 27 , wherein the copper plating solution further comprising adding a suppressor at a concentration of between about 100 ppm to about 1000 ppm, an accelerator at a concentration of between 2 ppm to about 30 ppm, and a leveler at a concentration of between about 1 ml/l and about 12 ml/l.  
   
   
       29 . The method of  claim 24 , wherein the copper plating solution is maintained at a temperature between 10° C. to about 30° C.  
   
   
       30 . The method of  claim 24 , wherein the substrate is rotated at between about 10 rpm and about 200 rpm while the substrate surface contacts the copper plating solution.  
   
   
       31 . The method of  claim 24 , wherein the first current density is between about 5 mA/cm 2  to about 60 mA/cm 2 .  
   
   
       32 . The method of  claim 24 , wherein the first current is applied for a duration between about 0.1 second to about 5 seconds.  
   
   
       33 . The method of  claim 24 , wherein the second current is between about 2 mA/cm 2  to about 10 mA/cm 2  and the second current is applied for a duration between about 3 seconds to about 20 seconds.  
   
   
       34 . The method of  claim 25 , wherein the final current is between about 40 mA/cm 2  to about 60 mA/cm 2  and the final current is applied for a duration between about 10 seconds to about 60 seconds.  
   
   
       35 . The method of  claim 25 , further comprises: 
 applying a third electrical bias, before applying the final electrical bias, to the substrate surface to deposit a transitional layer, wherein the third electrical bias is configured to generate a third current density across the substrate surface that is higher than the second current density and lower than the final current density.    
   
   
       36 . The method of  claim 35 , wherein the third current is between about 10 mA/cm 2  to about 30 mA/cm 2  and the third current is applied for a duration between about 0 second to about 10 seconds.  
   
   
       37 . The method of  claim 24 , wherein the group VIII metal is selected from the group of ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), and platinum (Pt).  
   
   
       38 . The method of  claim 24 , wherein the group VIII metal is ruthenium (Ru).  
   
   
       39 . The method of  claim 24 , wherein the copper plating is performed within 4 hours after the pre-treatment.  
   
   
       40 . The method of  claim 24 , wherein pre-treating the substrate surface is accomplished by annealing the substrate in an environment with a hydrogen-containing gas and/or a gas(es) non-reactive to the group VIII metal.  
   
   
       41 . A method of plating copper layer onto a substrate surface, wherein the substrate surface comprises a group VIII metal layer, comprising: 
 pre-treating the substrate surface to remove surface oxide layer and/or surface contaminants from the group VIII metal layer surface;    immersing the substrate surface into a copper plating solution, wherein the copper plating solution comprises about 50 g/l to about 300 g/l of sulfuric acid;    applying a first electrical bias to the substrate surface after the substrate surface is immersed in the copper plating solution to assist copper deposit nucleation on the substrate surface, the first electrical bias being configured to generate a first current density across the substrate surface greater than a critical current density; and    applying a second electrical bias to the substrate surface to deposit a gap-fill layer, wherein the second electrical bias is configured to generate a second current density across the substrate surface that is lower than the first current density.    
   
   
       42 . A method of plating a copper layer onto a substrate surface, wherein the substrate surface comprises a group VIII metal layer, comprising: 
 pre-treating the substrate surface to remove a surface oxide layer and/or surface contaminants from the group VIII metal layer surface;    immersing the substrate surface into an acidic copper plating solution; and    applying a first electrical bias voltage to the substrate surface after the substrate surface is immersed in the copper plating solution to assist copper nucleation on the substrate surface, the first electrical bias voltage being configured to generate a current density across the substrate surface greater than a critical current density.    
   
   
       43 . A method of plating a copper layer onto a substrate surface, wherein the substrate surface comprises a group VIII metal layer, comprising: 
 pre-treating the substrate surface to remove a surface oxide layer and/or surface contaminants from the group VIII metal layer surface;    immersing the substrate surface into an acidic copper plating solution;    applying a first electrical bias voltage to the substrate surface after the substrate surface is immersed in the copper plating solution to assist copper nucleation on the substrate surface, the first electrical bias voltage being configured to generate a current density across the substrate surface greater than a critical current density; and    applying a second electrical bias voltage to the substrate surface to deposit a gap-fill layer, wherein the second electrical bias voltage is lower than the first electrical bias voltage.    
   
   
       44 . A method of plating a copper layer onto a substrate surface, wherein the substrate surface comprises a group VIII metal layer, comprising: 
 pre-treating the substrate surface to remove a surface oxide layer and/or surface contaminants from the group VIII metal layer surface;    immersing the substrate surface into a copper plating solution, wherein the copper plating solution comprises about 50 g/l to about 300 g/l of sulfuric acid; and    applying a first electrical bias voltage to the substrate surface after the substrate surface is immersed in the copper plating solution to assist copper nucleation on the substrate surface, the first electrical bias voltage being configured to generate a current density across the substrate surface greater than a critical current density.    
   
   
       45 . A method of plating a copper layer onto a substrate surface, wherein the substrate surface comprises a group VIII metal layer, comprising: 
 pre-treating the substrate surface to remove a surface oxide layer and/or surface contaminants from the group VIII metal layer surface;    immersing the substrate surface into a copper plating solution, wherein the copper plating solution comprises about 50 g/l to about 300 g/l of sulfuric acid;    applying a first electrical bias voltage to the substrate surface after the substrate surface is immersed in the copper plating solution to assist copper nucleation on the substrate surface, the first electrical bias voltage being configured to generate a current density across the substrate surface greater than a critical current density; and    applying a second electrical bias voltage to the substrate surface to deposit a gap-fill layer, wherein the second electrical bias voltage is lower than the first electrical bias voltage.    
   
   
       46 . The method of  claim 1 , wherein the first electrical bias is a bias current.  
   
   
       47 . The method of  claim 46 , wherein the first electrical bias current is pulsed.  
   
   
       48 . The method of  claim 46 , wherein the first electrical bias current is a ramp-down current.  
   
   
       49 . The method of  claim 42 , wherein the first electrical bias voltage is pulsed.  
   
   
       50 . The method of  claim 42 , wherein the electrical bias voltage is a ramp-down voltage.