Method of electroplating copper over a patterned dielectric layer

Abstract

In a new method of electroplating metal onto a patterned dielectric layer including small diameter vias and large diameter trenches, a pulse reverse electroplating sequence with a two-component chemistry is modified to substantially fill the vias, while in a subsequent DC deposition the bulk material is deposited to completely fill the large diameter trenches. Thus, good control quality compared to conventional three-component chemistry electroplating is obtained while the superior characteristics of a metal layer deposited by a two-component chemistry are preserved. The method is particularly advantageous in electroplating copper.

What is claimed:  
     
         1 . A method of depositing a metal over a substrate including a patterned dielectric layer with a small diameter opening and a large diameter opening by electroplating, the method comprising: 
 providing an electrolyte bath including a suppressor additive and an accelerator additive;    positioning the substrate in said electrolyte bath;    generating a plurality of forward current pulses, each with a first time period, and a plurality of reverse current pulses, each with a second time period, in said electrolyte bath to deposit metal on said substrate, wherein said forward current pulses and said reverse current pulses are provided in an alternating fashion; and    generating a DC current for a predefined third time period in said electrolyte bath to deposit metal on said substrate, wherein the first and second time periods are less than the third time period.    
     
     
         2 . The method of  claim 1 , wherein at least one of a height of the forward current pulse, a height of the reverse current pulse, the first time period, the second time period and a time interval for applying the current pulses and the reverse current pulses is selected to completely fill at least the small diameter opening.  
     
     
         3 . The method of  claim 1 , wherein at least one of a height of the DC current and the third time period is controlled to adjust the final thickness of the metal layer deposited on and in the patterned dielectric layer.  
     
     
         4 . The method of  claim 1 , wherein said forward current pulses and said reverse current pulses are applied for a predefined time interval and a ratio of said time interval and said third time period is controlled to adjust a quality of said metal layer.  
     
     
         5 . The method of  claim 1 , further comprising annealing said substrate to adjust a grain size in said metal layer.  
     
     
         6 . The method of  claim 1 , wherein said electrolyte bath includes copper ions.  
     
     
         7 . A method of electroplating a metal over a substrate including a surface portion with a patterned dielectric layer including a small diameter opening and a large diameter opening, the method comprising: 
 providing an electrolyte bath including a two-component additive chemistry for non-conformal filling in said small diameter opening;    positioning the substrate in the electrolyte bath;    performing a pulse reverse plating sequence to substantially fill the small diameter opening; and    applying a DC current of a predefined height for a predefined time period to completely fill the large diameter opening.    
     
     
         8 . The method of  claim 7 , wherein a time period of the pulse reverse plating sequence is controlled to adjust a surface quality of the final metal layer.  
     
     
         9 . The method of  claim 7 , wherein at least one of said predefined height and said predefined time period of the DC current is selected to adjust a surface quality of the final metal layer.  
     
     
         10 . The method of  claim 7 , wherein a height and a duration of forward current pulses and reverse current pulses in said pulse reverse plating sequence is selected to substantially completely fill the small diameter opening.  
     
     
         11 . The method of  claim 7 , wherein at least one of a height and a duration of forward current pulses and reverse current pulses in said pulse reverse plating sequence, a time period of said pulse reverse plating sequence, the predefined height of said DC current, and the predefined time period of the DC current is controlled to adjust a surface quality of the final metal layer.  
     
     
         12 . The method of  claim 7 , wherein said metal comprises copper.  
     
     
         13 . The method of  claim 7 , further comprising annealing said substrate to adjust a grain size in said metal layer.