Method, chemistry, and apparatus for noble metal electroplating on a microelectronic workpiece

Abstract

The present invention is directed to an improved electroplating method, chemistry, and production worthy apparatus for depositing noble metals (e.g., platinum) and their alloys onto the surface of the workpiece, such as a semiconductor wafer, pursuant to manufacturing a microelectronic device, circuit, and/or component. The reliability of the noble metal material deposited using the disclosed method, chemistry, and/or apparatus is significantly better than the reliability of noble metal structures deposited using the teachings of the prior art. This is largely attributable to the low stress of films that are deposited using the teachings disclosed herein. The metals, which can be deposited, include gold, silver, platinum, palladium, ruthenium, iridium, rhodium, osmium and alloys containing these metals.

1 . In a method for electroplating a noble metal into submicron features on a surface of a microelectronic workpiece, wherein the surface of the workpiece to be plated is brought into contact with an electroplating solution including ions and/or complexes of the noble metal and an electroplating power is applied between the surface of the workpiece and an anode spaced from the surface of the workpiece and in contact with the electroplating solution, the improvement comprising: 
 reducing film stress within the electroplated noble metal by applying electroplating power between the surface of the workpiece and the anode using a low current for a first predetermined period of time and applying higher current electroplating power between the surface of the workpiece and the anode for a second predetermined period of time, the noble metal being deposited into the submicron features during the first and second time periods.    
     
     
         2 . The method of  claim 1 , wherein the low current is applied using a pulsed waveform.  
     
     
         3 . The method of  claim 1 , wherein the higher current electroplating power has a current density between about 3 and 9 mA/cm 2 . [ALKALINE PLATING CONDITIONS] 
     
     
         4 . The method of  claim 1 , wherein the higher current electroplating power has a current density between about 20 and 50 mA/cm 2 . [ACIDIC PLATING CONDITIONS] 
     
     
         5 . The method of  claim 4 , wherein the higher current electroplating power is applied using a pulsed waveform.  
     
     
         6 . The method of  claim 5 , wherein the pulsed waveform comprises an on-time in a range of about 1-10 milliseconds and an off-time in a range of about 1-10 milliseconds.  
     
     
         7 . The method of  claim 1 , wherein the higher current electroplating power is initiated immediately after the first predetermined period of time.