Method and apparatus for electroplating semiconductor wafer when controlling cations in electrolyte

Abstract

Apparatus and methods for electroplating metal onto substrates are disclosed. The electroplating apparatus comprise an electroplating cell and at least one oxidization device. The electroplating cell comprises a cathode chamber and an anode chamber separated by a porous barrier that allows metal cations to pass through but prevents organic particles from crossing. The oxidation device (ODD) is configured to oxidize cations of the metal to be electroplated onto the substrate, which cations are present in the anolyte during electroplating. In some embodiments, the ODD is implemented as a carbon anode that removes Cu(I) from the anolyte electrochemically. In other embodiments, the ODD is implemented as an oxygenation device (OGD) or an impressed current cathodic protection anode (ICCP anode), both of which increase oxygen concentration in anolyte solutions. Methods for efficient electroplating are also disclosed.

What is claimed is: 
     
         1 . An apparatus for electroplating a metal onto a substrate, the apparatus comprising:
 (a) an electroplating cell comprising:
 a cathode chamber for containing catholyte during electroplating; 
 a cathode electrical connection in the cathode chamber, the cathode electrical connection being able to connect to the substrate and apply a potential allowing the substrate to become a cathode; 
 an anode chamber for containing anolyte during electroplating; 
 an anode electrical connection in the anode chamber, the anode electrical connection being able to connect to an electroplating anode and apply a potential to the electroplating anode; and 
 a porous transport barrier placed between the anode chamber and the cathode chamber, which transport barrier enables migration of ionic species in an electrolyte, including metal cations, across the transport barrier while substantially preventing organic additives from passing across the transport barrier; and 
   (b) at least one oxidation device (ODD) configured to oxidize cations of the metal to be electroplated onto the substrate, which cations are present in the anolyte during electroplating.   
     
     
         2 . A method of electroplating a metal onto a substrate, the method comprising:
 (a) providing an anolyte in an anode chamber having an anode and being separated from a cathode chamber by a porous transport barrier that enables migration of ionic species, including metal cations, across the transport barrier while substantially blocking organic plating additives from diffusing across the transport barrier;   (b) providing a catholyte to the cathode chamber containing the substrate attached to a cathode electrical connection, wherein the catholyte contains a substantially greater concentration of the organic plating additives than the anolyte;   (c) oxidizing cations of the metal to be electroplated onto the substrate, which cations are present in the anolyte during electroplating; and   (d) applying a potential difference between the substrate and the anode, thereby plating the metal onto the substrate without substantially increasing the concentration of plating additives in the anolyte.