Electrolyte loop with pressure regulation for separated anode chamber of electroplating system

Abstract

An electrolyte, and particularly anolyte, may be circulated via an open loop having a pressure regulator, so that the pressure in the plating chamber is maintained at a constant (or substantially constant) value with respect to atmospheric pressure. In these embodiments, a pressure regulator is in fluid communication with the anode chamber.

1 . An apparatus for electroplating onto substrates, comprising:
 (a) a separated anode chamber for containing electrolyte and an anode;   (b) a cathode chamber for receiving substrates and contacting them with a catholyte;   (c) a separation structure positioned therebetween, said separation structure comprising a transport barrier which enables passage of ionic species across the transport barrier while maintaining different electrolyte compositions in the anode chamber and the cathode chamber; and   (d) an open loop recirculation system for providing electrolyte to and removing electrolyte from the separated anode chamber during electroplating, wherein the open loop recirculation system is configured to expose the electrolyte to atmospheric pressure and comprises a pressure regulating device arranged to maintain the electrolyte in the anode chamber at a substantially constant pressure.   
     
     
         2 . The apparatus of  claim 1 , wherein the pressure regulating device includes a bubble separation device, for removing bubbles from the electrolyte. 
     
     
         3 . The apparatus of  claim 1 , wherein the open loop recirculation system is arranged to circulate electrolyte out of the separated anode chamber, through the pressure regulating device, and back into the separated anode chamber. 
     
     
         4 . The apparatus of  claim 3 , wherein the recirculation system further comprises a pump located outside the anode chamber and configured to draw electrolyte out of the pressure regulating device and force it into the separated anode chamber. 
     
     
         5 . The apparatus of  claim 1 , wherein the pressure regulating device comprises a vertical column arranged to serve as a conduit through which the electrolyte flows upward before spilling over a top of the vertical column, and wherein, in operation, the vertical column provides a pressure head which maintains a constant pressure in the separated anode chamber. 
     
     
         6 . The apparatus of  claim 5 , further comprising a filter fitted around the outside of the vertical column. 
     
     
         7 . The apparatus of  claim 5 , wherein the pressure regulating device further comprises (i) an outer housing for holding electrolyte that has spilled over the top of the vertical column, and (ii) an outlet port for delivering recirculating electrolyte. 
     
     
         8 . The apparatus of  claim 7 , further comprising one or more level sensors for sensing the level of electrolyte contained between the vertical column and the outer housing. 
     
     
         9 . The apparatus of  claim 8 , further comprising a controller configured to maintain the level of electrolyte within a defined height between the vertical column and the outer housing. 
     
     
         10 . The apparatus of  claim 1 , wherein, during operation, the electrolyte in the separated anode chamber is maintained at a pressure of about 0.5 and 1 psig. 
     
     
         11 . The apparatus of  claim 1 , further comprising a storage reservoir connected to the cathode chamber to provide catholyte to the cathode chamber. 
     
     
         12 . The apparatus of  claim 11 , wherein the pressure regulating device comprises an electrolyte overflow outlet for providing excess electrolyte to the storage reservoir. 
     
     
         13 . The apparatus of  claim 12 , wherein the electrolyte overflow outlet is connected to a trough. 
     
     
         14 . The apparatus of  claim 1 , wherein the pressure regulating device comprises an open-air vent. 
     
     
         15 . The apparatus of  claim 1 , wherein the open loop recirculation system further comprises an inlet for introducing additional fluid into the electrolyte. 
     
     
         16 . The apparatus of  claim 1 , further comprising a make up solution entry port for directly dosing electrolyte in the recirculation system with a make up solution. 
     
     
         17 . The apparatus of  claim 1 , further comprising a diluent entry port for directly dosing the electrolyte in the recirculation system with a diluent. 
     
     
         18 . The apparatus of  claim 1 , further comprising a controller for controlling delivery of the diluent and the make up solution to the recirculating anolyte. 
     
     
         19 . The apparatus of  claim 1 , wherein the transport barrier comprises a cation transport membrane. 
     
     
         20 . The apparatus of  claim 1 , wherein the anode chamber includes a reverse conical ceiling. 
     
     
         21 . The apparatus of  claim 1 , further comprising a second separated anode chamber that shares the open loop recirculation system with the separated anode chamber recited in  claim 1 . 
     
     
         22 . An apparatus for electroplating a metal onto a substrate, the apparatus comprising:
 separate anode and cathode chambers ionically connected to one another;   an anolyte flow loop that circulates anolyte into, out of, and through the anode chamber;   a porous transport barrier separating the anode chamber from the cathode chamber, which transport barrier enables migration of ionic species across the transport barrier while substantially preventing non-ionic organic bath additives from passing across the transport barrier; and   a pressure regulating device coupled to the anolyte flow loop and comprising a vertical column arranged to provide pressure head that maintains the anolyte in the anode chamber at a substantially constant pressure.   
     
     
         23 . The apparatus of  claim 22 , further comprising an anolyte make up subsystem that periodically delivers anolyte to the anolyte flow loop. 
     
     
         24 . The apparatus of  claim 22 , further comprising a catholyte storage reservoir connected to the cathode chamber to provide catholyte to the cathode chamber. 
     
     
         25 . The apparatus of  claim 22 , wherein the anode chamber includes a reverse conical ceiling. 
     
     
         26 . The apparatus of  claim 22 , wherein the cathode chamber includes a diffuser that causes the catholyte to flow upward in a substantially uniform manner as it contacts the substrate. 
     
     
         27 . The apparatus of  claim 22 , further comprising a stepper.