Electrochemical deposition processes for semiconductor wafers

Abstract

A method for electroplating a wafer detects plating bath failure based on a voltage change. The method is useful in plating wafers having TSV features. Voltage of each anode of a plating processor may be monitored. An abrupt drop in voltage signals a bath failure resulting from conversion of an accelerator such as SPS to it's by products MPS. Bath failure is delayed or avoided by current pulsing or current ramping. An improved plating bath has a catholyte with a very low acid concentration.

1 . A method for electroplating a wafer, comprising:
 placing the wafer into contact with a bath of electrolyte having an accelerator, a leveler and a suppressor;   passing electrical current from one or more anodes through the electrolyte and through a conductive layer on the wafer;   monitoring the voltage of the one or more anodes;   detecting a failure of the bath from a change of the voltage.   
     
     
         2 . The method of  claim 1  further comprising detecting a failure of the bath on the basis of a drop in voltage of at least 100 mV. 
     
     
         3 . The method of  claim 1  wherein the wafer has TSV features. 
     
     
         4 . A method for electroplating a wafer, comprising:
 placing the wafer into contact with a bath of electrolyte having an accelerator and a suppressor;   passing electrical current from one or more anodes through the electrolyte and through a conductive layer on the wafer; and   pulsing the electrical current to control formation of MPS in the bath.   
     
     
         5 . The method of  claim 4  further including monitoring the voltage of the one or more anodes to detect a failure of the bath based on a drop or an oscillation of the voltage. 
     
     
         6 . The method of  claim 4  wherein the wafer has TSV features. 
     
     
         7 . A method for electroplating a wafer, comprising:
 placing the wafer into contact with a bath of electrolyte having an accelerator and a suppressor;   passing electrical current from one or more anodes through the electrolyte and through a conductive layer on the wafer; and   ramping the electrical current to control formation of MPS in the bath.   
     
     
         8 . The method of  claim 7  further including monitoring the voltage of the one or more anodes to detect a failure of the bath based on a drop or an oscillation of the voltage. 
     
     
         9 . The method of  claim 7  wherein the wafer has TSV features.