Method and apparatus for supplying electricity uniformly to a workpiece

Abstract

The present invention relates to a device that supplies electricity to a substrate. In one embodiment, the device includes multiple contacts, a current sensor, and a current regulator. The current sensor is attached to each of the plurality of contacts to sense their electric current. A current regulator controls current applied to each of the multiple contacts in response to the current sensor. In another embodiment, a compliant ridge is formed about the periphery of each contact to seal the contact from undesired chemicals.

What is claimed is:  
     
         1 . An apparatus for supplying electricity to a substrate, comprising: 
 a plurality of contacts;    a current sensor attached to each of the plurality of contacts; and    a current regulator that controls current applied to each of the plurality of contacts in response to the current sensor.    
     
     
         2 . The apparatus of  claim 1 , further comprising a controller that determines non-uniformity of current between each of the plurality of contacts.  
     
     
         3 . The apparatus of  claim 2 , wherein the current regulator operates in response to the controller.  
     
     
         4 . The apparatus of  claim 1 , wherein the current regulator ensures that a similar current level is applied to each of the plurality of contacts.  
     
     
         5 . The apparatus of  claim 1 , further comprising a power supply that supplies the current to each contact.  
     
     
         6 . The apparatus of  claim 5 , further comprising a plurality of individual conductors, at least one of the individual conductors connected from the power supply to each of the plurality of contacts.  
     
     
         7 . The apparatus of  claim 6 , wherein the current regulator further comprises a plurality of varistors, at least one of the varistors connected to each of the individual conductors to control current applied to each of the plurality of contacts.  
     
     
         8 . The apparatus of  claim 6 , wherein the current regulator further comprises a current control device that regulates the current over each of the individual conductors.  
     
     
         9 . The apparatus of  claim 1 , further comprising a conformal ridge formed around the periphery of the contacts.  
     
     
         10 . An method for supplying electricity to a substrate, comprising: 
 providing a plurality of contacts;    sensing the current applied to each of the plurality of contacts; and    controlling the current applied to each of the plurality of contacts in response to the current sensor.    
     
     
         11 . The method of  claim 10 , wherein controlling the current further comprises balancing the current applied to each of the plurality of contacts.  
     
     
         12 . The method of  claim 10 , wherein controlling the current further comprises varying the resistance of a conductor that supplies the current to the contact.  
     
     
         13 . The method of  claim 10 , wherein controlling the current further comprises varying the current level applied to a conductor that supplies the current to the contact.  
     
     
         14 . A method of forming a contact ring, comprising: 
 providing a substrate;    depositing at least one conductive layer on the substrate; and    depositing at least one insulative layer adjacent to the at least one conductive layer, on the substrate.    
     
     
         15 . The method of  claim 14 , further comprising electrically connecting a contact to at least one of the conductive layers.  
     
     
         16 . The method of  claim 14 , wherein at least one of the conductive layers is of sufficient thickness such that after the depositing of at least one insulative layer, a compliant ridge is defined in the insulative layer.  
     
     
         17 . The method of  claim 16 , further comprising electrically connecting a contact to at least one of the conductive layers, wherein the compliant ridge extends around the periphery of the contact.  
     
     
         18 . A contact ring for providing electrical contact between a wafer and a power supply, comprising: 
 a conductive layer    an insulative layer deposited above the conductive layer;    a contact in electrical contact with the conductive layer and extending through the insulative layer to an external surface; and    a compliant ridge formed on the external surface, and extending about the periphery of the contact.    
     
     
         19 . The contact ring of  claim 18 , wherein the insulative layer is a conformal layer, and the conductive layer is of a sufficient dimension to form the compliant ridge on the insulative layer.  
     
     
         20 . The contact ridge of  claim 18 , wherein the compliant ridge is formed by an additional layer deposited on top of the insulative layer.  
     
     
         21 . An apparatus for supplying electricity to a substrate, comprising: 
 a metal deposition system comprising a deposition cell, an anode, and a cathode, the cathode comprising: 
 a plurality of contacts,  
 a current sensor attached to each of the plurality of contacts, and  
 a current regulator that controls current applied to each of the plurality of contacts in response to the current sensor.  
   
     
     
         22 . The apparatus of  claim 21 , wherein the metal deposition system is an electroplating device.  
     
     
         23 . The apparatus of  claim 21 , further comprising a compliant ridge formed on the external surface and extending about the periphery of the contact.