System and process to control electroplating a metal onto a substrate

Abstract

An electroplating system is provided with a rotatable head assembly including a substrate holder to secure a substrate for entry into a bath of electrolyte; and a head tilt mechanism including a stepper motor connected to the rotatable head assembly and configured to control bath entry parameters for optimal surface wetting of the substrate, upon bath entry for electroplating the substrate free of electroplating defects, including, but not limited to, swirl defects.

What is claimed is:  
     
         1 . An electroplating system comprising: 
 a rotatable head assembly including a substrate holder to secure a substrate for entry into an electroplating bath of electrolyte; and    a head tilt mechanism including a stepper motor connected to the rotatable head assembly and configured to control bath entry parameters for optimal surface wetting of the substrate, upon bath entry for electroplating.    
     
     
         2 . The electroplating system as claimed in  claim 1 , wherein the head tilt mechanism is automated to control the bath entry parameters, including velocity and acceleration, so as to eliminate variations in the bath entry parameters and to reduce the time required to set-up the bath entry parameters for optimal surface wetting of the substrate during an electroplating process.  
     
     
         3 . The electroplating system as claimed in  claim 1 , wherein the bath entry parameters include a substrate rotation RPM, a height above the bath prior to entry, an angle of entry into the bath, and a time taken for bath entry.  
     
     
         4 . The electroplating system as claimed in  claim 2 , further comprising a system controller configured to control, when a head tilt control program is executed, the stepper motor which controls the bath entry parameters and each step of the bath entry process during the electroplating process so as to make the bath entry process repeatable and the substrate free of electroplating defects, including, but not limited to, swirl defects.  
     
     
         5 . The electroplating system as claimed in  claim 3 , wherein the head tilt mechanism comprises: 
 a mounting post mounted onto a mainframe to provide rotational movement about a substantially vertical axis that extends through the mounting post so as to align the rotatable head assembly with an electrolyte cell containing electrolyte;    a post cover to cover a top portion of the mounting post;    a cantilever arm pivotally connected to the stepper motor and the rotatable head assembly to control entry of the rotatable head assembly into the electrolyte cell for the electroplating bath; and    a pivot joint rotatably mounted to the post cover such that the cantilever arm pivots about the post cover at the pivot joint.    
     
     
         6 . The electroplating system as claimed in  claim 4 , wherein the system controller is configured to send an instruction to a stepper motor controller, via device net protocol, which converts the instruction to pulses for the stepper motor to control the velocity and acceleration of the movement of the substrate secured by the substrate holder into the electroplating bath.  
     
     
         7 . The electroplating system as claimed in  claim 4 , wherein the system controller is configured to verify if the substrate secured by the substrate holder has reached a requested position by checking an internal home flag sensor, while monitoring velocity and acceleration parameters during the actual movement to ensure the bath entry parameters are within an acceptable tolerance band.  
     
     
         8 . The electroplating system as claimed in  claim 7 , wherein the system controller is further configured to issue a tool fault alert to alert a user to adjust the bath entry parameters, when any one of the bath entry parameters is outside of the acceptable tolerance band.  
     
     
         9 . A method for electroplating a substrate in an electroplating system including a stepper motor and a system controller, comprising: 
 moving a substrate, using said stepper motor, in position for entry into an electroplating bath of electrolyte; and    controlling bath entry parameters for optimal surface wetting of the substrate, using said system controller, when the substrate is moved into the electroplating bath for electroplating.    
     
     
         10 . The method as claimed in  claim 9 , wherein the bath entry parameters includes velocity and acceleration information, a substrate rotation RPM, a height above the bath prior to entry, an angle of entry into the bath, and a time taken for bath entry.  
     
     
         11 . The method as claimed in  claim 10 , wherein the system controller is configured to control, when a head tilt control program is executed, the stepper motor which controls the bath entry parameters and each step of the bath entry process during an electroplating process so as to make the bath entry process repeatable and the substrate free of electroplating defects, including, but not limited to, swirl defects.  
     
     
         12 . The method as claimed in  claim 9 , wherein the system controller is configured to send an instruction to a stepper motor controller, via device net protocol, which converts the instruction to pulses for the stepper motor to control the velocity and acceleration of the movement of the substrate into the electroplating bath.  
     
     
         13 . The method as claimed in  claim 12 , wherein the system controller is configured to verify if the substrate has reached a requested position by checking an internal home flag sensor, while monitoring velocity and acceleration parameters during the actual movement to ensure the bath entry parameters are within an acceptable tolerance band.  
     
     
         14 . The method as claimed in  claim 13 , wherein the system controller is further configured to issue a tool fault alert to alert a user to adjust the bath entry parameters, when any one of the bath entry parameters is outside of the acceptable tolerance band.  
     
     
         15 . Am electroplating system comprising: 
 a rotatable head assembly including a substrate holder to secure a substrate and a stepper motor to control movement of the substrate, for entry into an electroplating bath of electrolyte for electroplating; and    a head tilt mechanism including a stepper motor connected to the rotatable head assembly, configured to control bath entry parameters, including tilting the substrate at a predetermined angle for optimal surface wetting of the substrate, when the substrate is moved into the electroplating bath of electrolyte for electroplating.    
     
     
         16 . The electroplating system as claimed in  claim 15 , wherein the head tilt mechanism is automated by software to control the bath entry parameters, including velocity and acceleration, so as to eliminate variations in the bath entry parameters and to reduce the time required to set-up the bath entry parameters for optimal surface wetting of the substrate during an electroplating process.  
     
     
         17 . The electroplating system as claimed in  claim 15 , wherein the bath entry parameters include a substrate rotation RPM, a height above the bath prior to entry, an angle of entry into the bath, and a time taken for bath entry.  
     
     
         18 . The electroplating system as claimed in  claim 15 , further comprising a system controller configured to control, when a head tilt control program is executed, the stepper motor in the rotatable head assembly which control rotational movement of the substrate, and the stepper motor in the head tilt mechanism which controls the bath entry parameters and each step of the bath entry process during the electroplating process so as to make the bath entry process repeatable and the substrate free of electroplating defects, including, but not limited to, swirl defects.  
     
     
         19 . The electroplating system as claimed in  claim 15 , wherein the head tilt mechanism comprises: 
 a mounting post mounted onto a mainframe to provide rotational movement about a substantially vertical axis that extends through the mounting post so as to align the rotatable head assembly with an electrolyte cell containing electrolyte;    a post cover to cover a top portion of the mounting post;    a cantilever arm pivotally connected to the stepper motor and the rotatable head assembly to control entry of the rotatable head assembly into the electrolyte cell for the electroplating bath; and    a pivot joint rotatably mounted to the post cover such that the cantilever arm pivots about the post cover at the pivot joint.    
     
     
         20 . The electroplating system as claimed in  claim 18 , wherein the system controller is configured to send an instruction to a stepper motor controller, via device net protocol, which converts the instruction to pulses for the stepper motor to control the velocity and acceleration of the movement of the substrate secured by the substrate holder into the electroplating bath.  
     
     
         21 . The electroplating system as claimed in  claim 20 , wherein the system controller is configured to verify if the substrate secured by the substrate holder has reached a requested position by checking an internal home flag sensor, while monitoring velocity and acceleration parameters during the actual movement to ensure the bath entry parameters are within an acceptable tolerance band.  
     
     
         22 . The electroplating system as claimed in  claim 21 , wherein the system controller is further configured to issue a tool fault alert to alert a user to adjust the bath entry parameters, when any one of the bath entry parameters is outside of the acceptable tolerance band.