Charged particle beam deflection method with separate stage tracking and stage positional error signals

Abstract

The invention provides a method for patterning a resist coated substrate carried on a stage, where the patterning utilizes a charged particle beam. The method comprises the steps of: moving the stage at a nominally constant velocity in a first direction; while the stage is moving, deflecting the charged particle beam in the first direction to compensate for the movement of the stage, the deflecting including: (a) compensating for an average velocity of the stage; and (b) separately compensating for the difference between an instantaneous position of the stage and a calculated position based on the average velocity. The separately compensating step uses a bandwidth of less than 10 MHz. The invention also provides a deflector control circuit for implementing the separate compensation functions.

What is claimed is: 
     
         1 . A method for patterning a resist coated substrate carried on a stage, said patterning utilizing a charged particle beam generated by a column positioned above said substrate, comprising the steps of:
 moving said stage at a nominally constant velocity in a first direction;   while said stage is moving, deflecting said charged particle beam in said first direction to compensate for the movement of said stage, said deflecting including:
 compensating for an average velocity of said stage; and 
 separately compensating for the difference between an instantaneous position of said stage and a calculated position based on said average velocity. 
   
     
     
         2 . A method as in  claim 1 , wherein said separately compensating step has a bandwidth of less than 10 MHz. 
     
     
         3 . A method as in  claim 1 , wherein said separately compensating step has a bandwidth of 1 MHz. 
     
     
         4 . A method as in  claim 1 , wherein said instantaneous position of said stage is measured using a laser interferometer system. 
     
     
         5 . A method as in  claim 1 , wherein said compensating step includes deflecting said charged particle beam with a mainfield deflector and wherein said separately compensating step includes deflecting said charged particle beam with a sub-field deflector. 
     
     
         6 . A deflector control circuit for charged particle beam deflection in a lithography system, said lithography system including a stage for moving a resist coated substrate, comprising:
 a ramp signal generator electrically connected to the charged particle beam deflector, said ramp signal generator being configured to deflect said beam to compensate for an average velocity of said stage; and   a deflection signal generator electrically connected to the charged particle beam deflector, said deflection signal generator being configured to deflect said beam to compensate for the difference between an instantaneous position of said stage and a calculated position based on said average velocity.   
     
     
         7 . A deflector control circuit as in  claim 6  wherein said deflection signal generator has a bandwidth of less than 10 MHz. 
     
     
         8 . A deflector control circuit as in  claim 6  wherein said deflection signal generator has a bandwidth of 1 MHz. 
     
     
         9 . A deflector control circuit as in  claim 6 , wherein said instantaneous position of said stage is measured using a laser interferometer system. 
     
     
         10 . A deflector control circuit as in  claim 6 , wherein said charged particle deflector comprises a mainfield deflector and a sub-field deflector and wherein said ramp signal generator is electrically connected to said mainfield deflector and said deflection signal generator is electrically connected to said sub-field deflector.