Workpiece Processing Technique

Abstract

Methods for processing of a workpiece are disclosed. The actual rate at which different portions of an ion beam can process a workpiece, referred to as the processing rate profile, is determined by measuring the amount of material removed from, or added to, a workpiece by the ion beam as a function of ion beam position. An initial thickness profile of a workpiece to be processed is determined. Based on the initial thickness profile, a target thickness profile, and the processing rate profile of the ion beam, a first set of processing parameters are determined. The workpiece is then processed using this first set of processing parameters. In some embodiments, an updated thickness profile is determined after the first process and a second set of processing parameters are determined. A second process is performed using the second set of processing parameters. Optimizations to improve throughput are also disclosed.

What is claimed is: 
     
         1 . A method of processing a workpiece, comprising:
 measuring an initial thickness profile of a first workpiece;   directing an ion beam toward the first workpiece for a predetermined time or dose;   measuring an updated thickness profile of the first workpiece after the directing;   determining an etch rate profile of the ion beam as a function of ion beam position based on a difference between the initial thickness profile and the updated thickness profile; and   processing a second workpiece based on the etch rate profile of the ion beam.   
     
     
         2 . The method of  claim 1 , wherein the processing of the second workpiece is performed using a plurality of passes, wherein the ion beam is scanned across the second workpiece during each pass, wherein the etch rate profile is used to determine a first set of processing parameters that are selected from the group consisting of a number of passes, and operating parameters used during each pass. 
     
     
         3 . The method of  claim 2 , wherein the operating parameters are selected from the group consisting of a scan speed profile, a duty cycle of the ion beam, an extraction current or voltage, and a pressure of a feed gas. 
     
     
         4 . The method of  claim 1 , wherein the initial thickness profile and the updated thickness profile are measured using a reflectometer. 
     
     
         5 . The method of  claim 1 , wherein the processing comprises an etch process, a deposition process or an amorphization process. 
     
     
         6 . A method of processing a workpiece, comprising:
 determining a processing rate profile of an ion beam as a function of ion beam position;   determining an initial thickness profile of the workpiece;   using the processing rate profile, the initial thickness profile and a target thickness profile to calculate a first set of processing parameters; and   processing the workpiece using the first set of processing parameters.   
     
     
         7 . The method of  claim 6 , further comprising:
 determining an updated thickness profile of the workpiece after the processing;   using the processing rate profile, the updated thickness profile and the target thickness profile to calculate a second set of processing parameters; and   processing the workpiece using the second set of processing parameters.   
     
     
         8 . The method of  claim 6 , wherein determining the processing rate profile comprises:
 measuring an initial thickness profile of a sacrificial workpiece;   directing the ion beam toward the sacrificial workpiece for a predetermined time or dose;   measuring an updated thickness profile of the sacrificial workpiece after the directing; and   determining the processing rate profile based on a difference between the initial thickness profile and the updated thickness profile.   
     
     
         9 . The method of  claim 8 , wherein the processing rate profile is determined based on the predetermined time. 
     
     
         10 . The method of  claim 8 , wherein the ion beam removes material from the sacrificial workpiece, and the processing rate profile comprises an etch rate profile. 
     
     
         11 . The method of  claim 8 , wherein the ion beam deposits material on the sacrificial workpiece, and the processing rate profile comprises a deposition rate profile. 
     
     
         12 . The method of  claim 6 , wherein the processing is performed using a plurality of passes, wherein the ion beam is scanned across the workpiece during each pass, and wherein the first set of processing parameters is selected from the group consisting of a number of passes and operating parameters used during each pass. 
     
     
         13 . The method of  claim 12 , wherein the operating parameters are selected from the group consisting of a scan speed profile, a duty cycle of the ion beam, an extraction current or voltage, and a pressure of a feed gas. 
     
     
         14 . The method of  claim 6 , wherein the processing comprises an etch process, a deposition process or an amorphization process. 
     
     
         15 . A method of processing a plurality of workpieces from a lot, comprising:
 determining an etch rate profile of an ion beam as a function of ion beam position using a sacrificial workpiece;   determining an initial thickness profile of a first workpiece of the lot;   using the etch rate profile, the initial thickness profile of the first workpiece and a target thickness profile to calculate a first set of processing parameters;   processing the first workpiece of the lot using the first set of processing parameters; and   processing a second workpiece of the lot using the first set of processing parameters.   
     
     
         16 . The method of  claim 15 , further comprising, before processing the second workpiece:
 determining an updated thickness profile of the first workpiece of the lot after the processing of the first workpiece;   using the etch rate profile, the updated thickness profile of the first workpiece and the target thickness profile to calculate a second set of processing parameters for the first workpiece; and   processing the first workpiece of the lot using the second set of processing parameters for the first workpiece.   
     
     
         17 . The method of  claim 16 , further comprising:
 determining an updated thickness profile of the second workpiece of the lot after processing the second workpiece;   using the etch rate profile, the updated thickness profile of the second workpiece and the target thickness profile to calculate a second set of processing parameters for the second workpiece; and   processing the second workpiece of the lot using the second set of processing parameters for the second workpiece.   
     
     
         18 . The method of  claim 15 , wherein determining the etch rate profile comprises:
 measuring an initial thickness profile of the sacrificial workpiece;   directing the ion beam toward the sacrificial workpiece for a predetermined time or dose;   measuring an updated thickness profile of the sacrificial workpiece after the directing; and   determining the etch rate profile based on a difference between the initial thickness profile and the updated thickness profile.