Methods and systems for controlling critical dimensions in track lithography tools

Abstract

A method of controlling wafer critical dimension (CD) uniformity on a track lithography tool includes obtaining a CD map for a wafer. The CD map includes a plurality of CD data points correlated with a multi-zone heater geometry map. The multi-zone heater includes a plurality of heater zones. The method also includes determining a CD value for a first heater zone of the plurality of heater zones based on one or more of the CD data points and computing a difference between the determined CD value for the first heater zone and a target CD value for the first heater zone. The method further includes determining a temperature variation for the first heater zone based, in part, on the computed difference and a temperature sensitivity of a photoresist deposited on the wafer and modifying a temperature of the first heater zone based, in part, on the temperature variation.

1 . A method of controlling wafer critical dimension (CD) uniformity on a track lithography tool, the method comprising:
 obtaining a CD map for a wafer, the CD map comprising a plurality of CD data points correlated with a multi-zone heater geometry map, wherein the multi-zone heater comprises a plurality of heater zones;   determining a CD value for a first heater zone of the plurality of heater zones based on one or more of the CD data points;   computing a difference between the determined CD value for the first heater zone and a target CD value for the first heater zone;   determining a temperature variation for the first heater zone based, in part, on the computed difference and a temperature sensitivity of a photoresist deposited on the wafer;   modifying a temperature of the first heater zone based, in part, on the temperature variation.   
   
   
       2 . The method of  claim 1  further comprising repeating the obtaining, determining a CD value, computing, determining a temperature variation, and modifying steps one or more times. 
   
   
       3 . The method of  claim 2  wherein repeating modifies a measured wafer CD to obtain a wafer CD within a predetermined value of a target wafer CD. 
   
   
       4 . The method of  claim 1  wherein the CD map for the wafer is obtained using an OCD metrology tool. 
   
   
       5 . The method of  claim 1  wherein the plurality of CD data points comprises a number of CD data points greater than or equal to the plurality of heater zones. 
   
   
       6 . The method of  claim 5  wherein the number of CD data points is greater than or equal to 29. 
   
   
       7 . The method of  claim 6  wherein the number of CD data points is greater than or equal to 66. 
   
   
       8 . The method of  claim 1  wherein the temperature sensitivity is associated with a functional relationship between CD and temperature. 
   
   
       9 . The method of  claim 1  wherein determining the CD value comprises averaging CD data points overlying the first heater zone. 
   
   
       10 . The method of  claim 1  wherein determining the CD value comprises computing a weighted average including a first set of CD data points overlying the first heater zone and a second set of CD data points not overlying the first heater zone. 
   
   
       11 . A method of controlling CD during processing of semiconductor wafers, the method comprising:
 measuring a CD profile for a first semiconductor wafer;   comparing the measured CD profile with a target CD profile;   determining that the measured CD profile is not within a predetermined tolerance of the target CD profile;   calculating a temperature offset for a zone of a multi-zone bake plate based on the determining step;   modifying a temperature set point of the zone of the multi-zone bake plate; and   processing a second semiconductor wafer using the modified temperature set point.   
   
   
       12 . The method of  claim 11  further comprising:
 calculating a second temperature offset for a second zone of the multi-zone bake plate based on the determining step; and   modifying a second temperature set point of the second zone of the multi-zone bake plate.   
   
   
       13 . The method of  claim 11  wherein the CD profile is obtained using at least one of an OCD or a CD-SEM metrology tool. 
   
   
       14 . The method of  claim 11  wherein the CD profile comprises a number of CD data points greater than or equal to a number of heater zones of the multi-zone bake plate. 
   
   
       15 . The method of  claim 11  wherein determining that the measured CD profile is not within a predetermined tolerance of the target CD profile comprises computing a weighted average including a first set of CD data points overlying the zone and a second set of CD data points not overlying the zone. 
   
   
       16 . A track lithography tool comprising:
 a factory interface configured to receive a wafer;   a process module coupled to the factory interface, the process module comprising:
 a plurality of coat stations; 
 a plurality of develop stations; and 
 a thermal treatment unit including a multi-zone bake plate including a plurality of heater zones and characterized by a multi-zone bake plate geometry map; and 
   a controller configured to receive a CD map for the wafer, the CD map comprising a plurality of CD data points correlated with the multi-zone bake plate geometry map, the controller including a computer-readable medium storing a plurality of instructions for controlling a data processor to modify a wafer CD profile, the plurality of instructions comprising:   instructions that cause the data processor to determine a CD value for a first heater zone of the plurality of heater zones based on one or more of the CD data points;   instructions that cause the data processor to compute a difference between the determined CD value for the first heater zone and a target CD value for the first heater zone;   instructions that cause the data processor to determine a temperature variation for the first heater zone based, in part, on the computed difference and a temperature sensitivity of a photoresist deposited on the wafer; and   instructions that cause the data processor to modify a temperature of the first heater zone based, in part, on the temperature variation.   
   
   
       17 . The track lithography tool of  claim 16  wherein the CD map for the wafer is obtained using a metrology tool integrated in the track lithography tool. 
   
   
       18 . The track lithography tool of  claim 16  wherein the CD map for the wafer comprises a number of CD data points greater than or equal to a number of heater zones of the multi-zone bake plate. 
   
   
       19 . The track lithography tool of  claim 16  wherein the determined CD value for the first heater zone is determined by computing a weighted average including a first set of CD data points overlying the first heater zone and a second set of CD data points not overlying the first heater zone. 
   
   
       20 . The track lithography tool of  claim 19  wherein the second set of CD data points overly a boundary region adjacent the first heater zone.