Method and System for Providing a Quality Metric for Improved Process Control

Abstract

The present invention may include acquiring a plurality of overlay metrology measurement signals from a plurality of metrology targets distributed across one or more fields of a wafer of a lot of wafers, determining a plurality of overlay estimates for each of the plurality of overlay metrology measurement signals using a plurality of overlay algorithms, generating a plurality of overlay estimate distributions, and generating a first plurality of quality metrics utilizing the generated plurality of overlay estimate distributions, wherein each quality metric corresponds with one overlay estimate distribution of the generated plurality of overlay estimate distributions, each quality metric a function of a width of a corresponding generated overlay estimate distribution, each quality metric further being a function of asymmetry present in an overlay metrology measurement signal from an associated metrology target.

What is claimed: 
     
         1 . A computer-implemented method for providing a set of process tool correctables, comprising:
 acquiring an overlay metrology result for each metrology target of a plurality of metrology targets distributed across one or more fields of a wafer of a lot of wafers;   
       acquiring a quality metric associated with each acquired overlay metrology result;
 determining a plurality of modified overlay values for the plurality of metrology targets utilizing the acquired overlay metrology result and the associated quality metric result for each metrology target, wherein the modified overlay function is a function of at least one material parameter factor; 
 generating a process tool correctable function and a set of residuals corresponding with the process tool correctable function for a plurality of material parameter factors; 
 determining a value of the material parameter factor suitable for at least substantially minimizing the set of residuals; and 
 determining a set of process correctables associated with the at least substantially minimized set of residuals. 
 
     
     
         2 . The method of  claim 1 , wherein the acquiring a quality metric associated with each acquired overlay metrology result, comprises:
 generating a quality metric for each acquired overlay metrology result utilizing a quality metric generation process.   
     
     
         3 . The method of  claim 1 , wherein the acquiring an overlay metrology result for each metrology target of a plurality of metrology targets distributed across one or more fields of a wafer of a lot of wafers, comprises:
 performing an overlay measurement on each metrology target of a plurality of metrology targets distributed across one or more fields of a wafer of a lot of wafers.   
     
     
         4 . The method of  claim 1 , further comprising:
 transmitting the set of process tool correctables associated with the at least substantially minimized set of residuals to one or more process tools.   
     
     
         5 . The method of  claim 1 , further comprising:
 performing a tool induced shift (TIS) correction process to at least some of the acquired plurality of overlay metrology measurement signals.   
     
     
         6 . The method of  claim 1 , wherein the modified overlay function is a linear function of at least one material parameter factor. 
     
     
         7 . The method of  claim 1 , wherein the modified overlay function is a function of at least one of a wavelength of illumination, a focus position, a direction of illumination, a polarization configuration, or a filter configuration. 
     
     
         8 . A computer-implemented method for identifying a variation in process tool correctables, comprising:
 acquiring an overlay metrology result for each metrology target of a plurality of metrology targets distributed across one or more fields of a wafer of a lot of wafers; acquiring a quality metric associated with each acquired overlay metrology result;
 determining a plurality of modified overlay values for the plurality of metrology targets utilizing the acquired overlay metrology result for each metrology target and a quality function, the quality function being a function of the acquired quality metric of each metrology target; 
 generating a plurality of sets of process tool correctables by determining a set of process tool correctables for each of a plurality of randomly selected samplings of the acquired overlay metrology results and the associated quality metrics of the plurality of metrology targets utilizing the plurality of modified overlay values, wherein each of the random samplings is of the same size; and 
 identifying a variation in the plurality of sets of process tool correctables. 
   
     
     
         9 . The method of  claim 8 , wherein the acquiring a quality metric associated with each acquired overlay metrology result, comprises:
 generating a quality metric for each acquired overlay metrology result utilizing a quality metric generation process.   
     
     
         10 . The method of  claim 8 , wherein the acquiring an overlay metrology result for each metrology target of a plurality of metrology targets distributed across one or more fields of a wafer of a lot of wafers, comprises:
 performing an overlay measurement on each metrology target of a plurality of metrology targets distributed across one or more fields of a wafer of a lot of wafers.   
     
     
         11 . A computer-implemented method for providing process signature mapping, comprising:
 forming a plurality of proxy targets on a reticle;   forming a plurality of device correlation targets on a wafer;   determining a first process signature as a function of position across the wafer by comparing a first set of metrology results acquired from the plurality of proxy targets following a lithography process and prior to a first etching process of the wafer and at least a second set of metrology results acquired from the plurality of proxy targets following the first etching process of the wafer;   correlating the first process signature with a specific process path;   measuring a device correlation bias following the first etching process by performing a first set of metrology measurements on the plurality of device correlation targets of the wafer, the device correlation bias being the bias between a metrology structure and a device of the wafer;   determining an additional etch signature for each additional process layer and for each additional non-lithographic process path of the wafer as a function of position across the wafer;   measuring an additional device correlation bias following each additional process layer and each additional non-lithographic process path of the wafer; and   generating a process signature map database utilizing the determined first etch signature and each of the additional etch signatures and the first measured device correlation bias and each additional device correlation bias.   
     
     
         12 . The method of  claim 11 , wherein the comparing a first set of metrology results acquired from the plurality of proxy targets following a lithography process and prior to a first etching process of the wafer and at least a second set of metrology results acquired from the plurality of proxy targets following the first etching process of the wafer comprises:
 determining a difference between a first set of metrology results acquired from the plurality of proxy targets following a lithography process and prior to a first etching process of the wafer and at least a second set of metrology results acquired from the plurality of proxy targets following the first etching process of the wafer.   
     
     
         13 . The method of  claim 11 , wherein the first set of metrology results from the plurality of proxy targets are acquired following a lithography process by performing a first set of metrology measurements on the plurality of proxy targets following a lithography process. 
     
     
         14 . The method of  claim 11 , wherein the at least a second set of metrology results from the plurality of proxy targets are acquired following the first etching process of the wafer by performing at least a second set of metrology measurements on the plurality of proxy targets following the first etching process of the wafer. 
     
     
         15 . The method of  claim 11 , wherein at least one of the first set of metrology results from the plurality of proxy targets or the at least a second set of metrology results from the plurality of proxy targets are acquired utilizing one or more overlay metrology processes. 
     
     
         16 . The method of  claim 11 , wherein the measuring a device correlation bias following the first etching process by performing a first set of metrology measurements on the plurality of device correlation targets of the wafer comprises:
 measuring a device correlation bias following the first etching process by performing a first set metrology measurements on the plurality of device correlation targets of the wafer, the first set of metrology measurements performed utilizing at least one of a CD-SEM based metrology system or an AFM-based metrology system.   
     
     
         17 . The method of  claim 11 , wherein the reticle is at least one of a test reticle or a product reticle. 
     
     
         18 . The method of  claim 11 , further comprising:
 operating an advance process control loop utilizing the generated process signature map database.   
     
     
         19 . The method of  claim 11 , further comprising:
 generating a set of process signature mapping correctables.