System and Method for Lithography Exposure With Correction of Overlay Shift Induced By Mask Heating

Abstract

A method of exposing a wafer substrate includes receiving an integrated circuit (IC) design layout defining a pattern; determining a temperature profile of a mask based on the IC design layout, the pattern being formed on the mask; calculating a pre-corrected overlay shift for the mask based on the calculated temperature profile; and exposing a resist layer coated on a substrate using the mask with overlay compensation based on the pre-corrected overlay shift.

What is claimed is: 
     
         1 . A method comprising:
 prior to performing a process on a substrate, determining a temperature of a mask that is predicted to occur during the performing of the process of the substrate,   calculating an overlay shift for the mask based on the temperature of the mask that is predicted to occur during the performing of the process of the substrate; and   forming a patterned resist layer on the substrate using the mask with overlay compensation based on the calculated overlay shift.   
     
     
         2 . The method of  claim 1 , wherein determining the temperature of the mask that is predicted to occur during the performing of the process of the substrate includes determining a heating profile defined in a formula T=a1−b1*exp(−c1*x), wherein:
 T is mask temperature; 
 x is a number of exposed substrates in a lot; and 
 a1, b1 and c1 are coefficients determined by mask data and exposing data. 
 
     
     
         3 . The method of  claim 1 , wherein determining the temperature of the mask that is predicted to occur during the performing of the process of the substrate includes a cooling profile defined in a formula T=exp(−c2*(x−d2)), wherein
 T is mask temperature; 
 x is cooling time; and 
 c2 and d2 are coefficients determined by mask data and exposing data. 
 
     
     
         4 . The method of  claim 1 , wherein forming the patterned resist layer on the substrate using the mask with overlay compensation based on the calculated overlay shift includes:
 forming a resist layer on the substrate;   exposing the resist layer with deep ultraviolet radiation energy; and   developing the resist layer to form the patterned resist layer.   
     
     
         5 . The method of  claim 1 , wherein forming the patterned resist layer on the substrate using the mask with overlay compensation based on the calculated overlay shift includes:
 forming a resist layer on the substrate;   exposing the resist layer with extreme ultraviolet radiation energy; and   developing the resist layer to form the patterned resist layer.   
     
     
         6 . The method of  claim 1 , further comprising performing an overlay measurement of the patterned resist layer; and
 determining whether the overlay measurement of the patterned resist layer meets a threshold.   
     
     
         7 . The method of  claim 7 , further comprising exposing the patterned resist layer when it is determined that the patterned resist layer fails to meet the threshold; and
 etching the substrate with the patterned resist layer when it is determining that the patterned resist layer meets the threshold.   
     
     
         8 . A method comprising:
 determining a temperature profile of a mask, wherein the temperature profile is a predicted temperature of the mask predicted to occur during a process performed on a substrate, wherein determining the temperature profile of the mask includes determining a heating profile defined in a formula T=a1−b1*exp(−c1*x), wherein:   T is mask temperature;   x is a number of exposed substrates in a lot; and   a1, b1 and c1 are coefficients determined by mask data and exposing data;   calculating an overlay shift for the mask based on the temperature profile of the mask; and   forming a patterned resist layer on the substrate using the mask with overlay compensation based on the calculated overlay shift.   
     
     
         9 . The method of  claim 8 , wherein determining the temperature profile of the mask further includes a cooling profile defined in a formula T=exp(−c2*(x−d2)), wherein
 T is mask temperature; 
 x is cooling time; and 
 c2 and d2 are coefficients determined by mask data and exposing data. 
 
     
     
         10 . The method of  claim 8 , further comprising etching the substrate while using the patterned resist layer as a mask. 
     
     
         11 . The method of  claim 8 , wherein the mask is a phase shift mask. 
     
     
         12 . The method of  claim 8 , wherein the mask is a reflective mask 
     
     
         13 . The method of  claim 8 , wherein determining the temperature profile of the mask further includes determining a first temperature profile for a first region of the mask and determining a second temperature profile for a second region of the mask. 
     
     
         14 . The method of  claim 13 , wherein the first temperature profile is different than the second temperature profile. 
     
     
         15 . A system comprising:
 an exposure tool operable to expose a substrate using a mask; and   a smart overlay controller operable to calculate a predicted overlay using a temperature profile of the mask, wherein the temperature profile is a predicted temperature of the mask predicted to occur during a process performed on the substrate, wherein the temperature profile of the mask includes a heating profile defined in a formula T=a1−b1*exp(−c1*x), wherein:
 T is mask temperature; 
 x is a number of exposed substrates in a lot; and 
 a1, b1 and c1 are coefficients determined by mask data and exposing data. 
   
     
     
         16 . The system of  claim 15 , wherein the exposure tool includes a radiation source operable to emit deep ultraviolet radiation energy. 
     
     
         17 . The system of  claim 15 , wherein the exposure tool includes a radiation source operable to emit ultraviolet radiation energy. 
     
     
         18 . The system of  claim 15 , further comprising an overlay tool operable to measure an overlay error of a material layer disposed over the substrate. 
     
     
         19 . The system of  claim 15 , wherein the overlay tool is coupled to the smart overlay controller such that the overlay tool is operable to send the measured overlay error to the smart overlay controller. 
     
     
         20 . The system of  claim 15 , wherein the temperature profile of the mask further includes a cooling profile defined in a formula T=exp(−c2*(x−d2)), wherein
 T is mask temperature; 
 x is cooling time; and 
 c2 and d2 are coefficients determined by mask data and exposing data.