Method and system for stencil design for particle beam writing

Abstract

Various embodiments of the present invention relate to particle beam writing to fabricate an integrated circuit on a wafer. In various embodiments, cell projection (CP) cell library information is stored in the form of a data structure. Subsequently, the CP cell library information is referenced by a writing system. The patterns are written on the wafer depending on the referenced CP cell library.

1 . A method for distortion correction of a cell projection (CP) cell pattern placed on a stencil, for use with a particle beam writing system, the method comprising the steps of:
 a) inputting a distortion model comprising i) forms or files for parameters, and ii) scripts for simulation and correction of stencil position-dependent distortion resulting from imperfections in the particle beam writing system;   b) inputting a stencil layout, wherein the stencil layout comprises the placed CP cell pattern;   c) simulating a printed image of the placed CP cell pattern using the distortion model;   d) comparing the printed image with a target layout image;   e) modifying the placed CP cell pattern if the printed image does not match the target layout image within a predetermined tolerance; and   f) iterating through steps c, d, and e until the printed image matches the target layout image within the predetermined tolerance.   
     
     
         2 . The method of  claim 1  wherein the step of modifying is automatic. 
     
     
         3 . The method of  claim 1  wherein the step of modifying is manual. 
     
     
         4 . The method of  claim 3  wherein a layout editor is used to perform the manual modification. 
     
     
         5 . The method of  claim 1  wherein the step of modifying is partially automatic and partially manual. 
     
     
         6 . A method for designing a stencil for particle beam writing, the method comprising the steps of:
 generating a placement on a stencil of a plurality of CP cell patterns; and   performing distortion correction by modifying the plurality of placed CP cell patterns, wherein the step of performing distortion correction is based on a deposition energy, and wherein the step of performing distortion correction comprises the steps of:
 determining a plurality of observation points for each of a plurality of simulated printed images of the placed CP cell patterns, each of the observation points being placed on the perimeter of a shape of one of the simulated printed images; 
 determining a plurality of target deposition energies at the observation points, the plurality of target deposition energies being a required deposition energy at each of the plurality of observation points; 
 computing a difference between a simulated deposited energy at each of the plurality of observation points and the corresponding target deposition energy; and 
 minimizing the difference between the simulated deposited energy at each of the plurality of observation points and the corresponding target deposition energy by moving edges of the placed CP cell pattern shapes, while keeping the observation points fixed. 
   
     
     
         7 . The method of  claim 6 , further comprising the step of performing a design rule check on the distortion-corrected placed CP cell patterns. 
     
     
         8 . The method of  claim 6 , further comprising the step of storing the placed CP cell patterns in a stencil layout database. 
     
     
         9 . The method of  claim 6 , further comprising the step of storing placement information for the placed CP cell patterns in a CP cell table. 
     
     
         10 . The method of  claim 6  wherein the particle beam writing comprises electron beam writing. 
     
     
         11 . A system for distortion correction of a cell projection (CP) cell pattern placed on a stencil for use with a particle beam writing system comprising:
 a distortion model comprising i) forms or files for parameters, and ii) scripts for simulation and correction of stencil position-dependent distortion resulting from imperfections in the particle beam writing system;   a device capable of inputting a stencil layout, wherein the stencil layout comprises the placed CP cell pattern;   a device capable of simulating a printed image of the placed CP cell pattern using the distortion model;   a device capable of comparing the simulated printed image with a target layout image; and   a device capable of modifying the placed CP cell pattern if the simulated printed image does not match the target layout image within a predetermined tolerance.   
     
     
         12 . The system of  claim 11  wherein the device capable of modifying the placed CP cell pattern comprises a layout editor. 
     
     
         13 . The system of  claim 11  wherein the device capable of modifying the placed CP cell pattern performs modification automatically. 
     
     
         14 . The system of  claim 11  wherein the particle beam writing comprises electron beam writing. 
     
     
         15 . A system for designing a stencil for particle beam writing, the system comprising:
 a stencil pattern placement module, the stencil pattern placement module generating a stencil layout and a CP cell table, the stencil pattern placement module comprising a distortion correction module,   wherein the distortion correction module performs distortion correction on a plurality of placed CP cell patterns, the distortion correction comprising the steps of:
 determining a plurality of observation points for each of a plurality of simulated printed images of the placed CP cell patterns, each of the observation points being placed on the perimeter of a shape of one of the simulated printed images; 
 determining a plurality of target deposition energies at the observation points, the plurality of target deposition energies being a required deposition energy at each of the plurality of observation points; 
 computing a difference between a simulated deposited energy at each of the plurality of observation points and the corresponding target deposition energy; and 
 minimizing the difference between the simulated deposited energy at each of the plurality of observation points and the corresponding target deposition energy by moving edges of the placed CP cell pattern shapes, while keeping the observation points fixed. 
   
     
     
         16 . The system of  claim 15  wherein the particle beam writing comprises electron beam writing.