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 designing a stencil for particle beam writing and fabricating a device, the method comprising the steps of:
 storing a cell projection (CP) cell library information for a plurality of CP cells in the form of a data structure, the cell projection library information being generated by a stencil design system;   referencing the CP cell library data by a particle beam writing system; and   writing patterns on the device depending on the referenced CP cell library information.   
     
     
         2 . The method of  claim 1 , further comprising performing a proximity effect correction, the proximity effect correction being performed by modifying a plurality of CP cell patterns in the CP cell library. 
     
     
         3 . The method of  claim 2 , wherein performing the proximity effect correction comprises the steps of:
 attaching a plurality of identification information to each of the plurality of CP cell patterns, wherein each of the plurality of identification information comprises an information about a first pattern on the device layout, the pattern being adjacent to a second pattern on the layout, the second pattern corresponding to the CP cell pattern; and   carrying out proximity effect correction based on the attached identification information.   
     
     
         4 . The method of  claim 3 , wherein the identification information about the first pattern comprises the portions of the second pattern which are abutted or overlapped by the first pattern. 
     
     
         5 . The method of  claim 4 , further comprising the steps of:
 determining a rectangular region of the CP cell pattern, such that a corresponding rectangular region in the second pattern is not overlapped by the first pattern; and   recording the location of all parts of the CP cell pattern that extend outside of the rectangular region.   
     
     
         6 . The method of  claim 2 , wherein performing the proximity effect correction comprises the steps of:
 a. simulating a printed image of a pattern, the pattern being selected from the plurality of CP cell patterns;   b. comparing a target layout image with the simulated printed image;   c. modifying the CP cell pattern based on the comparison; and   d. iterating through steps a, b and c until the simulated printed image matches the target layout image within a predetermined tolerance.   
     
     
         7 . The method of  claim 1 , further comprising computing an improvement of the throughput of the particle beam writing system using the CP cell library information, compared to the throughput of the particle beam writing system when using a method other than the CP cell library information. 
     
     
         8 . The method of  claim 7 , wherein the throughput of the particle beam writing system using the CP cell library information is compared to the throughput of the particle beam writing system using VSB shots. 
     
     
         9 . The method of  claim 1 , further comprising providing to the stencil design system target parameters for the generated cell projection library information, the parameters being selected from a group comprising particle beam writing system throughput, pattern accuracy, pattern precision, and stencil mask configuration. 
     
     
         10 . The method of  claim 1 , further comprising the step of using a design library as input to the stencil design system, the design library comprising a plurality of cells. 
     
     
         11 . The method of  claim 10  wherein the stencil design system partitions a pattern of one design library cell, generating a plurality of CP cells from the pattern of the design library cell. 
     
     
         12 . The method of  claim 11  wherein the size of the design library cell exceeds a predetermined maximum for a single CP cell. 
     
     
         13 . The method of  claim 11  wherein the partitioning of the design library cell pattern comprises avoiding the cutting of shapes in the pattern in critical areas of the library cell, thereby reducing stitching alignment errors. 
     
     
         14 . The method of  claim 11  further comprising the step of placing the plurality of CP cells in mutually adjoining positions on the stencil, thereby improving throughput of the particle beam writing system compared to placing the plurality of CP cells distant from each other on the stencil. 
     
     
         15 . A system for designing a stencil for particle beam writing, to fabricate a device, the system comprising:
 a stencil pattern generation module, the stencil pattern generation module generating a stencil pattern database, the stencil pattern database comprising a plurality of geometric patterns of CP (Cell Projection) cells; and   a stencil pattern placement module, the stencil pattern placement module generating a stencil layout and a CP cell table.   
     
     
         16 . The system of  claim 15 , wherein the stencil pattern generation module comprises a proximity effect correction module, the proximity effect correction module performing proximity effect correction by modifying the plurality of geometric patterns of CP cells. 
     
     
         17 . The system of  claim 15  further comprising a computing improvement module, the computing improvement module computing an improvement of the throughput of the particle beam writing system using the generated stencil pattern database, in comparison with the throughput of the particle beam writing system when not using the generated stencil pattern database. 
     
     
         18 . The system of  claim 17  wherein the throughput of the particle beam writing system using the generated stencil pattern database is compared to the throughput of the particle beam writing system using VSB shots. 
     
     
         19 . The system of  claim 15 , wherein the particle beam writing comprises an electron beam writing. 
     
     
         20 . A computer program product for designing a stencil for particle beam writing, to fabricate a device, the computer program product comprising a computer readable medium comprising program instructions for:
 analyzing a design library to select CP (Cell Projection) cell candidates;   performing proximity effect correction for each of the CP cell candidates by modifying geometric pattern data for the CP cell candidate;   separating each CP cell candidate into a plurality of CP cells for large CP cell candidates; and   placing a plurality of corrected and separated CP cells on a stencil.   
     
     
         21 . The computer program product of  claim 20  further comprising computing a throughput improvement of the particle beam writing for the design library using the CP cells, compared to the throughput when the computer program product is not used.