The optical proximity effect can be a substantial fraction of the CD error budget. It is insufficient to determine the proximity effect as the difference between line-width in an equal line/gap pattern with that of an isolated line. Other geometries may have greater proximity induced line-width errors. We present here a comprehensive, four parameter, analytic process to characterize actual proximity. It is shown that when individual, geometry-dependent line bias is applied line-width uniformity can be reduced to the +/- 10 nm range. Using the +/- 10% CD criteria, individual line bias expands the range of exposure dose and depth of focus.
Richard C. Henderson,
Oberdan W. Otto,
"Correcting for proximity effect widens process latitude", Proc. SPIE 2197, Optical/Laser Microlithography VII, (17 May 1994); doi: 10.1117/12.175430; https://doi.org/10.1117/12.175430