Optimizing Subresolution Assist Features Using Test Pattern Method

In the field of subwavelength lithography, the rulebased subresolution assist features insertion is an important technology. Regardless of optical proximity correction effect, the conventional method needs experience to better SRAF. A new optimizing SRAF method using test patterns is presented. Combined with conventional optical proximity correction flow, it can solve problems such as small process window and SRAF printout. Edge placement error (EPE) and process window are measured and tested on the standard benchmark circuits. The EPE has decreased 10%, while all EPEs under different process windows have also bettered.