Application of Sub-resolution Assist Features in Photo Process

Application of Sub-resolution Assist Features in Photo Process. The pattern on the mask is projected on the photoresist through the exposure system. Due to the imperfection of the optical system and the diffraction effect, the pattern on the photoresist is not completely consistent with the pattern on the mask. Using optical proximity correction (OPC) can correct the pattern on the mask so that the pattern projected on the photoresist meets the design requirements as much as possible. At the 90nm node, the sub-resolution assist feature in the OPC method is introduced, which can solve the problem that the process window for some prohibiting periodic patterns is too small. But in other respects, there is little literature discussing the application of sub-resolution assist features. This paper reveals that in the photolithography process, adding sub-resolution assist features have other beneficial effects and functions for the photolithography process.