DSA-aware assist features

DSA-aware optical or EUV lithography assist features (AFs) extend the capabilities of both traditional SRAFs and printable AFs (PrAFs). For instance, in a graphoepitaxy DSA process, where confinement wells are formed by DUV lithography, the process window of the DUVL process may be further improved by using PrAFs, as long as the confinement wells resulting from these PrAFs are sized and shaped so that they are “sealed” by the etch resistant outcomes of the DSA process. A method to optimize placement of such DSA-aware PrAFs is presented, along with a method utilizing a regular array of etch resistant confinement wells with localized modifications of their size or shape to form etch transferrable features. Both methods are tested and verified in simulations of DUV lithography and DSA.