New Electron Beam Proximity effects Correction (EBPC) approach for 45nm and 32nm nodes

After the last successful results obtained these last years, EBDW (E-Beam Direct Write) use for ASIC manufacturing is now demonstrated. However, throughput and resolution capabilities need to be improved to push its interest for fast cycle product and advanced R&D applications. In this way, the development of the process needs a good dimensional control of patterns. That means a better control of the proximity effects affected by the back scattering electrons and others phenomenon. There exist several methods to provide a correction for these effects and the most commonly used is that of dose adjustment as implemented by PDF solutions PROXECCO software package. However it has been observed that this correction is not perfect and significantly it fails to accurately correct the smallest and most dense structures encountered in designs with features below 65nm. To continue reducing feature sizes a method to provide a complementary correction to PROXECCO has been proposed. Based upon detailed characterization of the observed effects a rules correction scheme has been developed not dissimilar to the rule based corrections used in optical proximity correction (OPC). This Electron Beam Proximity Correction, or EBPC, has been shown to provide good results down to 40nm, with improvements in CD linearity, the isolated dense bias (IDB), line end shortening (LES), mask error enhancement factor (MEEF) and the energy latitude (EL) all of which leads to an improvement in the overall accuracy of the design, and furthermore an improvement in the process window.