Tamer Desouky
Mentor Graphics

As the process of migration of Optical process correction (OPC) recipes continues to go from sparse to dense computations, a run time effectiveness issue persists to remain for huge structures that exist in some metal and active layers designs. Even for 45 and 32 nm technology nodes, some polygons might be several microns in width consuming a vast amount of simulation time and order of magnitudes more than sparse simulations to converge. Practically, this problem is pronounced, which is usually the case, when the design comprises these huge structures and other small critical ones that needs many iterations and careful tuning to converge. And thus, a considerable amount of run time will be wasted while applying these sophisticated recipes on big structures that could originally converge within few iterations using a simple recipe. In this context, a convergence-based dense OPC recipe is proposed to deal with designs that have both types of structures. The basic idea is to check convergence prior starting next iteration and skip the rest of the iterations if the whole simulated frame has converged within a predefined tolerance. Also, a reasonable way to define tolerances is explored.