TIP-OPC: a new topological invariant paradigm for pixel based optical proximity correction

As the 193 nm lithography is likely to be used for 45 nm and even 32 nm processes, much more stringent requirement will be posed on optical proximity correction (OPC) technologies. Currently, there are two OPC approaches - the model-based OPC (MB-OPC) and the inverse lithography technology (ILT). MB-OPC generates masks which is less complex compared with ILT. But ILT produces much better results than MB-OPC in terms of contour fidelity because ILT is a pixel based method. Observing that MB-OPC preserves the mask shape topologies which leads to a lower mask complexity, we combine the strengths of both methods - the topology invariant property and the pixel based mask representation. To the best of our knowledge, it is the first time that this topological invariant pixel based OPC (TIP-OPC) paradigm is proposed, which fills the critical hole of the OPC landscape and potentially has many new applications. Our technical novelty includes the lithography friendly mask topological invariant operations, the efficient fast Fourier transform based cost function sensitivity computation and the TIP-OPC algorithm. The experimental results show that TIP-OPC can achieve much better post OPC contours compared with MB-OPC while maintaining the mask shape topologies.