A novel dual layer polymeric anti-reflective coating (PARC) process has been developed for sub-0.18micrometers KrF lithography. The refractive index, n, and the extinction coefficient, k, of PARC can be tuned to match the optical properties of various substrates. The PARC is a uniform and conformal layer of thin film, which significantly improves the CD uniformity of critical layers such as polysilicon get and other features over the severe topography. However, the high k PARC has scum issue near the edge of 0.18 micrometers polysilicon line. Some unknown active chemical reaction occurs when high k PARC is directly adhered to the photoresist. The process window is much improved after insertion of a layer of lower k PARC between photoresist and the polysilicon film. With the process simulation, the optimized dual layer of PARC are stacked with 300A of lower k and 300A of higher k. However the process window from the simulation is quite small, the reflectively of less than 2 percent has only +/- 30A for both k values of PARC. The forming rate of the PARC could be controlled to as low as 4.3A per second and with very good film uniformity of less than 5 percent. We then process the dual layer of PARC on 2500A polysilicon film with 27A gate oxide, a 0.8micrometers DOF of process window is obtained for 0.18micrometers polysilicon gate line. All the scum near the edge of polysilicon gate line is disappeared with the new dual layer PARC process.