In an attempt to develop the dual damascene process in 0.13 micrometer design rule, the trench optics, resist usage, reflectivity control and BARC strategy for 0.18 micrometer S/L on 0.20 micrometer via dual damascene process are discussed. The difficulty of 0.18 micrometer trench process will be concentrated by two reasons: First, the trench optics is totally different from the traditional L/S patterns either observing the pupil plane wave vector or the aerial image versus defocus, it contains the intrinsic limitation to drive and enough process DOF. Secondly, the PR residues remain in via due to the weak light incidence into via as soon as trench exposure. The side issues are the MEEF problem in dark field exposure and lens aberration problem enhanced in the use of PSM or some kinds of special customized illumination filter CIFs. As a result, the negative resist together with NA equals 0.55, (sigma) equals 0.8, annular 1/2 illumination were applied, it reveals that all mentioned issues are properly compromised by this optimized condition. It is also found that the PR window and profile is quite sensitive to substrate acidity and reflectivity. When BARC protecting coating and reflectivity control problems are taken into account simultaneously, the thin conformal BARC and fully filled polymer on dual SiOXNY underlayer are introduced to get a good profile and CD control. Experimental results exhibit the feasibility in manufacturing.