The shrinkage of design rule and low-cost production need the extension of i-line lithographic equipments below 0.30micrometers patterning. The various resolution enhancement techniques (RETs) of i-line lithography have been implemented for low k1 process. In this paper, we optimized the optical and material parameters such as the resist thickness, mask type, off-axis illumination (OAI), and bottom anti-reflective coating for line/space patterns below 0.30micrometers design rule. We designed the experimental scheme on the basis of the statistical method and analyzed the result such as resolution, process margin, optical proximity effect, etc. The minimum resolution of 0.22 micrometers was achieved using the above RET methods where the k1 factor was 0.38. The OAI method plays a crucial role for the resolution enhancement. The thin resist process has an advantage for minimization of OPE factor. We also discus the correlation of the optimized parameters and suggest a combination of the RET method for the specific feature type.