In this paper, we report highly effective Optical Proximity Correction (OPC) techniques to improve the process margin in the photo lithography process of metal layer, which can be applied to 0.14 micrometer DRAM technology node and beyond. The proposed test pattern reflects the optical limitation of each situation, the rules can be established by simply investigating the test patterns which solves the problems such as lack of contact overlap margin, line-end shortening, and size reduction in isolated and island patterns. This sophisticated rule is considering the vertical environment as well. Thanks to systematic sequence for rule extraction, we could minimize additional burdens such as error occurrence, rule set-up time, data volume, manufacturing time of mask. By applying this method, DOF margin of metal layer could be improved from 0.4 micrometer to beyond 0.6 micrometer, which provides sufficient process window for mass production of 0.14 micrometer DRAM technology. In addition, we also confirmed that the new OPC technology could be extended to the metal layer of 0.11 micrometer DRAM.