Recently, as the design rule of the device is rapidly tightened, defect control is more critical and high-end masks like 256 M and 1 G DRAM level have difficulty for database inspection due to high data volume, data density, OPC, etc. Therefore, it is necessary to evaluate the machine capability of database inspection and defect capture ability for critical layer. For the experiment, we prepared three test plates that have tight CD design and extreme small OPC patterns, and one of them is combined by 4 different layers as metal, contact, ipso, and poly and design rule is 1.0 - 1.5 micrometer. And we shrinked the some area (80, 75%) for confirming the limitation of DB inspection. Through this evaluation, we tried to identify current barriers such as CD uniformity problem, and overcome the barriers and find ways how to improve the inspection capability.