Mask data rank and printability verification function of mask inspection system

With continued shrinkage of the semiconductor technology node, the inspection of mask with a single preset defect detection sensitivity level becomes impractical because of the increase occurrence of false capturing of defects. Inspection of leading-edge masks with conventional defect detection method, redundant detection of defects such as pseudo defects, or anomalies such as slightly deformed OPCs caused by assist features tend to increase the Turn Around Time (TAT) and cost of ownership (COO). This report describes a new method for the inspection of mask. It assigns defect detection sensitivity levels to local area inspections and is named as Regional Sensitivity Applied Inspection (RSAI). Then, the sensitivity information from each local area is converted into a format that can be fed into a Mask Data Rank (MDR) which is represented on the basis of pattern prioritization determined at the device design stage. Core technologies employing this concept resulted in the shortening of TAT where samples of actual device mask patterns were used. Printability verification functions (PVF) were applied to the advancement of technologies such as to Source Mask Optimization (SMO) technology. We report on the shortening of TAT that was achieved by the implementation of a new inspection technology that combines RSAI with MDR, and employs printability verification functions.