Reticle CD-SEM for 65-nm technology node and beyond

For next generation photomask lithography, improved resolution and precision are required to monitor lithography tools and photomask processes. The newly developed LWM9000 SEM Critical Dimension Scanning Electron Microscope (CD-SEM) for photomask applications will be presented. Its proprietary electron optics technology combined with an improved detection system leads to sub-nanometer CD measurement repeatability by almost completely eliminating the effect of charging and contamination. In an effort to minimize integration into production environments and to facilitate the ease of use the new CD-SEM utilizes a graphical user interface and data evaluation software based on Leica Microsystems' LMS IPRO / LMS IPRO2. Presented in this paper is data showing leading edge CD measurement repeatability performance on chrome on glass substrates (COG), different types of phase shift masks (PSM), and resist plates. The virtual lack of charging in conjunction with a laser controlled stage, dramatically reduces the need for local feature alignment prior to CD measurement in most cases. The lack of need for local pattern alignment leads to increased throughput and high reliability during the measurement process. The standard system can be configured for manual loading or SMIF handling.