Local registration (LREG) measurement for beam deflector monitoring

Position errors in reticles come from many sources; the writers play the most important influence on them. Several methods can be used for position error monitoring, such as registration / mask-to-mask overlay measurement for global position errors and writer deflector monitoring for local position errors. Getting smaller and smaller image placement and overlay of writers shown for advanced products, therefore, mask shops need advanced tools and methods to monitor conveniently and quickly. The Local Registration (LREG) function be created for this project, 1500 positions (in 15 x 15 μm² area) can be measured in less than 15 minutes by the function. Not only the health of the beam deflector but also the stitching condition of the writer could be obtained by the function. Moreover, the function would be extended for global registration and mask-to-mask overlay monitoring and compared to conventional (standard measurement) methods.