An approach to building photomask CD SEM recipe for HOLON ZX using CATS

Mask metrology is a key signoff step in photomask manufacturing process. The challenges for mask makers today are issues revolving around reliably measuring CD (Critical Dimensions) of features on device patterns and mask registration, as the complexity of the patterns increase. These challenges continue to grow on due to the increasing complexity of mask design and the shrinking dimensions of critical features. The CDs are typically measured by scanning electron microscope (CD-SEM). Registration deals with the accurate placement of features on the mask, this paper has a primary focus on mask metrology. To support the mask metrology needs mentioned above, CATS® worked with HOLON to generate an offline CDSEM recipe in both GUI/non-GUI mode for automatic measurement. This implementation leads to the customer being able to automate the process of metrology to effectively use CATS® with the HOLON ZX tool. CATS® integration allows for exhaustive tool commands that can be preset in the CATS® setup file to generate CDSEM recipe. CATS® validates the recipe generation to optimize ZX productivity. To support this flow, here is the outline and the necessary building blocks: - CATS® reads the Mask data (VSB, MEBES, JEOL) job deck with the device patterns, along with metrology locations (Measurements point file) to place the desired marks. - The setup (Job deck and Marks) can be saved as a CATS® Internal job deck format for better efficiency. - The flow terminates with the WRITEFILE step, translating the CATS® Job deck to Machine format files that are needed for automatic measurement on the Holon Tool (CSV file, OASIS, Bitmap files as per specification).