As the world's largest mask making operation, TSMC's mask service is the interface between designers and our world class fabs. Mask services are linked and synchronized between our manufacturing facilities through a computer integrated management (CIM) system. For advanced technology masks, TSMC routinely conducts optical proximity check (OPC) conversions of GDS data. Silicon process tools and process materials, as well as design-for-manufacturing (DFM) requirements, are covered by the OPC models to facilitate the largest production window. TSMC regularly conducts mask checks for electro-static discharge (ESD) damage, scratches, particle deposition, pellicle frames and aging to keep each mask in the best possible condition.